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-rw-r--r--lib/std/private/bitops_utils.nim22
-rw-r--r--lib/std/private/digitsutils.nim116
-rw-r--r--lib/std/private/dragonbox.nim1325
-rw-r--r--lib/std/private/gitutils.nim54
-rw-r--r--lib/std/private/globs.nim30
-rw-r--r--lib/std/private/jsutils.nim23
-rw-r--r--lib/std/private/miscdollars.nim34
-rw-r--r--lib/std/private/ntpath.nim61
-rw-r--r--lib/std/private/osappdirs.nim176
-rw-r--r--lib/std/private/oscommon.nim186
-rw-r--r--lib/std/private/osdirs.nim570
-rw-r--r--lib/std/private/osfiles.nim416
-rw-r--r--lib/std/private/ospaths2.nim1030
-rw-r--r--lib/std/private/osseps.nim113
-rw-r--r--lib/std/private/ossymlinks.nim78
-rw-r--r--lib/std/private/schubfach.nim436
-rw-r--r--lib/std/private/since.nim10
-rw-r--r--lib/std/private/strimpl.nim37
-rw-r--r--lib/std/private/syslocks.nim234
-rw-r--r--lib/std/private/threadtypes.nim176
-rw-r--r--lib/std/private/underscored_calls.nim24
-rw-r--r--lib/std/private/vmutils.nim17
-rw-r--r--lib/std/private/win_getsysteminfo.nim15
-rw-r--r--lib/std/private/win_setenv.nim106
24 files changed, 5231 insertions, 58 deletions
diff --git a/lib/std/private/bitops_utils.nim b/lib/std/private/bitops_utils.nim
new file mode 100644
index 000000000..0b9484416
--- /dev/null
+++ b/lib/std/private/bitops_utils.nim
@@ -0,0 +1,22 @@
+template forwardImpl*(impl, arg) {.dirty.} =
+  when sizeof(x) <= 4:
+    when x is SomeSignedInt:
+      impl(cast[uint32](x.int32))
+    else:
+      impl(x.uint32)
+  else:
+    when x is SomeSignedInt:
+      impl(cast[uint64](x.int64))
+    else:
+      impl(x.uint64)
+
+# this could also be implemented via:
+# import std/typetraits
+# template castToUnsigned*(x: SomeInteger): auto = cast[toUnsigned(typeof(x))](x)
+
+template castToUnsigned*(x: int8): uint8 = cast[uint8](x)
+template castToUnsigned*(x: int16): uint16 = cast[uint16](x)
+template castToUnsigned*(x: int32): uint32 = cast[uint32](x)
+template castToUnsigned*(x: int64): uint64 = cast[uint64](x)
+template castToUnsigned*(x: int): uint = cast[uint](x)
+template castToUnsigned*[T: SomeUnsignedInt](x: T): T = x
diff --git a/lib/std/private/digitsutils.nim b/lib/std/private/digitsutils.nim
new file mode 100644
index 000000000..f2d0d25cb
--- /dev/null
+++ b/lib/std/private/digitsutils.nim
@@ -0,0 +1,116 @@
+const
+  trailingZeros100: array[100, int8] = [2'i8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0,
+    0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0,
+    0, 0, 0, 0, 0, 0]
+
+  digits100: array[200, char] = ['0', '0', '0', '1', '0', '2', '0', '3', '0', '4', '0', '5',
+    '0', '6', '0', '7', '0', '8', '0', '9', '1', '0', '1', '1', '1', '2', '1', '3', '1', '4',
+    '1', '5', '1', '6', '1', '7', '1', '8', '1', '9', '2', '0', '2', '1', '2', '2', '2', '3',
+    '2', '4', '2', '5', '2', '6', '2', '7', '2', '8', '2', '9', '3', '0', '3', '1', '3', '2',
+    '3', '3', '3', '4', '3', '5', '3', '6', '3', '7', '3', '8', '3', '9', '4', '0', '4', '1',
+    '4', '2', '4', '3', '4', '4', '4', '5', '4', '6', '4', '7', '4', '8', '4', '9', '5', '0',
+    '5', '1', '5', '2', '5', '3', '5', '4', '5', '5', '5', '6', '5', '7', '5', '8', '5', '9',
+    '6', '0', '6', '1', '6', '2', '6', '3', '6', '4', '6', '5', '6', '6', '6', '7', '6', '8',
+    '6', '9', '7', '0', '7', '1', '7', '2', '7', '3', '7', '4', '7', '5', '7', '6', '7', '7',
+    '7', '8', '7', '9', '8', '0', '8', '1', '8', '2', '8', '3', '8', '4', '8', '5', '8', '6',
+    '8', '7', '8', '8', '8', '9', '9', '0', '9', '1', '9', '2', '9', '3', '9', '4', '9', '5',
+    '9', '6', '9', '7', '9', '8', '9', '9']
+
+# Inspired by https://engineering.fb.com/2013/03/15/developer-tools/three-optimization-tips-for-c
+# Generates:
+#   ```nim
+#   var res = ""
+#   for i in 0 .. 99:
+#     if i < 10:
+#       res.add "0" & $i
+#     else:
+#       res.add $i
+#   doAssert res == digits100
+#   ```
+
+proc utoa2Digits*(buf: var openArray[char]; pos: int; digits: uint32) {.inline.} =
+  buf[pos] = digits100[2 * digits]
+  buf[pos+1] = digits100[2 * digits + 1]
+  #copyMem(buf, unsafeAddr(digits100[2 * digits]), 2 * sizeof((char)))
+
+proc trailingZeros2Digits*(digits: uint32): int {.inline.} =
+  trailingZeros100[digits]
+
+when defined(js):
+  proc numToString(a: SomeInteger): cstring {.importjs: "((#) + \"\")".}
+
+func addChars[T](result: var string, x: T, start: int, n: int) {.inline.} =
+  let old = result.len
+  result.setLen old + n
+  template impl =
+    for i in 0..<n: result[old + i] = x[start + i]
+  when nimvm: impl
+  else:
+    when defined(js) or defined(nimscript): impl
+    else:
+      {.noSideEffect.}:
+        copyMem result[old].addr, x[start].unsafeAddr, n
+
+func addChars[T](result: var string, x: T) {.inline.} =
+  addChars(result, x, 0, x.len)
+
+func addIntImpl(result: var string, x: uint64) {.inline.} =
+  var tmp {.noinit.}: array[24, char]
+  var num = x
+  var next = tmp.len - 1
+  const nbatch = 100
+
+  while num >= nbatch:
+    let originNum = num
+    num = num div nbatch
+    let index = int16((originNum - num * nbatch) shl 1)
+    tmp[next] = digits100[index + 1]
+    tmp[next - 1] = digits100[index]
+    dec(next, 2)
+
+  # process last 1-2 digits
+  if num < 10:
+    tmp[next] = chr(ord('0') + num.uint8)
+  else:
+    let index = num * 2
+    tmp[next] = digits100[index + 1]
+    tmp[next - 1] = digits100[index]
+    dec next
+  addChars(result, tmp, next, tmp.len - next)
+
+when not defined(nimHasEnforceNoRaises):
+  {.pragma: enforceNoRaises.}
+
+func addInt*(result: var string, x: uint64) {.enforceNoRaises.} =
+  when nimvm: addIntImpl(result, x)
+  else:
+    when not defined(js): addIntImpl(result, x)
+    else:
+      addChars(result, numToString(x))
+
+proc addInt*(result: var string; x: int64) {.enforceNoRaises.} =
+  ## Converts integer to its string representation and appends it to `result`.
+  runnableExamples:
+    var s = "foo"
+    s.addInt(45)
+    assert s == "foo45"
+  template impl =
+    var num: uint64
+    if x < 0:
+      if x == low(int64):
+        num = cast[uint64](x)
+      else:
+        num = uint64(-x)
+      result.add '-'
+    else:
+      num = uint64(x)
+    addInt(result, num)
+  when nimvm: impl()
+  else:
+    when defined(js):
+      addChars(result, numToString(x))
+    else: impl()
+
+proc addInt*(result: var string; x: int) {.inline, enforceNoRaises.} =
+  addInt(result, int64(x))
diff --git a/lib/std/private/dragonbox.nim b/lib/std/private/dragonbox.nim
new file mode 100644
index 000000000..85ffea84a
--- /dev/null
+++ b/lib/std/private/dragonbox.nim
@@ -0,0 +1,1325 @@
+##  Copyright 2020 Junekey Jeon
+##  Copyright 2020 Alexander Bolz
+##
+##  Distributed under the Boost Software License, Version 1.0.
+##   (See accompanying file LICENSE_1_0.txt or copy at https://www.boost.org/LICENSE_1_0.txt)
+
+##  char* output_end = Dtoa(buffer, value);
+##
+##  Converts the given double-precision number into decimal form and stores the result in the given
+##  buffer.
+##
+##  The buffer must be large enough, i.e. >= DtoaMinBufferLength.
+##  The output format is similar to printf("%g").
+##  The output is _not_ null-terminted.
+##
+##  The output is optimal, i.e. the output string
+##   1. rounds back to the input number when read in (using round-to-nearest-even)
+##   2. is as short as possible,
+##   3. is as close to the input number as possible.
+##
+##  Note:
+##  This function may temporarily write up to DtoaMinBufferLength characters into the buffer.
+
+
+import std/private/digitsutils
+
+when defined(nimPreviewSlimSystem):
+  import std/assertions
+
+const
+  dtoaMinBufferLength*: cint = 64
+
+##  This file contains an implementation of Junekey Jeon's Dragonbox algorithm.
+##
+##  It is a simplified version of the reference implementation found here:
+##  https://github.com/jk-jeon/dragonbox
+##
+##  The reference implementation also works with single-precision floating-point numbers and
+##  has options to configure the rounding mode.
+
+template dragonbox_Assert*(x: untyped): untyped =
+  assert(x)
+
+# ==================================================================================================
+#
+# ==================================================================================================
+
+type
+  ValueType* = float
+  BitsType* = uint64
+
+type
+  Double* = object
+    bits*: BitsType
+
+const                         ##  = p   (includes the hidden bit)
+  significandSize*: int32 = 53
+
+const ##   static constexpr int32_t   MaxExponent     = 1024 - 1 - (SignificandSize - 1);
+     ##   static constexpr int32_t   MinExponent     = std::numeric_limits<value_type>::min_exponent - 1 - (SignificandSize - 1);
+  exponentBias*: int32 = 1024 - 1 + (significandSize - 1)
+
+const
+  maxIeeeExponent*: BitsType = BitsType(2 * 1024 - 1)
+
+const                         ##  = 2^(p-1)
+  hiddenBit*: BitsType = BitsType(1) shl (significandSize - 1)
+
+const                         ##  = 2^(p-1) - 1
+  significandMask*: BitsType = hiddenBit - 1
+
+const
+  exponentMask*: BitsType = maxIeeeExponent shl (significandSize - 1)
+
+const
+  signMask*: BitsType = not (not BitsType(0) shr 1)
+
+proc constructDouble*(bits: BitsType): Double  =
+  result.bits = bits
+
+proc constructDouble*(value: ValueType): Double  =
+  result.bits = cast[typeof(result.bits)](value)
+
+proc physicalSignificand*(this: Double): BitsType {.noSideEffect.} =
+  return this.bits and significandMask
+
+proc physicalExponent*(this: Double): BitsType {.noSideEffect.} =
+  return (this.bits and exponentMask) shr (significandSize - 1)
+
+proc isFinite*(this: Double): bool {.noSideEffect.} =
+  return (this.bits and exponentMask) != exponentMask
+
+proc isInf*(this: Double): bool {.noSideEffect.} =
+  return (this.bits and exponentMask) == exponentMask and
+      (this.bits and significandMask) == 0
+
+proc isNaN*(this: Double): bool {.noSideEffect.} =
+  return (this.bits and exponentMask) == exponentMask and
+      (this.bits and significandMask) != 0
+
+proc isZero*(this: Double): bool {.noSideEffect.} =
+  return (this.bits and not signMask) == 0
+
+proc signBit*(this: Double): int {.noSideEffect.} =
+  return ord((this.bits and signMask) != 0)
+
+
+# ==================================================================================================
+#
+# ==================================================================================================
+##  namespace
+##  Returns floor(x / 2^n).
+##
+##  Technically, right-shift of negative integers is implementation defined...
+##  Should easily be optimized into SAR (or equivalent) instruction.
+
+proc floorDivPow2*(x: int32; n: int32): int32 {.inline.} =
+  return x shr n
+
+proc floorLog2Pow10*(e: int32): int32 {.inline.} =
+  dragonbox_Assert(e >= -1233)
+  dragonbox_Assert(e <= 1233)
+  return floorDivPow2(e * 1741647, 19)
+
+proc floorLog10Pow2*(e: int32): int32 {.inline.} =
+  dragonbox_Assert(e >= -1500)
+  dragonbox_Assert(e <= 1500)
+  return floorDivPow2(e * 1262611, 22)
+
+proc floorLog10ThreeQuartersPow2*(e: int32): int32 {.inline.} =
+  dragonbox_Assert(e >= -1500)
+  dragonbox_Assert(e <= 1500)
+  return floorDivPow2(e * 1262611 - 524031, 22)
+
+# ==================================================================================================
+#
+# ==================================================================================================
+
+type
+  uint64x2* {.bycopy.} = object
+    hi*: uint64
+    lo*: uint64
+
+
+proc computePow10*(k: int32): uint64x2 {.inline.} =
+  const
+    kMin: int32 = -292
+  const
+    kMax: int32 = 326
+  const
+    pow10: array[kMax - kMin + 1, uint64x2] = [
+      uint64x2(hi: 0xFF77B1FCBEBCDC4F'u, lo: 0x25E8E89C13BB0F7B'u),
+      uint64x2(hi: 0x9FAACF3DF73609B1'u, lo: 0x77B191618C54E9AD'u),
+      uint64x2(hi: 0xC795830D75038C1D'u, lo: 0xD59DF5B9EF6A2418'u),
+      uint64x2(hi: 0xF97AE3D0D2446F25'u, lo: 0x4B0573286B44AD1E'u),
+      uint64x2(hi: 0x9BECCE62836AC577'u, lo: 0x4EE367F9430AEC33'u),
+      uint64x2(hi: 0xC2E801FB244576D5'u, lo: 0x229C41F793CDA740'u),
+      uint64x2(hi: 0xF3A20279ED56D48A'u, lo: 0x6B43527578C11110'u),
+      uint64x2(hi: 0x9845418C345644D6'u, lo: 0x830A13896B78AAAA'u),
+      uint64x2(hi: 0xBE5691EF416BD60C'u, lo: 0x23CC986BC656D554'u),
+      uint64x2(hi: 0xEDEC366B11C6CB8F'u, lo: 0x2CBFBE86B7EC8AA9'u),
+      uint64x2(hi: 0x94B3A202EB1C3F39'u, lo: 0x7BF7D71432F3D6AA'u),
+      uint64x2(hi: 0xB9E08A83A5E34F07'u, lo: 0xDAF5CCD93FB0CC54'u),
+      uint64x2(hi: 0xE858AD248F5C22C9'u, lo: 0xD1B3400F8F9CFF69'u),
+      uint64x2(hi: 0x91376C36D99995BE'u, lo: 0x23100809B9C21FA2'u),
+      uint64x2(hi: 0xB58547448FFFFB2D'u, lo: 0xABD40A0C2832A78B'u),
+      uint64x2(hi: 0xE2E69915B3FFF9F9'u, lo: 0x16C90C8F323F516D'u),
+      uint64x2(hi: 0x8DD01FAD907FFC3B'u, lo: 0xAE3DA7D97F6792E4'u),
+      uint64x2(hi: 0xB1442798F49FFB4A'u, lo: 0x99CD11CFDF41779D'u),
+      uint64x2(hi: 0xDD95317F31C7FA1D'u, lo: 0x40405643D711D584'u),
+      uint64x2(hi: 0x8A7D3EEF7F1CFC52'u, lo: 0x482835EA666B2573'u),
+      uint64x2(hi: 0xAD1C8EAB5EE43B66'u, lo: 0xDA3243650005EED0'u),
+      uint64x2(hi: 0xD863B256369D4A40'u, lo: 0x90BED43E40076A83'u),
+      uint64x2(hi: 0x873E4F75E2224E68'u, lo: 0x5A7744A6E804A292'u),
+      uint64x2(hi: 0xA90DE3535AAAE202'u, lo: 0x711515D0A205CB37'u),
+      uint64x2(hi: 0xD3515C2831559A83'u, lo: 0x0D5A5B44CA873E04'u),
+      uint64x2(hi: 0x8412D9991ED58091'u, lo: 0xE858790AFE9486C3'u),
+      uint64x2(hi: 0xA5178FFF668AE0B6'u, lo: 0x626E974DBE39A873'u),
+      uint64x2(hi: 0xCE5D73FF402D98E3'u, lo: 0xFB0A3D212DC81290'u),
+      uint64x2(hi: 0x80FA687F881C7F8E'u, lo: 0x7CE66634BC9D0B9A'u),
+      uint64x2(hi: 0xA139029F6A239F72'u, lo: 0x1C1FFFC1EBC44E81'u),
+      uint64x2(hi: 0xC987434744AC874E'u, lo: 0xA327FFB266B56221'u),
+      uint64x2(hi: 0xFBE9141915D7A922'u, lo: 0x4BF1FF9F0062BAA9'u),
+      uint64x2(hi: 0x9D71AC8FADA6C9B5'u, lo: 0x6F773FC3603DB4AA'u),
+      uint64x2(hi: 0xC4CE17B399107C22'u, lo: 0xCB550FB4384D21D4'u),
+      uint64x2(hi: 0xF6019DA07F549B2B'u, lo: 0x7E2A53A146606A49'u),
+      uint64x2(hi: 0x99C102844F94E0FB'u, lo: 0x2EDA7444CBFC426E'u),
+      uint64x2(hi: 0xC0314325637A1939'u, lo: 0xFA911155FEFB5309'u),
+      uint64x2(hi: 0xF03D93EEBC589F88'u, lo: 0x793555AB7EBA27CB'u),
+      uint64x2(hi: 0x96267C7535B763B5'u, lo: 0x4BC1558B2F3458DF'u),
+      uint64x2(hi: 0xBBB01B9283253CA2'u, lo: 0x9EB1AAEDFB016F17'u),
+      uint64x2(hi: 0xEA9C227723EE8BCB'u, lo: 0x465E15A979C1CADD'u),
+      uint64x2(hi: 0x92A1958A7675175F'u, lo: 0x0BFACD89EC191ECA'u),
+      uint64x2(hi: 0xB749FAED14125D36'u, lo: 0xCEF980EC671F667C'u),
+      uint64x2(hi: 0xE51C79A85916F484'u, lo: 0x82B7E12780E7401B'u),
+      uint64x2(hi: 0x8F31CC0937AE58D2'u, lo: 0xD1B2ECB8B0908811'u),
+      uint64x2(hi: 0xB2FE3F0B8599EF07'u, lo: 0x861FA7E6DCB4AA16'u),
+      uint64x2(hi: 0xDFBDCECE67006AC9'u, lo: 0x67A791E093E1D49B'u),
+      uint64x2(hi: 0x8BD6A141006042BD'u, lo: 0xE0C8BB2C5C6D24E1'u),
+      uint64x2(hi: 0xAECC49914078536D'u, lo: 0x58FAE9F773886E19'u),
+      uint64x2(hi: 0xDA7F5BF590966848'u, lo: 0xAF39A475506A899F'u),
+      uint64x2(hi: 0x888F99797A5E012D'u, lo: 0x6D8406C952429604'u),
+      uint64x2(hi: 0xAAB37FD7D8F58178'u, lo: 0xC8E5087BA6D33B84'u),
+      uint64x2(hi: 0xD5605FCDCF32E1D6'u, lo: 0xFB1E4A9A90880A65'u),
+      uint64x2(hi: 0x855C3BE0A17FCD26'u, lo: 0x5CF2EEA09A550680'u),
+      uint64x2(hi: 0xA6B34AD8C9DFC06F'u, lo: 0xF42FAA48C0EA481F'u),
+      uint64x2(hi: 0xD0601D8EFC57B08B'u, lo: 0xF13B94DAF124DA27'u),
+      uint64x2(hi: 0x823C12795DB6CE57'u, lo: 0x76C53D08D6B70859'u),
+      uint64x2(hi: 0xA2CB1717B52481ED'u, lo: 0x54768C4B0C64CA6F'u),
+      uint64x2(hi: 0xCB7DDCDDA26DA268'u, lo: 0xA9942F5DCF7DFD0A'u),
+      uint64x2(hi: 0xFE5D54150B090B02'u, lo: 0xD3F93B35435D7C4D'u),
+      uint64x2(hi: 0x9EFA548D26E5A6E1'u, lo: 0xC47BC5014A1A6DB0'u),
+      uint64x2(hi: 0xC6B8E9B0709F109A'u, lo: 0x359AB6419CA1091C'u),
+      uint64x2(hi: 0xF867241C8CC6D4C0'u, lo: 0xC30163D203C94B63'u),
+      uint64x2(hi: 0x9B407691D7FC44F8'u, lo: 0x79E0DE63425DCF1E'u),
+      uint64x2(hi: 0xC21094364DFB5636'u, lo: 0x985915FC12F542E5'u),
+      uint64x2(hi: 0xF294B943E17A2BC4'u, lo: 0x3E6F5B7B17B2939E'u),
+      uint64x2(hi: 0x979CF3CA6CEC5B5A'u, lo: 0xA705992CEECF9C43'u),
+      uint64x2(hi: 0xBD8430BD08277231'u, lo: 0x50C6FF782A838354'u),
+      uint64x2(hi: 0xECE53CEC4A314EBD'u, lo: 0xA4F8BF5635246429'u),
+      uint64x2(hi: 0x940F4613AE5ED136'u, lo: 0x871B7795E136BE9A'u),
+      uint64x2(hi: 0xB913179899F68584'u, lo: 0x28E2557B59846E40'u),
+      uint64x2(hi: 0xE757DD7EC07426E5'u, lo: 0x331AEADA2FE589D0'u),
+      uint64x2(hi: 0x9096EA6F3848984F'u, lo: 0x3FF0D2C85DEF7622'u),
+      uint64x2(hi: 0xB4BCA50B065ABE63'u, lo: 0x0FED077A756B53AA'u),
+      uint64x2(hi: 0xE1EBCE4DC7F16DFB'u, lo: 0xD3E8495912C62895'u),
+      uint64x2(hi: 0x8D3360F09CF6E4BD'u, lo: 0x64712DD7ABBBD95D'u),
+      uint64x2(hi: 0xB080392CC4349DEC'u, lo: 0xBD8D794D96AACFB4'u),
+      uint64x2(hi: 0xDCA04777F541C567'u, lo: 0xECF0D7A0FC5583A1'u),
+      uint64x2(hi: 0x89E42CAAF9491B60'u, lo: 0xF41686C49DB57245'u),
+      uint64x2(hi: 0xAC5D37D5B79B6239'u, lo: 0x311C2875C522CED6'u),
+      uint64x2(hi: 0xD77485CB25823AC7'u, lo: 0x7D633293366B828C'u),
+      uint64x2(hi: 0x86A8D39EF77164BC'u, lo: 0xAE5DFF9C02033198'u),
+      uint64x2(hi: 0xA8530886B54DBDEB'u, lo: 0xD9F57F830283FDFD'u),
+      uint64x2(hi: 0xD267CAA862A12D66'u, lo: 0xD072DF63C324FD7C'u),
+      uint64x2(hi: 0x8380DEA93DA4BC60'u, lo: 0x4247CB9E59F71E6E'u),
+      uint64x2(hi: 0xA46116538D0DEB78'u, lo: 0x52D9BE85F074E609'u),
+      uint64x2(hi: 0xCD795BE870516656'u, lo: 0x67902E276C921F8C'u),
+      uint64x2(hi: 0x806BD9714632DFF6'u, lo: 0x00BA1CD8A3DB53B7'u),
+      uint64x2(hi: 0xA086CFCD97BF97F3'u, lo: 0x80E8A40ECCD228A5'u),
+      uint64x2(hi: 0xC8A883C0FDAF7DF0'u, lo: 0x6122CD128006B2CE'u),
+      uint64x2(hi: 0xFAD2A4B13D1B5D6C'u, lo: 0x796B805720085F82'u),
+      uint64x2(hi: 0x9CC3A6EEC6311A63'u, lo: 0xCBE3303674053BB1'u),
+      uint64x2(hi: 0xC3F490AA77BD60FC'u, lo: 0xBEDBFC4411068A9D'u),
+      uint64x2(hi: 0xF4F1B4D515ACB93B'u, lo: 0xEE92FB5515482D45'u),
+      uint64x2(hi: 0x991711052D8BF3C5'u, lo: 0x751BDD152D4D1C4B'u),
+      uint64x2(hi: 0xBF5CD54678EEF0B6'u, lo: 0xD262D45A78A0635E'u),
+      uint64x2(hi: 0xEF340A98172AACE4'u, lo: 0x86FB897116C87C35'u),
+      uint64x2(hi: 0x9580869F0E7AAC0E'u, lo: 0xD45D35E6AE3D4DA1'u),
+      uint64x2(hi: 0xBAE0A846D2195712'u, lo: 0x8974836059CCA10A'u),
+      uint64x2(hi: 0xE998D258869FACD7'u, lo: 0x2BD1A438703FC94C'u),
+      uint64x2(hi: 0x91FF83775423CC06'u, lo: 0x7B6306A34627DDD0'u),
+      uint64x2(hi: 0xB67F6455292CBF08'u, lo: 0x1A3BC84C17B1D543'u),
+      uint64x2(hi: 0xE41F3D6A7377EECA'u, lo: 0x20CABA5F1D9E4A94'u),
+      uint64x2(hi: 0x8E938662882AF53E'u, lo: 0x547EB47B7282EE9D'u),
+      uint64x2(hi: 0xB23867FB2A35B28D'u, lo: 0xE99E619A4F23AA44'u),
+      uint64x2(hi: 0xDEC681F9F4C31F31'u, lo: 0x6405FA00E2EC94D5'u),
+      uint64x2(hi: 0x8B3C113C38F9F37E'u, lo: 0xDE83BC408DD3DD05'u),
+      uint64x2(hi: 0xAE0B158B4738705E'u, lo: 0x9624AB50B148D446'u),
+      uint64x2(hi: 0xD98DDAEE19068C76'u, lo: 0x3BADD624DD9B0958'u),
+      uint64x2(hi: 0x87F8A8D4CFA417C9'u, lo: 0xE54CA5D70A80E5D7'u),
+      uint64x2(hi: 0xA9F6D30A038D1DBC'u, lo: 0x5E9FCF4CCD211F4D'u),
+      uint64x2(hi: 0xD47487CC8470652B'u, lo: 0x7647C32000696720'u),
+      uint64x2(hi: 0x84C8D4DFD2C63F3B'u, lo: 0x29ECD9F40041E074'u),
+      uint64x2(hi: 0xA5FB0A17C777CF09'u, lo: 0xF468107100525891'u),
+      uint64x2(hi: 0xCF79CC9DB955C2CC'u, lo: 0x7182148D4066EEB5'u),
+      uint64x2(hi: 0x81AC1FE293D599BF'u, lo: 0xC6F14CD848405531'u),
+      uint64x2(hi: 0xA21727DB38CB002F'u, lo: 0xB8ADA00E5A506A7D'u),
+      uint64x2(hi: 0xCA9CF1D206FDC03B'u, lo: 0xA6D90811F0E4851D'u),
+      uint64x2(hi: 0xFD442E4688BD304A'u, lo: 0x908F4A166D1DA664'u),
+      uint64x2(hi: 0x9E4A9CEC15763E2E'u, lo: 0x9A598E4E043287FF'u),
+      uint64x2(hi: 0xC5DD44271AD3CDBA'u, lo: 0x40EFF1E1853F29FE'u),
+      uint64x2(hi: 0xF7549530E188C128'u, lo: 0xD12BEE59E68EF47D'u),
+      uint64x2(hi: 0x9A94DD3E8CF578B9'u, lo: 0x82BB74F8301958CF'u),
+      uint64x2(hi: 0xC13A148E3032D6E7'u, lo: 0xE36A52363C1FAF02'u),
+      uint64x2(hi: 0xF18899B1BC3F8CA1'u, lo: 0xDC44E6C3CB279AC2'u),
+      uint64x2(hi: 0x96F5600F15A7B7E5'u, lo: 0x29AB103A5EF8C0BA'u),
+      uint64x2(hi: 0xBCB2B812DB11A5DE'u, lo: 0x7415D448F6B6F0E8'u),
+      uint64x2(hi: 0xEBDF661791D60F56'u, lo: 0x111B495B3464AD22'u),
+      uint64x2(hi: 0x936B9FCEBB25C995'u, lo: 0xCAB10DD900BEEC35'u),
+      uint64x2(hi: 0xB84687C269EF3BFB'u, lo: 0x3D5D514F40EEA743'u),
+      uint64x2(hi: 0xE65829B3046B0AFA'u, lo: 0x0CB4A5A3112A5113'u),
+      uint64x2(hi: 0x8FF71A0FE2C2E6DC'u, lo: 0x47F0E785EABA72AC'u),
+      uint64x2(hi: 0xB3F4E093DB73A093'u, lo: 0x59ED216765690F57'u),
+      uint64x2(hi: 0xE0F218B8D25088B8'u, lo: 0x306869C13EC3532D'u),
+      uint64x2(hi: 0x8C974F7383725573'u, lo: 0x1E414218C73A13FC'u),
+      uint64x2(hi: 0xAFBD2350644EEACF'u, lo: 0xE5D1929EF90898FB'u),
+      uint64x2(hi: 0xDBAC6C247D62A583'u, lo: 0xDF45F746B74ABF3A'u),
+      uint64x2(hi: 0x894BC396CE5DA772'u, lo: 0x6B8BBA8C328EB784'u),
+      uint64x2(hi: 0xAB9EB47C81F5114F'u, lo: 0x066EA92F3F326565'u),
+      uint64x2(hi: 0xD686619BA27255A2'u, lo: 0xC80A537B0EFEFEBE'u),
+      uint64x2(hi: 0x8613FD0145877585'u, lo: 0xBD06742CE95F5F37'u),
+      uint64x2(hi: 0xA798FC4196E952E7'u, lo: 0x2C48113823B73705'u),
+      uint64x2(hi: 0xD17F3B51FCA3A7A0'u, lo: 0xF75A15862CA504C6'u),
+      uint64x2(hi: 0x82EF85133DE648C4'u, lo: 0x9A984D73DBE722FC'u),
+      uint64x2(hi: 0xA3AB66580D5FDAF5'u, lo: 0xC13E60D0D2E0EBBB'u),
+      uint64x2(hi: 0xCC963FEE10B7D1B3'u, lo: 0x318DF905079926A9'u),
+      uint64x2(hi: 0xFFBBCFE994E5C61F'u, lo: 0xFDF17746497F7053'u),
+      uint64x2(hi: 0x9FD561F1FD0F9BD3'u, lo: 0xFEB6EA8BEDEFA634'u),
+      uint64x2(hi: 0xC7CABA6E7C5382C8'u, lo: 0xFE64A52EE96B8FC1'u),
+      uint64x2(hi: 0xF9BD690A1B68637B'u, lo: 0x3DFDCE7AA3C673B1'u),
+      uint64x2(hi: 0x9C1661A651213E2D'u, lo: 0x06BEA10CA65C084F'u),
+      uint64x2(hi: 0xC31BFA0FE5698DB8'u, lo: 0x486E494FCFF30A63'u),
+      uint64x2(hi: 0xF3E2F893DEC3F126'u, lo: 0x5A89DBA3C3EFCCFB'u),
+      uint64x2(hi: 0x986DDB5C6B3A76B7'u, lo: 0xF89629465A75E01D'u),
+      uint64x2(hi: 0xBE89523386091465'u, lo: 0xF6BBB397F1135824'u),
+      uint64x2(hi: 0xEE2BA6C0678B597F'u, lo: 0x746AA07DED582E2D'u),
+      uint64x2(hi: 0x94DB483840B717EF'u, lo: 0xA8C2A44EB4571CDD'u),
+      uint64x2(hi: 0xBA121A4650E4DDEB'u, lo: 0x92F34D62616CE414'u),
+      uint64x2(hi: 0xE896A0D7E51E1566'u, lo: 0x77B020BAF9C81D18'u),
+      uint64x2(hi: 0x915E2486EF32CD60'u, lo: 0x0ACE1474DC1D122F'u),
+      uint64x2(hi: 0xB5B5ADA8AAFF80B8'u, lo: 0x0D819992132456BB'u),
+      uint64x2(hi: 0xE3231912D5BF60E6'u, lo: 0x10E1FFF697ED6C6A'u),
+      uint64x2(hi: 0x8DF5EFABC5979C8F'u, lo: 0xCA8D3FFA1EF463C2'u),
+      uint64x2(hi: 0xB1736B96B6FD83B3'u, lo: 0xBD308FF8A6B17CB3'u),
+      uint64x2(hi: 0xDDD0467C64BCE4A0'u, lo: 0xAC7CB3F6D05DDBDF'u),
+      uint64x2(hi: 0x8AA22C0DBEF60EE4'u, lo: 0x6BCDF07A423AA96C'u),
+      uint64x2(hi: 0xAD4AB7112EB3929D'u, lo: 0x86C16C98D2C953C7'u),
+      uint64x2(hi: 0xD89D64D57A607744'u, lo: 0xE871C7BF077BA8B8'u),
+      uint64x2(hi: 0x87625F056C7C4A8B'u, lo: 0x11471CD764AD4973'u),
+      uint64x2(hi: 0xA93AF6C6C79B5D2D'u, lo: 0xD598E40D3DD89BD0'u),
+      uint64x2(hi: 0xD389B47879823479'u, lo: 0x4AFF1D108D4EC2C4'u),
+      uint64x2(hi: 0x843610CB4BF160CB'u, lo: 0xCEDF722A585139BB'u),
+      uint64x2(hi: 0xA54394FE1EEDB8FE'u, lo: 0xC2974EB4EE658829'u),
+      uint64x2(hi: 0xCE947A3DA6A9273E'u, lo: 0x733D226229FEEA33'u),
+      uint64x2(hi: 0x811CCC668829B887'u, lo: 0x0806357D5A3F5260'u),
+      uint64x2(hi: 0xA163FF802A3426A8'u, lo: 0xCA07C2DCB0CF26F8'u),
+      uint64x2(hi: 0xC9BCFF6034C13052'u, lo: 0xFC89B393DD02F0B6'u),
+      uint64x2(hi: 0xFC2C3F3841F17C67'u, lo: 0xBBAC2078D443ACE3'u),
+      uint64x2(hi: 0x9D9BA7832936EDC0'u, lo: 0xD54B944B84AA4C0E'u),
+      uint64x2(hi: 0xC5029163F384A931'u, lo: 0x0A9E795E65D4DF12'u),
+      uint64x2(hi: 0xF64335BCF065D37D'u, lo: 0x4D4617B5FF4A16D6'u),
+      uint64x2(hi: 0x99EA0196163FA42E'u, lo: 0x504BCED1BF8E4E46'u),
+      uint64x2(hi: 0xC06481FB9BCF8D39'u, lo: 0xE45EC2862F71E1D7'u),
+      uint64x2(hi: 0xF07DA27A82C37088'u, lo: 0x5D767327BB4E5A4D'u),
+      uint64x2(hi: 0x964E858C91BA2655'u, lo: 0x3A6A07F8D510F870'u),
+      uint64x2(hi: 0xBBE226EFB628AFEA'u, lo: 0x890489F70A55368C'u),
+      uint64x2(hi: 0xEADAB0ABA3B2DBE5'u, lo: 0x2B45AC74CCEA842F'u),
+      uint64x2(hi: 0x92C8AE6B464FC96F'u, lo: 0x3B0B8BC90012929E'u),
+      uint64x2(hi: 0xB77ADA0617E3BBCB'u, lo: 0x09CE6EBB40173745'u),
+      uint64x2(hi: 0xE55990879DDCAABD'u, lo: 0xCC420A6A101D0516'u),
+      uint64x2(hi: 0x8F57FA54C2A9EAB6'u, lo: 0x9FA946824A12232E'u),
+      uint64x2(hi: 0xB32DF8E9F3546564'u, lo: 0x47939822DC96ABFA'u),
+      uint64x2(hi: 0xDFF9772470297EBD'u, lo: 0x59787E2B93BC56F8'u),
+      uint64x2(hi: 0x8BFBEA76C619EF36'u, lo: 0x57EB4EDB3C55B65B'u),
+      uint64x2(hi: 0xAEFAE51477A06B03'u, lo: 0xEDE622920B6B23F2'u),
+      uint64x2(hi: 0xDAB99E59958885C4'u, lo: 0xE95FAB368E45ECEE'u),
+      uint64x2(hi: 0x88B402F7FD75539B'u, lo: 0x11DBCB0218EBB415'u),
+      uint64x2(hi: 0xAAE103B5FCD2A881'u, lo: 0xD652BDC29F26A11A'u),
+      uint64x2(hi: 0xD59944A37C0752A2'u, lo: 0x4BE76D3346F04960'u),
+      uint64x2(hi: 0x857FCAE62D8493A5'u, lo: 0x6F70A4400C562DDC'u),
+      uint64x2(hi: 0xA6DFBD9FB8E5B88E'u, lo: 0xCB4CCD500F6BB953'u),
+      uint64x2(hi: 0xD097AD07A71F26B2'u, lo: 0x7E2000A41346A7A8'u),
+      uint64x2(hi: 0x825ECC24C873782F'u, lo: 0x8ED400668C0C28C9'u),
+      uint64x2(hi: 0xA2F67F2DFA90563B'u, lo: 0x728900802F0F32FB'u),
+      uint64x2(hi: 0xCBB41EF979346BCA'u, lo: 0x4F2B40A03AD2FFBA'u),
+      uint64x2(hi: 0xFEA126B7D78186BC'u, lo: 0xE2F610C84987BFA9'u),
+      uint64x2(hi: 0x9F24B832E6B0F436'u, lo: 0x0DD9CA7D2DF4D7CA'u),
+      uint64x2(hi: 0xC6EDE63FA05D3143'u, lo: 0x91503D1C79720DBC'u),
+      uint64x2(hi: 0xF8A95FCF88747D94'u, lo: 0x75A44C6397CE912B'u),
+      uint64x2(hi: 0x9B69DBE1B548CE7C'u, lo: 0xC986AFBE3EE11ABB'u),
+      uint64x2(hi: 0xC24452DA229B021B'u, lo: 0xFBE85BADCE996169'u),
+      uint64x2(hi: 0xF2D56790AB41C2A2'u, lo: 0xFAE27299423FB9C4'u),
+      uint64x2(hi: 0x97C560BA6B0919A5'u, lo: 0xDCCD879FC967D41B'u),
+      uint64x2(hi: 0xBDB6B8E905CB600F'u, lo: 0x5400E987BBC1C921'u),
+      uint64x2(hi: 0xED246723473E3813'u, lo: 0x290123E9AAB23B69'u),
+      uint64x2(hi: 0x9436C0760C86E30B'u, lo: 0xF9A0B6720AAF6522'u),
+      uint64x2(hi: 0xB94470938FA89BCE'u, lo: 0xF808E40E8D5B3E6A'u),
+      uint64x2(hi: 0xE7958CB87392C2C2'u, lo: 0xB60B1D1230B20E05'u),
+      uint64x2(hi: 0x90BD77F3483BB9B9'u, lo: 0xB1C6F22B5E6F48C3'u),
+      uint64x2(hi: 0xB4ECD5F01A4AA828'u, lo: 0x1E38AEB6360B1AF4'u),
+      uint64x2(hi: 0xE2280B6C20DD5232'u, lo: 0x25C6DA63C38DE1B1'u),
+      uint64x2(hi: 0x8D590723948A535F'u, lo: 0x579C487E5A38AD0F'u),
+      uint64x2(hi: 0xB0AF48EC79ACE837'u, lo: 0x2D835A9DF0C6D852'u),
+      uint64x2(hi: 0xDCDB1B2798182244'u, lo: 0xF8E431456CF88E66'u),
+      uint64x2(hi: 0x8A08F0F8BF0F156B'u, lo: 0x1B8E9ECB641B5900'u),
+      uint64x2(hi: 0xAC8B2D36EED2DAC5'u, lo: 0xE272467E3D222F40'u),
+      uint64x2(hi: 0xD7ADF884AA879177'u, lo: 0x5B0ED81DCC6ABB10'u),
+      uint64x2(hi: 0x86CCBB52EA94BAEA'u, lo: 0x98E947129FC2B4EA'u),
+      uint64x2(hi: 0xA87FEA27A539E9A5'u, lo: 0x3F2398D747B36225'u),
+      uint64x2(hi: 0xD29FE4B18E88640E'u, lo: 0x8EEC7F0D19A03AAE'u),
+      uint64x2(hi: 0x83A3EEEEF9153E89'u, lo: 0x1953CF68300424AD'u),
+      uint64x2(hi: 0xA48CEAAAB75A8E2B'u, lo: 0x5FA8C3423C052DD8'u),
+      uint64x2(hi: 0xCDB02555653131B6'u, lo: 0x3792F412CB06794E'u),
+      uint64x2(hi: 0x808E17555F3EBF11'u, lo: 0xE2BBD88BBEE40BD1'u),
+      uint64x2(hi: 0xA0B19D2AB70E6ED6'u, lo: 0x5B6ACEAEAE9D0EC5'u),
+      uint64x2(hi: 0xC8DE047564D20A8B'u, lo: 0xF245825A5A445276'u),
+      uint64x2(hi: 0xFB158592BE068D2E'u, lo: 0xEED6E2F0F0D56713'u),
+      uint64x2(hi: 0x9CED737BB6C4183D'u, lo: 0x55464DD69685606C'u),
+      uint64x2(hi: 0xC428D05AA4751E4C'u, lo: 0xAA97E14C3C26B887'u),
+      uint64x2(hi: 0xF53304714D9265DF'u, lo: 0xD53DD99F4B3066A9'u),
+      uint64x2(hi: 0x993FE2C6D07B7FAB'u, lo: 0xE546A8038EFE402A'u),
+      uint64x2(hi: 0xBF8FDB78849A5F96'u, lo: 0xDE98520472BDD034'u),
+      uint64x2(hi: 0xEF73D256A5C0F77C'u, lo: 0x963E66858F6D4441'u),
+      uint64x2(hi: 0x95A8637627989AAD'u, lo: 0xDDE7001379A44AA9'u),
+      uint64x2(hi: 0xBB127C53B17EC159'u, lo: 0x5560C018580D5D53'u),
+      uint64x2(hi: 0xE9D71B689DDE71AF'u, lo: 0xAAB8F01E6E10B4A7'u),
+      uint64x2(hi: 0x9226712162AB070D'u, lo: 0xCAB3961304CA70E9'u),
+      uint64x2(hi: 0xB6B00D69BB55C8D1'u, lo: 0x3D607B97C5FD0D23'u),
+      uint64x2(hi: 0xE45C10C42A2B3B05'u, lo: 0x8CB89A7DB77C506B'u),
+      uint64x2(hi: 0x8EB98A7A9A5B04E3'u, lo: 0x77F3608E92ADB243'u),
+      uint64x2(hi: 0xB267ED1940F1C61C'u, lo: 0x55F038B237591ED4'u),
+      uint64x2(hi: 0xDF01E85F912E37A3'u, lo: 0x6B6C46DEC52F6689'u),
+      uint64x2(hi: 0x8B61313BBABCE2C6'u, lo: 0x2323AC4B3B3DA016'u),
+      uint64x2(hi: 0xAE397D8AA96C1B77'u, lo: 0xABEC975E0A0D081B'u),
+      uint64x2(hi: 0xD9C7DCED53C72255'u, lo: 0x96E7BD358C904A22'u),
+      uint64x2(hi: 0x881CEA14545C7575'u, lo: 0x7E50D64177DA2E55'u),
+      uint64x2(hi: 0xAA242499697392D2'u, lo: 0xDDE50BD1D5D0B9EA'u),
+      uint64x2(hi: 0xD4AD2DBFC3D07787'u, lo: 0x955E4EC64B44E865'u),
+      uint64x2(hi: 0x84EC3C97DA624AB4'u, lo: 0xBD5AF13BEF0B113F'u),
+      uint64x2(hi: 0xA6274BBDD0FADD61'u, lo: 0xECB1AD8AEACDD58F'u),
+      uint64x2(hi: 0xCFB11EAD453994BA'u, lo: 0x67DE18EDA5814AF3'u),
+      uint64x2(hi: 0x81CEB32C4B43FCF4'u, lo: 0x80EACF948770CED8'u),
+      uint64x2(hi: 0xA2425FF75E14FC31'u, lo: 0xA1258379A94D028E'u),
+      uint64x2(hi: 0xCAD2F7F5359A3B3E'u, lo: 0x096EE45813A04331'u),
+      uint64x2(hi: 0xFD87B5F28300CA0D'u, lo: 0x8BCA9D6E188853FD'u),
+      uint64x2(hi: 0x9E74D1B791E07E48'u, lo: 0x775EA264CF55347E'u),
+      uint64x2(hi: 0xC612062576589DDA'u, lo: 0x95364AFE032A819E'u),
+      uint64x2(hi: 0xF79687AED3EEC551'u, lo: 0x3A83DDBD83F52205'u),
+      uint64x2(hi: 0x9ABE14CD44753B52'u, lo: 0xC4926A9672793543'u),
+      uint64x2(hi: 0xC16D9A0095928A27'u, lo: 0x75B7053C0F178294'u),
+      uint64x2(hi: 0xF1C90080BAF72CB1'u, lo: 0x5324C68B12DD6339'u),
+      uint64x2(hi: 0x971DA05074DA7BEE'u, lo: 0xD3F6FC16EBCA5E04'u),
+      uint64x2(hi: 0xBCE5086492111AEA'u, lo: 0x88F4BB1CA6BCF585'u),
+      uint64x2(hi: 0xEC1E4A7DB69561A5'u, lo: 0x2B31E9E3D06C32E6'u),
+      uint64x2(hi: 0x9392EE8E921D5D07'u, lo: 0x3AFF322E62439FD0'u),
+      uint64x2(hi: 0xB877AA3236A4B449'u, lo: 0x09BEFEB9FAD487C3'u),
+      uint64x2(hi: 0xE69594BEC44DE15B'u, lo: 0x4C2EBE687989A9B4'u),
+      uint64x2(hi: 0x901D7CF73AB0ACD9'u, lo: 0x0F9D37014BF60A11'u),
+      uint64x2(hi: 0xB424DC35095CD80F'u, lo: 0x538484C19EF38C95'u),
+      uint64x2(hi: 0xE12E13424BB40E13'u, lo: 0x2865A5F206B06FBA'u),
+      uint64x2(hi: 0x8CBCCC096F5088CB'u, lo: 0xF93F87B7442E45D4'u),
+      uint64x2(hi: 0xAFEBFF0BCB24AAFE'u, lo: 0xF78F69A51539D749'u),
+      uint64x2(hi: 0xDBE6FECEBDEDD5BE'u, lo: 0xB573440E5A884D1C'u),
+      uint64x2(hi: 0x89705F4136B4A597'u, lo: 0x31680A88F8953031'u),
+      uint64x2(hi: 0xABCC77118461CEFC'u, lo: 0xFDC20D2B36BA7C3E'u),
+      uint64x2(hi: 0xD6BF94D5E57A42BC'u, lo: 0x3D32907604691B4D'u),
+      uint64x2(hi: 0x8637BD05AF6C69B5'u, lo: 0xA63F9A49C2C1B110'u),
+      uint64x2(hi: 0xA7C5AC471B478423'u, lo: 0x0FCF80DC33721D54'u),
+      uint64x2(hi: 0xD1B71758E219652B'u, lo: 0xD3C36113404EA4A9'u),
+      uint64x2(hi: 0x83126E978D4FDF3B'u, lo: 0x645A1CAC083126EA'u),
+      uint64x2(hi: 0xA3D70A3D70A3D70A'u, lo: 0x3D70A3D70A3D70A4'u),
+      uint64x2(hi: 0xCCCCCCCCCCCCCCCC'u, lo: 0xCCCCCCCCCCCCCCCD'u),
+      uint64x2(hi: 0x8000000000000000'u, lo: 0x0000000000000000'u),
+      uint64x2(hi: 0xA000000000000000'u, lo: 0x0000000000000000'u),
+      uint64x2(hi: 0xC800000000000000'u, lo: 0x0000000000000000'u),
+      uint64x2(hi: 0xFA00000000000000'u, lo: 0x0000000000000000'u),
+      uint64x2(hi: 0x9C40000000000000'u, lo: 0x0000000000000000'u),
+      uint64x2(hi: 0xC350000000000000'u, lo: 0x0000000000000000'u),
+      uint64x2(hi: 0xF424000000000000'u, lo: 0x0000000000000000'u),
+      uint64x2(hi: 0x9896800000000000'u, lo: 0x0000000000000000'u),
+      uint64x2(hi: 0xBEBC200000000000'u, lo: 0x0000000000000000'u),
+      uint64x2(hi: 0xEE6B280000000000'u, lo: 0x0000000000000000'u),
+      uint64x2(hi: 0x9502F90000000000'u, lo: 0x0000000000000000'u),
+      uint64x2(hi: 0xBA43B74000000000'u, lo: 0x0000000000000000'u),
+      uint64x2(hi: 0xE8D4A51000000000'u, lo: 0x0000000000000000'u),
+      uint64x2(hi: 0x9184E72A00000000'u, lo: 0x0000000000000000'u),
+      uint64x2(hi: 0xB5E620F480000000'u, lo: 0x0000000000000000'u),
+      uint64x2(hi: 0xE35FA931A0000000'u, lo: 0x0000000000000000'u),
+      uint64x2(hi: 0x8E1BC9BF04000000'u, lo: 0x0000000000000000'u),
+      uint64x2(hi: 0xB1A2BC2EC5000000'u, lo: 0x0000000000000000'u),
+      uint64x2(hi: 0xDE0B6B3A76400000'u, lo: 0x0000000000000000'u),
+      uint64x2(hi: 0x8AC7230489E80000'u, lo: 0x0000000000000000'u),
+      uint64x2(hi: 0xAD78EBC5AC620000'u, lo: 0x0000000000000000'u),
+      uint64x2(hi: 0xD8D726B7177A8000'u, lo: 0x0000000000000000'u),
+      uint64x2(hi: 0x878678326EAC9000'u, lo: 0x0000000000000000'u),
+      uint64x2(hi: 0xA968163F0A57B400'u, lo: 0x0000000000000000'u),
+      uint64x2(hi: 0xD3C21BCECCEDA100'u, lo: 0x0000000000000000'u),
+      uint64x2(hi: 0x84595161401484A0'u, lo: 0x0000000000000000'u),
+      uint64x2(hi: 0xA56FA5B99019A5C8'u, lo: 0x0000000000000000'u),
+      uint64x2(hi: 0xCECB8F27F4200F3A'u, lo: 0x0000000000000000'u),
+      uint64x2(hi: 0x813F3978F8940984'u, lo: 0x4000000000000000'u),
+      uint64x2(hi: 0xA18F07D736B90BE5'u, lo: 0x5000000000000000'u),
+      uint64x2(hi: 0xC9F2C9CD04674EDE'u, lo: 0xA400000000000000'u),
+      uint64x2(hi: 0xFC6F7C4045812296'u, lo: 0x4D00000000000000'u),
+      uint64x2(hi: 0x9DC5ADA82B70B59D'u, lo: 0xF020000000000000'u),
+      uint64x2(hi: 0xC5371912364CE305'u, lo: 0x6C28000000000000'u),
+      uint64x2(hi: 0xF684DF56C3E01BC6'u, lo: 0xC732000000000000'u),
+      uint64x2(hi: 0x9A130B963A6C115C'u, lo: 0x3C7F400000000000'u),
+      uint64x2(hi: 0xC097CE7BC90715B3'u, lo: 0x4B9F100000000000'u),
+      uint64x2(hi: 0xF0BDC21ABB48DB20'u, lo: 0x1E86D40000000000'u),
+      uint64x2(hi: 0x96769950B50D88F4'u, lo: 0x1314448000000000'u),
+      uint64x2(hi: 0xBC143FA4E250EB31'u, lo: 0x17D955A000000000'u),
+      uint64x2(hi: 0xEB194F8E1AE525FD'u, lo: 0x5DCFAB0800000000'u),
+      uint64x2(hi: 0x92EFD1B8D0CF37BE'u, lo: 0x5AA1CAE500000000'u),
+      uint64x2(hi: 0xB7ABC627050305AD'u, lo: 0xF14A3D9E40000000'u),
+      uint64x2(hi: 0xE596B7B0C643C719'u, lo: 0x6D9CCD05D0000000'u),
+      uint64x2(hi: 0x8F7E32CE7BEA5C6F'u, lo: 0xE4820023A2000000'u),
+      uint64x2(hi: 0xB35DBF821AE4F38B'u, lo: 0xDDA2802C8A800000'u),
+      uint64x2(hi: 0xE0352F62A19E306E'u, lo: 0xD50B2037AD200000'u),
+      uint64x2(hi: 0x8C213D9DA502DE45'u, lo: 0x4526F422CC340000'u),
+      uint64x2(hi: 0xAF298D050E4395D6'u, lo: 0x9670B12B7F410000'u),
+      uint64x2(hi: 0xDAF3F04651D47B4C'u, lo: 0x3C0CDD765F114000'u),
+      uint64x2(hi: 0x88D8762BF324CD0F'u, lo: 0xA5880A69FB6AC800'u),
+      uint64x2(hi: 0xAB0E93B6EFEE0053'u, lo: 0x8EEA0D047A457A00'u),
+      uint64x2(hi: 0xD5D238A4ABE98068'u, lo: 0x72A4904598D6D880'u),
+      uint64x2(hi: 0x85A36366EB71F041'u, lo: 0x47A6DA2B7F864750'u),
+      uint64x2(hi: 0xA70C3C40A64E6C51'u, lo: 0x999090B65F67D924'u),
+      uint64x2(hi: 0xD0CF4B50CFE20765'u, lo: 0xFFF4B4E3F741CF6D'u),
+      uint64x2(hi: 0x82818F1281ED449F'u, lo: 0xBFF8F10E7A8921A4'u),
+      uint64x2(hi: 0xA321F2D7226895C7'u, lo: 0xAFF72D52192B6A0D'u),
+      uint64x2(hi: 0xCBEA6F8CEB02BB39'u, lo: 0x9BF4F8A69F764490'u),
+      uint64x2(hi: 0xFEE50B7025C36A08'u, lo: 0x02F236D04753D5B4'u),
+      uint64x2(hi: 0x9F4F2726179A2245'u, lo: 0x01D762422C946590'u),
+      uint64x2(hi: 0xC722F0EF9D80AAD6'u, lo: 0x424D3AD2B7B97EF5'u),
+      uint64x2(hi: 0xF8EBAD2B84E0D58B'u, lo: 0xD2E0898765A7DEB2'u),
+      uint64x2(hi: 0x9B934C3B330C8577'u, lo: 0x63CC55F49F88EB2F'u),
+      uint64x2(hi: 0xC2781F49FFCFA6D5'u, lo: 0x3CBF6B71C76B25FB'u),
+      uint64x2(hi: 0xF316271C7FC3908A'u, lo: 0x8BEF464E3945EF7A'u),
+      uint64x2(hi: 0x97EDD871CFDA3A56'u, lo: 0x97758BF0E3CBB5AC'u),
+      uint64x2(hi: 0xBDE94E8E43D0C8EC'u, lo: 0x3D52EEED1CBEA317'u),
+      uint64x2(hi: 0xED63A231D4C4FB27'u, lo: 0x4CA7AAA863EE4BDD'u),
+      uint64x2(hi: 0x945E455F24FB1CF8'u, lo: 0x8FE8CAA93E74EF6A'u),
+      uint64x2(hi: 0xB975D6B6EE39E436'u, lo: 0xB3E2FD538E122B44'u),
+      uint64x2(hi: 0xE7D34C64A9C85D44'u, lo: 0x60DBBCA87196B616'u),
+      uint64x2(hi: 0x90E40FBEEA1D3A4A'u, lo: 0xBC8955E946FE31CD'u),
+      uint64x2(hi: 0xB51D13AEA4A488DD'u, lo: 0x6BABAB6398BDBE41'u),
+      uint64x2(hi: 0xE264589A4DCDAB14'u, lo: 0xC696963C7EED2DD1'u),
+      uint64x2(hi: 0x8D7EB76070A08AEC'u, lo: 0xFC1E1DE5CF543CA2'u),
+      uint64x2(hi: 0xB0DE65388CC8ADA8'u, lo: 0x3B25A55F43294BCB'u),
+      uint64x2(hi: 0xDD15FE86AFFAD912'u, lo: 0x49EF0EB713F39EBE'u),
+      uint64x2(hi: 0x8A2DBF142DFCC7AB'u, lo: 0x6E3569326C784337'u),
+      uint64x2(hi: 0xACB92ED9397BF996'u, lo: 0x49C2C37F07965404'u),
+      uint64x2(hi: 0xD7E77A8F87DAF7FB'u, lo: 0xDC33745EC97BE906'u),
+      uint64x2(hi: 0x86F0AC99B4E8DAFD'u, lo: 0x69A028BB3DED71A3'u),
+      uint64x2(hi: 0xA8ACD7C0222311BC'u, lo: 0xC40832EA0D68CE0C'u),
+      uint64x2(hi: 0xD2D80DB02AABD62B'u, lo: 0xF50A3FA490C30190'u),
+      uint64x2(hi: 0x83C7088E1AAB65DB'u, lo: 0x792667C6DA79E0FA'u),
+      uint64x2(hi: 0xA4B8CAB1A1563F52'u, lo: 0x577001B891185938'u),
+      uint64x2(hi: 0xCDE6FD5E09ABCF26'u, lo: 0xED4C0226B55E6F86'u),
+      uint64x2(hi: 0x80B05E5AC60B6178'u, lo: 0x544F8158315B05B4'u),
+      uint64x2(hi: 0xA0DC75F1778E39D6'u, lo: 0x696361AE3DB1C721'u),
+      uint64x2(hi: 0xC913936DD571C84C'u, lo: 0x03BC3A19CD1E38E9'u),
+      uint64x2(hi: 0xFB5878494ACE3A5F'u, lo: 0x04AB48A04065C723'u),
+      uint64x2(hi: 0x9D174B2DCEC0E47B'u, lo: 0x62EB0D64283F9C76'u),
+      uint64x2(hi: 0xC45D1DF942711D9A'u, lo: 0x3BA5D0BD324F8394'u),
+      uint64x2(hi: 0xF5746577930D6500'u, lo: 0xCA8F44EC7EE36479'u),
+      uint64x2(hi: 0x9968BF6ABBE85F20'u, lo: 0x7E998B13CF4E1ECB'u),
+      uint64x2(hi: 0xBFC2EF456AE276E8'u, lo: 0x9E3FEDD8C321A67E'u),
+      uint64x2(hi: 0xEFB3AB16C59B14A2'u, lo: 0xC5CFE94EF3EA101E'u),
+      uint64x2(hi: 0x95D04AEE3B80ECE5'u, lo: 0xBBA1F1D158724A12'u),
+      uint64x2(hi: 0xBB445DA9CA61281F'u, lo: 0x2A8A6E45AE8EDC97'u),
+      uint64x2(hi: 0xEA1575143CF97226'u, lo: 0xF52D09D71A3293BD'u),
+      uint64x2(hi: 0x924D692CA61BE758'u, lo: 0x593C2626705F9C56'u),
+      uint64x2(hi: 0xB6E0C377CFA2E12E'u, lo: 0x6F8B2FB00C77836C'u),
+      uint64x2(hi: 0xE498F455C38B997A'u, lo: 0x0B6DFB9C0F956447'u),
+      uint64x2(hi: 0x8EDF98B59A373FEC'u, lo: 0x4724BD4189BD5EAC'u),
+      uint64x2(hi: 0xB2977EE300C50FE7'u, lo: 0x58EDEC91EC2CB657'u),
+      uint64x2(hi: 0xDF3D5E9BC0F653E1'u, lo: 0x2F2967B66737E3ED'u),
+      uint64x2(hi: 0x8B865B215899F46C'u, lo: 0xBD79E0D20082EE74'u),
+      uint64x2(hi: 0xAE67F1E9AEC07187'u, lo: 0xECD8590680A3AA11'u),
+      uint64x2(hi: 0xDA01EE641A708DE9'u, lo: 0xE80E6F4820CC9495'u),
+      uint64x2(hi: 0x884134FE908658B2'u, lo: 0x3109058D147FDCDD'u),
+      uint64x2(hi: 0xAA51823E34A7EEDE'u, lo: 0xBD4B46F0599FD415'u),
+      uint64x2(hi: 0xD4E5E2CDC1D1EA96'u, lo: 0x6C9E18AC7007C91A'u),
+      uint64x2(hi: 0x850FADC09923329E'u, lo: 0x03E2CF6BC604DDB0'u),
+      uint64x2(hi: 0xA6539930BF6BFF45'u, lo: 0x84DB8346B786151C'u),
+      uint64x2(hi: 0xCFE87F7CEF46FF16'u, lo: 0xE612641865679A63'u),
+      uint64x2(hi: 0x81F14FAE158C5F6E'u, lo: 0x4FCB7E8F3F60C07E'u),
+      uint64x2(hi: 0xA26DA3999AEF7749'u, lo: 0xE3BE5E330F38F09D'u),
+      uint64x2(hi: 0xCB090C8001AB551C'u, lo: 0x5CADF5BFD3072CC5'u),
+      uint64x2(hi: 0xFDCB4FA002162A63'u, lo: 0x73D9732FC7C8F7F6'u),
+      uint64x2(hi: 0x9E9F11C4014DDA7E'u, lo: 0x2867E7FDDCDD9AFA'u),
+      uint64x2(hi: 0xC646D63501A1511D'u, lo: 0xB281E1FD541501B8'u),
+      uint64x2(hi: 0xF7D88BC24209A565'u, lo: 0x1F225A7CA91A4226'u),
+      uint64x2(hi: 0x9AE757596946075F'u, lo: 0x3375788DE9B06958'u),
+      uint64x2(hi: 0xC1A12D2FC3978937'u, lo: 0x0052D6B1641C83AE'u),
+      uint64x2(hi: 0xF209787BB47D6B84'u, lo: 0xC0678C5DBD23A49A'u),
+      uint64x2(hi: 0x9745EB4D50CE6332'u, lo: 0xF840B7BA963646E0'u),
+      uint64x2(hi: 0xBD176620A501FBFF'u, lo: 0xB650E5A93BC3D898'u),
+      uint64x2(hi: 0xEC5D3FA8CE427AFF'u, lo: 0xA3E51F138AB4CEBE'u),
+      uint64x2(hi: 0x93BA47C980E98CDF'u, lo: 0xC66F336C36B10137'u),
+      uint64x2(hi: 0xB8A8D9BBE123F017'u, lo: 0xB80B0047445D4184'u),
+      uint64x2(hi: 0xE6D3102AD96CEC1D'u, lo: 0xA60DC059157491E5'u),
+      uint64x2(hi: 0x9043EA1AC7E41392'u, lo: 0x87C89837AD68DB2F'u),
+      uint64x2(hi: 0xB454E4A179DD1877'u, lo: 0x29BABE4598C311FB'u),
+      uint64x2(hi: 0xE16A1DC9D8545E94'u, lo: 0xF4296DD6FEF3D67A'u),
+      uint64x2(hi: 0x8CE2529E2734BB1D'u, lo: 0x1899E4A65F58660C'u),
+      uint64x2(hi: 0xB01AE745B101E9E4'u, lo: 0x5EC05DCFF72E7F8F'u),
+      uint64x2(hi: 0xDC21A1171D42645D'u, lo: 0x76707543F4FA1F73'u),
+      uint64x2(hi: 0x899504AE72497EBA'u, lo: 0x6A06494A791C53A8'u),
+      uint64x2(hi: 0xABFA45DA0EDBDE69'u, lo: 0x0487DB9D17636892'u),
+      uint64x2(hi: 0xD6F8D7509292D603'u, lo: 0x45A9D2845D3C42B6'u),
+      uint64x2(hi: 0x865B86925B9BC5C2'u, lo: 0x0B8A2392BA45A9B2'u),
+      uint64x2(hi: 0xA7F26836F282B732'u, lo: 0x8E6CAC7768D7141E'u),
+      uint64x2(hi: 0xD1EF0244AF2364FF'u, lo: 0x3207D795430CD926'u),
+      uint64x2(hi: 0x8335616AED761F1F'u, lo: 0x7F44E6BD49E807B8'u),
+      uint64x2(hi: 0xA402B9C5A8D3A6E7'u, lo: 0x5F16206C9C6209A6'u),
+      uint64x2(hi: 0xCD036837130890A1'u, lo: 0x36DBA887C37A8C0F'u),
+      uint64x2(hi: 0x802221226BE55A64'u, lo: 0xC2494954DA2C9789'u),
+      uint64x2(hi: 0xA02AA96B06DEB0FD'u, lo: 0xF2DB9BAA10B7BD6C'u),
+      uint64x2(hi: 0xC83553C5C8965D3D'u, lo: 0x6F92829494E5ACC7'u),
+      uint64x2(hi: 0xFA42A8B73ABBF48C'u, lo: 0xCB772339BA1F17F9'u),
+      uint64x2(hi: 0x9C69A97284B578D7'u, lo: 0xFF2A760414536EFB'u),
+      uint64x2(hi: 0xC38413CF25E2D70D'u, lo: 0xFEF5138519684ABA'u),
+      uint64x2(hi: 0xF46518C2EF5B8CD1'u, lo: 0x7EB258665FC25D69'u),
+      uint64x2(hi: 0x98BF2F79D5993802'u, lo: 0xEF2F773FFBD97A61'u),
+      uint64x2(hi: 0xBEEEFB584AFF8603'u, lo: 0xAAFB550FFACFD8FA'u),
+      uint64x2(hi: 0xEEAABA2E5DBF6784'u, lo: 0x95BA2A53F983CF38'u),
+      uint64x2(hi: 0x952AB45CFA97A0B2'u, lo: 0xDD945A747BF26183'u),
+      uint64x2(hi: 0xBA756174393D88DF'u, lo: 0x94F971119AEEF9E4'u),
+      uint64x2(hi: 0xE912B9D1478CEB17'u, lo: 0x7A37CD5601AAB85D'u),
+      uint64x2(hi: 0x91ABB422CCB812EE'u, lo: 0xAC62E055C10AB33A'u),
+      uint64x2(hi: 0xB616A12B7FE617AA'u, lo: 0x577B986B314D6009'u),
+      uint64x2(hi: 0xE39C49765FDF9D94'u, lo: 0xED5A7E85FDA0B80B'u),
+      uint64x2(hi: 0x8E41ADE9FBEBC27D'u, lo: 0x14588F13BE847307'u),
+      uint64x2(hi: 0xB1D219647AE6B31C'u, lo: 0x596EB2D8AE258FC8'u),
+      uint64x2(hi: 0xDE469FBD99A05FE3'u, lo: 0x6FCA5F8ED9AEF3BB'u),
+      uint64x2(hi: 0x8AEC23D680043BEE'u, lo: 0x25DE7BB9480D5854'u),
+      uint64x2(hi: 0xADA72CCC20054AE9'u, lo: 0xAF561AA79A10AE6A'u),
+      uint64x2(hi: 0xD910F7FF28069DA4'u, lo: 0x1B2BA1518094DA04'u),
+      uint64x2(hi: 0x87AA9AFF79042286'u, lo: 0x90FB44D2F05D0842'u),
+      uint64x2(hi: 0xA99541BF57452B28'u, lo: 0x353A1607AC744A53'u),
+      uint64x2(hi: 0xD3FA922F2D1675F2'u, lo: 0x42889B8997915CE8'u),
+      uint64x2(hi: 0x847C9B5D7C2E09B7'u, lo: 0x69956135FEBADA11'u),
+      uint64x2(hi: 0xA59BC234DB398C25'u, lo: 0x43FAB9837E699095'u),
+      uint64x2(hi: 0xCF02B2C21207EF2E'u, lo: 0x94F967E45E03F4BB'u),
+      uint64x2(hi: 0x8161AFB94B44F57D'u, lo: 0x1D1BE0EEBAC278F5'u),
+      uint64x2(hi: 0xA1BA1BA79E1632DC'u, lo: 0x6462D92A69731732'u),
+      uint64x2(hi: 0xCA28A291859BBF93'u, lo: 0x7D7B8F7503CFDCFE'u),
+      uint64x2(hi: 0xFCB2CB35E702AF78'u, lo: 0x5CDA735244C3D43E'u),
+      uint64x2(hi: 0x9DEFBF01B061ADAB'u, lo: 0x3A0888136AFA64A7'u),
+      uint64x2(hi: 0xC56BAEC21C7A1916'u, lo: 0x088AAA1845B8FDD0'u),
+      uint64x2(hi: 0xF6C69A72A3989F5B'u, lo: 0x8AAD549E57273D45'u),
+      uint64x2(hi: 0x9A3C2087A63F6399'u, lo: 0x36AC54E2F678864B'u),
+      uint64x2(hi: 0xC0CB28A98FCF3C7F'u, lo: 0x84576A1BB416A7DD'u),
+      uint64x2(hi: 0xF0FDF2D3F3C30B9F'u, lo: 0x656D44A2A11C51D5'u),
+      uint64x2(hi: 0x969EB7C47859E743'u, lo: 0x9F644AE5A4B1B325'u),
+      uint64x2(hi: 0xBC4665B596706114'u, lo: 0x873D5D9F0DDE1FEE'u),
+      uint64x2(hi: 0xEB57FF22FC0C7959'u, lo: 0xA90CB506D155A7EA'u),
+      uint64x2(hi: 0x9316FF75DD87CBD8'u, lo: 0x09A7F12442D588F2'u),
+      uint64x2(hi: 0xB7DCBF5354E9BECE'u, lo: 0x0C11ED6D538AEB2F'u),
+      uint64x2(hi: 0xE5D3EF282A242E81'u, lo: 0x8F1668C8A86DA5FA'u),
+      uint64x2(hi: 0x8FA475791A569D10'u, lo: 0xF96E017D694487BC'u),
+      uint64x2(hi: 0xB38D92D760EC4455'u, lo: 0x37C981DCC395A9AC'u),
+      uint64x2(hi: 0xE070F78D3927556A'u, lo: 0x85BBE253F47B1417'u),
+      uint64x2(hi: 0x8C469AB843B89562'u, lo: 0x93956D7478CCEC8E'u),
+      uint64x2(hi: 0xAF58416654A6BABB'u, lo: 0x387AC8D1970027B2'u),
+      uint64x2(hi: 0xDB2E51BFE9D0696A'u, lo: 0x06997B05FCC0319E'u),
+      uint64x2(hi: 0x88FCF317F22241E2'u, lo: 0x441FECE3BDF81F03'u),
+      uint64x2(hi: 0xAB3C2FDDEEAAD25A'u, lo: 0xD527E81CAD7626C3'u),
+      uint64x2(hi: 0xD60B3BD56A5586F1'u, lo: 0x8A71E223D8D3B074'u),
+      uint64x2(hi: 0x85C7056562757456'u, lo: 0xF6872D5667844E49'u),
+      uint64x2(hi: 0xA738C6BEBB12D16C'u, lo: 0xB428F8AC016561DB'u),
+      uint64x2(hi: 0xD106F86E69D785C7'u, lo: 0xE13336D701BEBA52'u),
+      uint64x2(hi: 0x82A45B450226B39C'u, lo: 0xECC0024661173473'u),
+      uint64x2(hi: 0xA34D721642B06084'u, lo: 0x27F002D7F95D0190'u),
+      uint64x2(hi: 0xCC20CE9BD35C78A5'u, lo: 0x31EC038DF7B441F4'u),
+      uint64x2(hi: 0xFF290242C83396CE'u, lo: 0x7E67047175A15271'u),
+      uint64x2(hi: 0x9F79A169BD203E41'u, lo: 0x0F0062C6E984D386'u),
+      uint64x2(hi: 0xC75809C42C684DD1'u, lo: 0x52C07B78A3E60868'u),
+      uint64x2(hi: 0xF92E0C3537826145'u, lo: 0xA7709A56CCDF8A82'u),
+      uint64x2(hi: 0x9BBCC7A142B17CCB'u, lo: 0x88A66076400BB691'u),
+      uint64x2(hi: 0xC2ABF989935DDBFE'u, lo: 0x6ACFF893D00EA435'u),
+      uint64x2(hi: 0xF356F7EBF83552FE'u, lo: 0x0583F6B8C4124D43'u),
+      uint64x2(hi: 0x98165AF37B2153DE'u, lo: 0xC3727A337A8B704A'u),
+      uint64x2(hi: 0xBE1BF1B059E9A8D6'u, lo: 0x744F18C0592E4C5C'u),
+      uint64x2(hi: 0xEDA2EE1C7064130C'u, lo: 0x1162DEF06F79DF73'u),
+      uint64x2(hi: 0x9485D4D1C63E8BE7'u, lo: 0x8ADDCB5645AC2BA8'u),
+      uint64x2(hi: 0xB9A74A0637CE2EE1'u, lo: 0x6D953E2BD7173692'u),
+      uint64x2(hi: 0xE8111C87C5C1BA99'u, lo: 0xC8FA8DB6CCDD0437'u),
+      uint64x2(hi: 0x910AB1D4DB9914A0'u, lo: 0x1D9C9892400A22A2'u),
+      uint64x2(hi: 0xB54D5E4A127F59C8'u, lo: 0x2503BEB6D00CAB4B'u),
+      uint64x2(hi: 0xE2A0B5DC971F303A'u, lo: 0x2E44AE64840FD61D'u),
+      uint64x2(hi: 0x8DA471A9DE737E24'u, lo: 0x5CEAECFED289E5D2'u),
+      uint64x2(hi: 0xB10D8E1456105DAD'u, lo: 0x7425A83E872C5F47'u),
+      uint64x2(hi: 0xDD50F1996B947518'u, lo: 0xD12F124E28F77719'u),
+      uint64x2(hi: 0x8A5296FFE33CC92F'u, lo: 0x82BD6B70D99AAA6F'u),
+      uint64x2(hi: 0xACE73CBFDC0BFB7B'u, lo: 0x636CC64D1001550B'u),
+      uint64x2(hi: 0xD8210BEFD30EFA5A'u, lo: 0x3C47F7E05401AA4E'u),
+      uint64x2(hi: 0x8714A775E3E95C78'u, lo: 0x65ACFAEC34810A71'u),
+      uint64x2(hi: 0xA8D9D1535CE3B396'u, lo: 0x7F1839A741A14D0D'u),
+      uint64x2(hi: 0xD31045A8341CA07C'u, lo: 0x1EDE48111209A050'u),
+      uint64x2(hi: 0x83EA2B892091E44D'u, lo: 0x934AED0AAB460432'u),
+      uint64x2(hi: 0xA4E4B66B68B65D60'u, lo: 0xF81DA84D5617853F'u),
+      uint64x2(hi: 0xCE1DE40642E3F4B9'u, lo: 0x36251260AB9D668E'u),
+      uint64x2(hi: 0x80D2AE83E9CE78F3'u, lo: 0xC1D72B7C6B426019'u),
+      uint64x2(hi: 0xA1075A24E4421730'u, lo: 0xB24CF65B8612F81F'u),
+      uint64x2(hi: 0xC94930AE1D529CFC'u, lo: 0xDEE033F26797B627'u),
+      uint64x2(hi: 0xFB9B7CD9A4A7443C'u, lo: 0x169840EF017DA3B1'u),
+      uint64x2(hi: 0x9D412E0806E88AA5'u, lo: 0x8E1F289560EE864E'u),
+      uint64x2(hi: 0xC491798A08A2AD4E'u, lo: 0xF1A6F2BAB92A27E2'u),
+      uint64x2(hi: 0xF5B5D7EC8ACB58A2'u, lo: 0xAE10AF696774B1DB'u),
+      uint64x2(hi: 0x9991A6F3D6BF1765'u, lo: 0xACCA6DA1E0A8EF29'u),
+      uint64x2(hi: 0xBFF610B0CC6EDD3F'u, lo: 0x17FD090A58D32AF3'u),
+      uint64x2(hi: 0xEFF394DCFF8A948E'u, lo: 0xDDFC4B4CEF07F5B0'u),
+      uint64x2(hi: 0x95F83D0A1FB69CD9'u, lo: 0x4ABDAF101564F98E'u),
+      uint64x2(hi: 0xBB764C4CA7A4440F'u, lo: 0x9D6D1AD41ABE37F1'u),
+      uint64x2(hi: 0xEA53DF5FD18D5513'u, lo: 0x84C86189216DC5ED'u),
+      uint64x2(hi: 0x92746B9BE2F8552C'u, lo: 0x32FD3CF5B4E49BB4'u),
+      uint64x2(hi: 0xB7118682DBB66A77'u, lo: 0x3FBC8C33221DC2A1'u),
+      uint64x2(hi: 0xE4D5E82392A40515'u, lo: 0x0FABAF3FEAA5334A'u),
+      uint64x2(hi: 0x8F05B1163BA6832D'u, lo: 0x29CB4D87F2A7400E'u),
+      uint64x2(hi: 0xB2C71D5BCA9023F8'u, lo: 0x743E20E9EF511012'u),
+      uint64x2(hi: 0xDF78E4B2BD342CF6'u, lo: 0x914DA9246B255416'u),
+      uint64x2(hi: 0x8BAB8EEFB6409C1A'u, lo: 0x1AD089B6C2F7548E'u),
+      uint64x2(hi: 0xAE9672ABA3D0C320'u, lo: 0xA184AC2473B529B1'u),
+      uint64x2(hi: 0xDA3C0F568CC4F3E8'u, lo: 0xC9E5D72D90A2741E'u),
+      uint64x2(hi: 0x8865899617FB1871'u, lo: 0x7E2FA67C7A658892'u),
+      uint64x2(hi: 0xAA7EEBFB9DF9DE8D'u, lo: 0xDDBB901B98FEEAB7'u),
+      uint64x2(hi: 0xD51EA6FA85785631'u, lo: 0x552A74227F3EA565'u),
+      uint64x2(hi: 0x8533285C936B35DE'u, lo: 0xD53A88958F87275F'u),
+      uint64x2(hi: 0xA67FF273B8460356'u, lo: 0x8A892ABAF368F137'u),
+      uint64x2(hi: 0xD01FEF10A657842C'u, lo: 0x2D2B7569B0432D85'u),
+      uint64x2(hi: 0x8213F56A67F6B29B'u, lo: 0x9C3B29620E29FC73'u),
+      uint64x2(hi: 0xA298F2C501F45F42'u, lo: 0x8349F3BA91B47B8F'u),
+      uint64x2(hi: 0xCB3F2F7642717713'u, lo: 0x241C70A936219A73'u),
+      uint64x2(hi: 0xFE0EFB53D30DD4D7'u, lo: 0xED238CD383AA0110'u),
+      uint64x2(hi: 0x9EC95D1463E8A506'u, lo: 0xF4363804324A40AA'u),
+      uint64x2(hi: 0xC67BB4597CE2CE48'u, lo: 0xB143C6053EDCD0D5'u),
+      uint64x2(hi: 0xF81AA16FDC1B81DA'u, lo: 0xDD94B7868E94050A'u),
+      uint64x2(hi: 0x9B10A4E5E9913128'u, lo: 0xCA7CF2B4191C8326'u),
+      uint64x2(hi: 0xC1D4CE1F63F57D72'u, lo: 0xFD1C2F611F63A3F0'u),
+      uint64x2(hi: 0xF24A01A73CF2DCCF'u, lo: 0xBC633B39673C8CEC'u),
+      uint64x2(hi: 0x976E41088617CA01'u, lo: 0xD5BE0503E085D813'u),
+      uint64x2(hi: 0xBD49D14AA79DBC82'u, lo: 0x4B2D8644D8A74E18'u),
+      uint64x2(hi: 0xEC9C459D51852BA2'u, lo: 0xDDF8E7D60ED1219E'u),
+      uint64x2(hi: 0x93E1AB8252F33B45'u, lo: 0xCABB90E5C942B503'u),
+      uint64x2(hi: 0xB8DA1662E7B00A17'u, lo: 0x3D6A751F3B936243'u),
+      uint64x2(hi: 0xE7109BFBA19C0C9D'u, lo: 0x0CC512670A783AD4'u),
+      uint64x2(hi: 0x906A617D450187E2'u, lo: 0x27FB2B80668B24C5'u),
+      uint64x2(hi: 0xB484F9DC9641E9DA'u, lo: 0xB1F9F660802DEDF6'u),
+      uint64x2(hi: 0xE1A63853BBD26451'u, lo: 0x5E7873F8A0396973'u),
+      uint64x2(hi: 0x8D07E33455637EB2'u, lo: 0xDB0B487B6423E1E8'u),
+      uint64x2(hi: 0xB049DC016ABC5E5F'u, lo: 0x91CE1A9A3D2CDA62'u),
+      uint64x2(hi: 0xDC5C5301C56B75F7'u, lo: 0x7641A140CC7810FB'u),
+      uint64x2(hi: 0x89B9B3E11B6329BA'u, lo: 0xA9E904C87FCB0A9D'u),
+      uint64x2(hi: 0xAC2820D9623BF429'u, lo: 0x546345FA9FBDCD44'u),
+      uint64x2(hi: 0xD732290FBACAF133'u, lo: 0xA97C177947AD4095'u),
+      uint64x2(hi: 0x867F59A9D4BED6C0'u, lo: 0x49ED8EABCCCC485D'u),
+      uint64x2(hi: 0xA81F301449EE8C70'u, lo: 0x5C68F256BFFF5A74'u),
+      uint64x2(hi: 0xD226FC195C6A2F8C'u, lo: 0x73832EEC6FFF3111'u),
+      uint64x2(hi: 0x83585D8FD9C25DB7'u, lo: 0xC831FD53C5FF7EAB'u),
+      uint64x2(hi: 0xA42E74F3D032F525'u, lo: 0xBA3E7CA8B77F5E55'u),
+      uint64x2(hi: 0xCD3A1230C43FB26F'u, lo: 0x28CE1BD2E55F35EB'u),
+      uint64x2(hi: 0x80444B5E7AA7CF85'u, lo: 0x7980D163CF5B81B3'u),
+      uint64x2(hi: 0xA0555E361951C366'u, lo: 0xD7E105BCC332621F'u),
+      uint64x2(hi: 0xC86AB5C39FA63440'u, lo: 0x8DD9472BF3FEFAA7'u),
+      uint64x2(hi: 0xFA856334878FC150'u, lo: 0xB14F98F6F0FEB951'u),
+      uint64x2(hi: 0x9C935E00D4B9D8D2'u, lo: 0x6ED1BF9A569F33D3'u),
+      uint64x2(hi: 0xC3B8358109E84F07'u, lo: 0x0A862F80EC4700C8'u),
+      uint64x2(hi: 0xF4A642E14C6262C8'u, lo: 0xCD27BB612758C0FA'u),
+      uint64x2(hi: 0x98E7E9CCCFBD7DBD'u, lo: 0x8038D51CB897789C'u),
+      uint64x2(hi: 0xBF21E44003ACDD2C'u, lo: 0xE0470A63E6BD56C3'u),
+      uint64x2(hi: 0xEEEA5D5004981478'u, lo: 0x1858CCFCE06CAC74'u),
+      uint64x2(hi: 0x95527A5202DF0CCB'u, lo: 0x0F37801E0C43EBC8'u),
+      uint64x2(hi: 0xBAA718E68396CFFD'u, lo: 0xD30560258F54E6BA'u),
+      uint64x2(hi: 0xE950DF20247C83FD'u, lo: 0x47C6B82EF32A2069'u),
+      uint64x2(hi: 0x91D28B7416CDD27E'u, lo: 0x4CDC331D57FA5441'u),
+      uint64x2(hi: 0xB6472E511C81471D'u, lo: 0xE0133FE4ADF8E952'u),
+      uint64x2(hi: 0xE3D8F9E563A198E5'u, lo: 0x58180FDDD97723A6'u),
+      uint64x2(hi: 0x8E679C2F5E44FF8F'u, lo: 0x570F09EAA7EA7648'u),
+      uint64x2(hi: 0xB201833B35D63F73'u, lo: 0x2CD2CC6551E513DA'u),
+      uint64x2(hi: 0xDE81E40A034BCF4F'u, lo: 0xF8077F7EA65E58D1'u),
+      uint64x2(hi: 0x8B112E86420F6191'u, lo: 0xFB04AFAF27FAF782'u),
+      uint64x2(hi: 0xADD57A27D29339F6'u, lo: 0x79C5DB9AF1F9B563'u),
+      uint64x2(hi: 0xD94AD8B1C7380874'u, lo: 0x18375281AE7822BC'u),
+      uint64x2(hi: 0x87CEC76F1C830548'u, lo: 0x8F2293910D0B15B5'u),
+      uint64x2(hi: 0xA9C2794AE3A3C69A'u, lo: 0xB2EB3875504DDB22'u),
+      uint64x2(hi: 0xD433179D9C8CB841'u, lo: 0x5FA60692A46151EB'u),
+      uint64x2(hi: 0x849FEEC281D7F328'u, lo: 0xDBC7C41BA6BCD333'u),
+      uint64x2(hi: 0xA5C7EA73224DEFF3'u, lo: 0x12B9B522906C0800'u),
+      uint64x2(hi: 0xCF39E50FEAE16BEF'u, lo: 0xD768226B34870A00'u),
+      uint64x2(hi: 0x81842F29F2CCE375'u, lo: 0xE6A1158300D46640'u),
+      uint64x2(hi: 0xA1E53AF46F801C53'u, lo: 0x60495AE3C1097FD0'u),
+      uint64x2(hi: 0xCA5E89B18B602368'u, lo: 0x385BB19CB14BDFC4'u),
+      uint64x2(hi: 0xFCF62C1DEE382C42'u, lo: 0x46729E03DD9ED7B5'u),
+      uint64x2(hi: 0x9E19DB92B4E31BA9'u, lo: 0x6C07A2C26A8346D1'u),
+      uint64x2(hi: 0xC5A05277621BE293'u, lo: 0xC7098B7305241885'u),
+      uint64x2(hi: 0xF70867153AA2DB38'u, lo: 0xB8CBEE4FC66D1EA7'u)]
+  dragonbox_Assert(k >= kMin)
+  dragonbox_Assert(k <= kMax)
+  return pow10[k - kMin]
+
+##  Returns whether value is divisible by 2^e2
+
+proc multipleOfPow2*(value: uint64; e2: int32): bool {.inline.} =
+  dragonbox_Assert(e2 >= 0)
+  return e2 < 64 and (value and ((uint64(1) shl e2) - 1)) == 0
+
+##  Returns whether value is divisible by 5^e5
+
+proc multipleOfPow5*(value: uint64; e5: int32): bool {.inline.} =
+  type
+    MulCmp {.bycopy.} = object
+      mul: uint64
+      cmp: uint64
+
+  const
+    mod5 = [MulCmp(mul: 0x0000000000000001'u, cmp: 0xFFFFFFFFFFFFFFFF'u),
+      MulCmp(mul: 0xCCCCCCCCCCCCCCCD'u, cmp: 0x3333333333333333'u),
+      MulCmp(mul: 0x8F5C28F5C28F5C29'u, cmp: 0x0A3D70A3D70A3D70'u),
+      MulCmp(mul: 0x1CAC083126E978D5'u, cmp: 0x020C49BA5E353F7C'u),
+      MulCmp(mul: 0xD288CE703AFB7E91'u, cmp: 0x0068DB8BAC710CB2'u),
+      MulCmp(mul: 0x5D4E8FB00BCBE61D'u, cmp: 0x0014F8B588E368F0'u),
+      MulCmp(mul: 0x790FB65668C26139'u, cmp: 0x000431BDE82D7B63'u),
+      MulCmp(mul: 0xE5032477AE8D46A5'u, cmp: 0x0000D6BF94D5E57A'u),
+      MulCmp(mul: 0xC767074B22E90E21'u, cmp: 0x00002AF31DC46118'u),
+      MulCmp(mul: 0x8E47CE423A2E9C6D'u, cmp: 0x0000089705F4136B'u),
+      MulCmp(mul: 0x4FA7F60D3ED61F49'u, cmp: 0x000001B7CDFD9D7B'u),
+      MulCmp(mul: 0x0FEE64690C913975'u, cmp: 0x00000057F5FF85E5'u),
+      MulCmp(mul: 0x3662E0E1CF503EB1'u, cmp: 0x000000119799812D'u),
+      MulCmp(mul: 0xA47A2CF9F6433FBD'u, cmp: 0x0000000384B84D09'u),
+      MulCmp(mul: 0x54186F653140A659'u, cmp: 0x00000000B424DC35'u),
+      MulCmp(mul: 0x7738164770402145'u, cmp: 0x0000000024075F3D'u),
+      MulCmp(mul: 0xE4A4D1417CD9A041'u, cmp: 0x000000000734ACA5'u),
+      MulCmp(mul: 0xC75429D9E5C5200D'u, cmp: 0x000000000170EF54'u),
+      MulCmp(mul: 0xC1773B91FAC10669'u, cmp: 0x000000000049C977'u),
+      MulCmp(mul: 0x26B172506559CE15'u, cmp: 0x00000000000EC1E4'u),
+      MulCmp(mul: 0xD489E3A9ADDEC2D1'u, cmp: 0x000000000002F394'u),
+      MulCmp(mul: 0x90E860BB892C8D5D'u, cmp: 0x000000000000971D'u),
+      MulCmp(mul: 0x502E79BF1B6F4F79'u, cmp: 0x0000000000001E39'u),
+      MulCmp(mul: 0xDCD618596BE30FE5'u, cmp: 0x000000000000060B'u),
+      MulCmp(mul: 0x2C2AD1AB7BFA3661'u, cmp: 0x0000000000000135'u)]
+  dragonbox_Assert(e5 >= 0)
+  dragonbox_Assert(e5 <= 24)
+  let m5: MulCmp = mod5[e5]
+  return value * m5.mul <= m5.cmp
+
+type
+  FloatingDecimal64* {.bycopy.} = object
+    significand*: uint64
+    exponent*: int32
+
+
+proc toDecimal64AsymmetricInterval*(e2: int32): FloatingDecimal64 {.inline.} =
+  ##  NB:
+  ##  accept_lower_endpoint = true
+  ##  accept_upper_endpoint = true
+  const
+    P: int32 = significandSize
+  ##  Compute k and beta
+  let minusK: int32 = floorLog10ThreeQuartersPow2(e2)
+  let betaMinus1: int32 = e2 + floorLog2Pow10(-minusK)
+  ##  Compute xi and zi
+  let pow10: uint64x2 = computePow10(-minusK)
+  let lowerEndpoint: uint64 = (pow10.hi - (pow10.hi shr (P + 1))) shr
+      (64 - P - betaMinus1)
+  let upperEndpoint: uint64 = (pow10.hi + (pow10.hi shr (P + 0))) shr
+      (64 - P - betaMinus1)
+  ##  If we don't accept the left endpoint (but we do!) or
+  ##  if the left endpoint is not an integer, increase it
+  let lowerEndpointIsInteger: bool = (2 <= e2 and e2 <= 3)
+  let xi: uint64 = lowerEndpoint + uint64(not lowerEndpointIsInteger)
+  let zi: uint64 = upperEndpoint
+  ##  Try bigger divisor
+  var q: uint64 = zi div 10
+  if q * 10 >= xi:
+    return FloatingDecimal64(significand: q, exponent: minusK + 1)
+  q = ((pow10.hi shr (64 - (P + 1) - betaMinus1)) + 1) div 2
+  ##  When tie occurs, choose one of them according to the rule
+  if e2 == -77:
+    dec(q, ord(q mod 2 != 0))
+    ##  Round to even.
+  else:
+    inc(q, ord(q < xi))
+  return FloatingDecimal64(significand: q, exponent: minusK)
+
+proc computeDelta*(pow10: uint64x2; betaMinus1: int32): uint32 {.inline.} =
+  dragonbox_Assert(betaMinus1 >= 0)
+  dragonbox_Assert(betaMinus1 <= 63)
+  return cast[uint32](pow10.hi shr (64 - 1 - betaMinus1))
+
+when defined(sizeof_Int128):
+  proc mul128*(x: uint64; y: uint64): uint64x2 {.inline.} =
+    ##  1 mulx
+    type
+      uint128T = uint128
+    let p: uint128T = uint128T(x) * y
+    let hi: uint64 = cast[uint64](p shr 64)
+    let lo: uint64 = cast[uint64](p)
+    return (hi, lo)
+
+elif defined(vcc) and defined(cpu64):
+  proc umul128(x, y: uint64, z: ptr uint64): uint64 {.importc: "_umul128", header: "<intrin.h>".}
+  proc mul128*(x: uint64; y: uint64): uint64x2 {.inline.} =
+    var hi: uint64 = 0
+    var lo: uint64 = umul128(x, y, addr(hi))
+    return uint64x2(hi: hi, lo: lo)
+
+else:
+  proc lo32*(x: uint64): uint32 {.inline.} =
+    return cast[uint32](x)
+
+  proc hi32*(x: uint64): uint32 {.inline.} =
+    return cast[uint32](x shr 32)
+
+  proc mul128*(a: uint64; b: uint64): uint64x2 {.inline.} =
+    let b00: uint64 = uint64(lo32(a)) * lo32(b)
+    let b01: uint64 = uint64(lo32(a)) * hi32(b)
+    let b10: uint64 = uint64(hi32(a)) * lo32(b)
+    let b11: uint64 = uint64(hi32(a)) * hi32(b)
+    let mid1: uint64 = b10 + hi32(b00)
+    let mid2: uint64 = b01 + lo32(mid1)
+    let hi: uint64 = b11 + hi32(mid1) + hi32(mid2)
+    let lo: uint64 = lo32(b00) or uint64(lo32(mid2)) shl 32
+    return uint64x2(hi: hi, lo: lo)
+
+##  Returns (x * y) / 2^128
+
+proc mulShift*(x: uint64; y: uint64x2): uint64 {.inline.} =
+  ##  2 mulx
+  var p1: uint64x2 = mul128(x, y.hi)
+  var p0: uint64x2 = mul128(x, y.lo)
+  p1.lo += p0.hi
+  inc(p1.hi, ord(p1.lo < p0.hi))
+  return p1.hi
+
+proc mulParity*(twoF: uint64; pow10: uint64x2; betaMinus1: int32): bool {.inline.} =
+  ##  1 mulx, 1 mul
+  dragonbox_Assert(betaMinus1 >= 1)
+  dragonbox_Assert(betaMinus1 <= 63)
+  let p01: uint64 = twoF * pow10.hi
+  let p10: uint64 = mul128(twoF, pow10.lo).hi
+  let mid: uint64 = p01 + p10
+  return (mid and (uint64(1) shl (64 - betaMinus1))) != 0
+
+proc isIntegralEndpoint*(twoF: uint64; e2: int32; minusK: int32): bool {.inline.} =
+  if e2 < -2:
+    return false
+  if e2 <= 9:
+    return true
+  if e2 <= 86:
+    return multipleOfPow5(twoF, minusK)
+  return false
+
+proc isIntegralMidpoint*(twoF: uint64; e2: int32; minusK: int32): bool {.inline.} =
+  if e2 < -4:
+    return multipleOfPow2(twoF, minusK - e2 + 1)
+  if e2 <= 9:
+    return true
+  if e2 <= 86:
+    return multipleOfPow5(twoF, minusK)
+  return false
+
+proc toDecimal64*(ieeeSignificand: uint64; ieeeExponent: uint64): FloatingDecimal64 {.
+    inline.} =
+  const
+    kappa: int32 = 2
+  const
+    bigDivisor: uint32 = 1000
+  ##  10^(kappa + 1)
+  const
+    smallDivisor: uint32 = 100
+  ##  10^(kappa)
+  ##
+  ##  Step 1:
+  ##  integer promotion & Schubfach multiplier calculation.
+  ##
+  var m2: uint64
+  var e2: int32
+  if ieeeExponent != 0:
+    m2 = hiddenBit or ieeeSignificand
+    e2 = cast[int32](ieeeExponent) - exponentBias
+    if 0 <= -e2 and -e2 < significandSize and multipleOfPow2(m2, -e2):
+      ##  Small integer.
+      return FloatingDecimal64(significand: m2 shr -e2, exponent: 0)
+    if ieeeSignificand == 0 and ieeeExponent > 1:
+      ##  Shorter interval case; proceed like Schubfach.
+      return toDecimal64AsymmetricInterval(e2)
+  else:
+    ##  Subnormal case; interval is always regular.
+    m2 = ieeeSignificand
+    e2 = 1 - exponentBias
+  let isEven: bool = (m2 mod 2 == 0)
+  let acceptLower: bool = isEven
+  let acceptUpper: bool = isEven
+  ##  Compute k and beta.
+  let minusK: int32 = floorLog10Pow2(e2) - kappa
+  let betaMinus1: int32 = e2 + floorLog2Pow10(-minusK)
+  dragonbox_Assert(betaMinus1 >= 6)
+  dragonbox_Assert(betaMinus1 <= 9)
+  let pow10: uint64x2 = computePow10(-minusK)
+  ##  Compute delta
+  ##  10^kappa <= delta < 10^(kappa + 1)
+  ##       100 <= delta < 1000
+  let delta: uint32 = computeDelta(pow10, betaMinus1)
+  dragonbox_Assert(delta >= smallDivisor)
+  dragonbox_Assert(delta < bigDivisor)
+  let twoFl: uint64 = 2 * m2 - 1
+  let twoFc: uint64 = 2 * m2
+  let twoFr: uint64 = 2 * m2 + 1
+  ##  (54 bits)
+  ##  Compute zi
+  ##   (54 + 9 = 63 bits)
+  let zi: uint64 = mulShift(twoFr shl betaMinus1, pow10)
+  ##  2 mulx
+  ##
+  ##  Step 2:
+  ##  Try larger divisor.
+  ##
+  var q: uint64 = zi div bigDivisor
+  ##   uint64_t q = Mul128(zi, 0x83126E978D4FDF3Cu).hi >> 9; // 1 mulx
+  var r: uint32 = cast[uint32](zi) - bigDivisor * cast[uint32](q)
+  ##  r = zi % BigDivisor
+  ##  0 <= r < 1000
+  if r < delta:                  ## likely ~50% ?!
+            ##  (r > deltai)
+    ##  Exclude the right endpoint if necessary
+    if r != 0 or acceptUpper or not isIntegralEndpoint(twoFr, e2, minusK):
+      return FloatingDecimal64(significand: q, exponent: minusK + kappa + 1)
+    dragonbox_Assert(q != 0)
+    dec(q)
+    r = bigDivisor
+  elif r == delta:               ## unlikely
+    ##  Compare fractional parts.
+    ##  Check conditions in the order different from the paper
+    ##  to take advantage of short-circuiting
+    if (acceptLower and isIntegralEndpoint(twoFl, e2, minusK)) or
+        mulParity(twoFl, pow10, betaMinus1):
+      return FloatingDecimal64(significand: q, exponent: minusK + kappa + 1)
+  else:
+    discard
+  ##
+  ##  Step 3:
+  ##  Find the significand with the smaller divisor
+  ##
+  q = q * 10
+  ##  1 hmul
+  ##  0 <= r <= 1000
+  let dist: uint32 = r - (delta div 2) + (smallDivisor div 2)
+  let distQ: uint32 = dist div 100
+  ##  1 mul
+  ##   const uint32_t dist_r = dist % 100;
+  q += distQ
+  ##   if /*likely*/ (dist_r == 0)
+  if dist == distQ * 100:
+    ##       const bool approx_y_parity = ((dist ^ (SmallDivisor / 2)) & 1) != 0;
+    let approxYParity: bool = (dist and 1) != 0
+    ##  Check z^(f) >= epsilon^(f)
+    ##  We have either yi == zi - epsiloni or yi == (zi - epsiloni) - 1,
+    ##  where yi == zi - epsiloni if and only if z^(f) >= epsilon^(f)
+    ##  Since there are only 2 possibilities, we only need to care about the
+    ##  parity. Also, zi and r should have the same parity since the divisor
+    ##  is an even number
+    if mulParity(twoFc, pow10, betaMinus1) != approxYParity:
+      dec(q)
+    elif q mod 2 != 0 and isIntegralMidpoint(twoFc, e2, minusK):
+      dec(q)
+  return FloatingDecimal64(significand: q, exponent: minusK + kappa)
+
+# ==================================================================================================
+#  ToChars
+# ==================================================================================================
+
+when false:
+  template `+!`(x: cstring; offset: int): cstring = cast[cstring](cast[uint](x) + uint(offset))
+
+  template dec(x: cstring; offset=1) = x = cast[cstring](cast[uint](x) - uint(offset))
+  template inc(x: cstring; offset=1) = x = cast[cstring](cast[uint](x) + uint(offset))
+
+  proc memset(x: cstring; ch: char; L: int) {.importc, nodecl.}
+  proc memmove(a, b: cstring; L: int) {.importc, nodecl.}
+
+proc utoa8DigitsSkipTrailingZeros*(buf: var openArray[char]; pos: int; digits: uint32): int {.inline.} =
+  dragonbox_Assert(digits >= 1)
+  dragonbox_Assert(digits <= 99999999'u32)
+  let q: uint32 = digits div 10000
+  let r: uint32 = digits mod 10000
+  let qH: uint32 = q div 100
+  let qL: uint32 = q mod 100
+  utoa2Digits(buf, pos, qH)
+  utoa2Digits(buf, pos + 2, qL)
+  if r == 0:
+    return trailingZeros2Digits(if qL == 0: qH else: qL) + (if qL == 0: 6 else: 4)
+  else:
+    let rH: uint32 = r div 100
+    let rL: uint32 = r mod 100
+    utoa2Digits(buf, pos + 4, rH)
+    utoa2Digits(buf, pos + 6, rL)
+    return trailingZeros2Digits(if rL == 0: rH else: rL) + (if rL == 0: 2 else: 0)
+
+proc printDecimalDigitsBackwards*(buf: var openArray[char]; pos: int; output64: uint64): int {.inline.} =
+  var pos = pos
+  var output64 = output64
+  var tz = 0
+  ##  number of trailing zeros removed.
+  var nd = 0
+  ##  number of decimal digits processed.
+  ##  At most 17 digits remaining
+  if output64 >= 100000000'u64:
+    let q: uint64 = output64 div 100000000'u64
+    let r: uint32 = cast[uint32](output64 mod 100000000'u64)
+    output64 = q
+    dec(pos, 8)
+    if r != 0:
+      tz = utoa8DigitsSkipTrailingZeros(buf, pos, r)
+      dragonbox_Assert(tz >= 0)
+      dragonbox_Assert(tz <= 7)
+    else:
+      tz = 8
+    nd = 8
+  dragonbox_Assert(output64 <= high(uint32))
+  var output = cast[uint32](output64)
+  if output >= 10000:
+    let q: uint32 = output div 10000
+    let r: uint32 = output mod 10000
+    output = q
+    dec(pos, 4)
+    if r != 0:
+      let rH: uint32 = r div 100
+      let rL: uint32 = r mod 100
+      utoa2Digits(buf, pos, rH)
+      utoa2Digits(buf, pos + 2, rL)
+      if tz == nd:
+        inc(tz, trailingZeros2Digits(if rL == 0: rH else: rL) +
+            (if rL == 0: 2 else: 0))
+    else:
+      if tz == nd:
+        inc(tz, 4)
+      else:
+        for i in 0..3: buf[pos+i] = '0'
+      ##  (actually not required...)
+    inc(nd, 4)
+  if output >= 100:
+    let q: uint32 = output div 100
+    let r: uint32 = output mod 100
+    output = q
+    dec(pos, 2)
+    utoa2Digits(buf, pos, r)
+    if tz == nd:
+      inc(tz, trailingZeros2Digits(r))
+    inc(nd, 2)
+    if output >= 100:
+      let q2: uint32 = output div 100
+      let r2: uint32 = output mod 100
+      output = q2
+      dec(pos, 2)
+      utoa2Digits(buf, pos, r2)
+      if tz == nd:
+        inc(tz, trailingZeros2Digits(r2))
+      inc(nd, 2)
+  dragonbox_Assert(output >= 1)
+  dragonbox_Assert(output <= 99)
+  if output >= 10:
+    let q: uint32 = output
+    dec(pos, 2)
+    utoa2Digits(buf, pos, q)
+    if tz == nd:
+      inc(tz, trailingZeros2Digits(q))
+  else:
+    let q: uint32 = output
+    dragonbox_Assert(q >= 1)
+    dragonbox_Assert(q <= 9)
+    dec(pos)
+    buf[pos] = chr(ord('0') + q)
+  return tz
+
+proc decimalLength*(v: uint64): int {.inline.} =
+  dragonbox_Assert(v >= 1)
+  dragonbox_Assert(v <= 99999999999999999'u64)
+  if cast[uint32](v shr 32) != 0:
+    if v >= 10000000000000000'u64:
+      return 17
+    if v >= 1000000000000000'u64:
+      return 16
+    if v >= 100000000000000'u64:
+      return 15
+    if v >= 10000000000000'u64:
+      return 14
+    if v >= 1000000000000'u64:
+      return 13
+    if v >= 100000000000'u64:
+      return 12
+    if v >= 10000000000'u64:
+      return 11
+    return 10
+  let v32: uint32 = cast[uint32](v)
+  if v32 >= 1000000000'u32:
+    return 10
+  if v32 >= 100000000'u32:
+    return 9
+  if v32 >= 10000000'u32:
+    return 8
+  if v32 >= 1000000'u32:
+    return 7
+  if v32 >= 100000'u32:
+    return 6
+  if v32 >= 10000'u32:
+    return 5
+  if v32 >= 1000'u32:
+    return 4
+  if v32 >= 100'u32:
+    return 3
+  if v32 >= 10'u32:
+    return 2
+  return 1
+
+proc formatDigits*[T: Ordinal](buffer: var openArray[char]; pos: T; digits: uint64; decimalExponent: int;
+                  forceTrailingDotZero = false): int {.inline.} =
+  const
+    minFixedDecimalPoint = -6
+  const
+    maxFixedDecimalPoint = 17
+  var pos:int = pos.int
+  assert(minFixedDecimalPoint <= -1, "internal error")
+  assert(maxFixedDecimalPoint >= 17, "internal error")
+  dragonbox_Assert(digits >= 1)
+  dragonbox_Assert(digits <= 99999999999999999'u64)
+  dragonbox_Assert(decimalExponent >= -999)
+  dragonbox_Assert(decimalExponent <= 999)
+  var numDigits = decimalLength(digits)
+  let decimalPoint = numDigits + decimalExponent
+  let useFixed: bool = minFixedDecimalPoint <= decimalPoint and
+      decimalPoint <= maxFixedDecimalPoint
+  ## Prepare the buffer.
+  for i in 0..<32: buffer[pos+i] = '0'
+  assert(minFixedDecimalPoint >= -30, "internal error")
+  assert(maxFixedDecimalPoint <= 32, "internal error")
+  var decimalDigitsPosition: int
+  if useFixed:
+    if decimalPoint <= 0:
+      ##  0.[000]digits
+      decimalDigitsPosition = 2 - decimalPoint
+    else:
+      ##  dig.its
+      ##  digits[000]
+      decimalDigitsPosition = 0
+  else:
+    ##  dE+123 or d.igitsE+123
+    decimalDigitsPosition = 1
+  var digitsEnd = pos + int(decimalDigitsPosition + numDigits)
+  let tz = printDecimalDigitsBackwards(buffer, digitsEnd, digits)
+  dec(digitsEnd, tz)
+  dec(numDigits, tz)
+  ##   decimal_exponent += tz; // => decimal_point unchanged.
+  if useFixed:
+    if decimalPoint <= 0:
+      ##  0.[000]digits
+      buffer[pos+1] = '.'
+      pos = digitsEnd
+    elif decimalPoint < numDigits:
+      ##  dig.its
+      when true: #defined(vcc) and not defined(clang):
+        ##  VC does not inline the memmove call below. (Even if compiled with /arch:AVX2.)
+        ##  However, memcpy will be inlined.
+        var tmp: array[16, char]
+        for i in 0..<16: tmp[i] = buffer[i+pos+decimalPoint]
+        for i in 0..<16: buffer[i+pos+decimalPoint+1] = tmp[i]
+      else:
+        memmove(buffer +! (decimalPoint + 1), buffer +! decimalPoint, 16)
+      buffer[pos+decimalPoint] = '.'
+      pos = digitsEnd + 1
+    else:
+      ##  digits[000]
+      inc(pos, decimalPoint)
+      if forceTrailingDotZero:
+        buffer[pos] = '.'
+        buffer[pos+1] = '0'
+        inc(pos, 2)
+  else:
+    ##  Copy the first digit one place to the left.
+    buffer[pos] = buffer[pos+1]
+    if numDigits == 1:
+      ##  dE+123
+      inc(pos)
+    else:
+      ##  d.igitsE+123
+      buffer[pos+1] = '.'
+      pos = digitsEnd
+    let scientificExponent: int = decimalPoint - 1
+    ##       SF_ASSERT(scientific_exponent != 0);
+    buffer[pos] = 'e'
+    buffer[pos+1] = if scientificExponent < 0: '-' else: '+'
+    inc(pos, 2)
+    let k: uint32 = cast[uint32](if scientificExponent < 0: -scientificExponent else: scientificExponent)
+    if k < 10:
+      buffer[pos] = chr(ord('0') + k)
+      inc(pos)
+    elif k < 100:
+      utoa2Digits(buffer, pos, k)
+      inc(pos, 2)
+    else:
+      let q: uint32 = k div 100
+      let r: uint32 = k mod 100
+      buffer[pos] = chr(ord('0') + q)
+      inc(pos)
+      utoa2Digits(buffer, pos, r)
+      inc(pos, 2)
+  return pos
+
+proc toChars*(buffer: var openArray[char]; v: float; forceTrailingDotZero = false): int {.
+    inline.} =
+  var pos = 0
+  let significand: uint64 = physicalSignificand(constructDouble(v))
+  let exponent: uint64 = physicalExponent(constructDouble(v))
+  if exponent != maxIeeeExponent:
+    ##  Finite
+    buffer[pos] = '-'
+    inc(pos, signBit(constructDouble(v)))
+    if exponent != 0 or significand != 0:
+      ##  != 0
+      let dec = toDecimal64(significand, exponent)
+      return formatDigits(buffer, pos, dec.significand, dec.exponent.int,
+                         forceTrailingDotZero)
+    else:
+      buffer[pos] = '0'
+      buffer[pos+1] = '.'
+      buffer[pos+2] = '0'
+      buffer[pos+3] = ' '
+      inc(pos, if forceTrailingDotZero: 3 else: 1)
+      return pos
+  if significand == 0:
+    buffer[pos] = '-'
+    inc(pos, signBit(constructDouble(v)))
+    buffer[pos] = 'i'
+    buffer[pos+1] = 'n'
+    buffer[pos+2] = 'f'
+    buffer[pos+3] = ' '
+    return pos + 3
+  else:
+    buffer[pos] = 'n'
+    buffer[pos+1] = 'a'
+    buffer[pos+2] = 'n'
+    buffer[pos+3] = ' '
+    return pos + 3
+
+when false:
+  proc toString*(value: float): string =
+    var buffer: array[dtoaMinBufferLength, char]
+    let last = toChars(addr buffer, value)
+    let L = cast[int](last) - cast[int](addr(buffer))
+    result = newString(L)
+    copyMem(addr result[0], addr buffer[0], L)
+
diff --git a/lib/std/private/gitutils.nim b/lib/std/private/gitutils.nim
index bf5e7cb1f..6dc9c8f3b 100644
--- a/lib/std/private/gitutils.nim
+++ b/lib/std/private/gitutils.nim
@@ -4,7 +4,10 @@ internal API for now, API subject to change
 
 # xxx move other git utilities here; candidate for stdlib.
 
-import std/[os, osproc, strutils]
+import std/[os, paths, osproc, strutils, tempfiles]
+
+when defined(nimPreviewSlimSystem):
+  import std/[assertions, syncio]
 
 const commitHead* = "HEAD"
 
@@ -29,12 +32,43 @@ template retryCall*(maxRetry = 3, backoffDuration = 1.0, call: untyped): bool =
   result
 
 proc isGitRepo*(dir: string): bool =
-  ## This command is used to get the relative path to the root of the repository.
-  ## Using this, we can verify whether a folder is a git repository by checking
-  ## whether the command success and if the output is empty.
-  let (output, status) = execCmdEx("git rev-parse --show-cdup", workingDir = dir)
-  # On Windows there will be a trailing newline on success, remove it.
-  # The value of a successful call typically won't have a whitespace (it's
-  # usually a series of ../), so we know that it's safe to unconditionally
-  # remove trailing whitespaces from the result.
-  result = status == 0 and output.strip() == ""
+  ## Avoid calling git since it depends on /bin/sh existing and fails in Nix.
+  return fileExists(dir/".git/HEAD")
+
+proc diffFiles*(path1, path2: string): tuple[output: string, same: bool] =
+  ## Returns a human readable diff of files `path1`, `path2`, the exact form of
+  ## which is implementation defined.
+  # This could be customized, e.g. non-git diff with `diff -uNdr`, or with
+  # git diff options (e.g. --color-moved, --word-diff).
+  # in general, `git diff` has more options than `diff`.
+  var status = 0
+  (result.output, status) = execCmdEx("git diff --no-index $1 $2" % [path1.quoteShell, path2.quoteShell])
+  doAssert (status == 0) or (status == 1)
+  result.same = status == 0
+
+proc diffStrings*(a, b: string): tuple[output: string, same: bool] =
+  ## Returns a human readable diff of `a`, `b`, the exact form of which is
+  ## implementation defined.
+  ## See also `experimental.diff`.
+  runnableExamples:
+    let a = "ok1\nok2\nok3\n"
+    let b = "ok1\nok2 alt\nok3\nok4\n"
+    let (c, same) = diffStrings(a, b)
+    doAssert not same
+    let (c2, same2) = diffStrings(a, a)
+    doAssert same2
+  runnableExamples("-r:off"):
+    let a = "ok1\nok2\nok3\n"
+    let b = "ok1\nok2 alt\nok3\nok4\n"
+    echo diffStrings(a, b).output
+
+  template tmpFileImpl(prefix, str): auto =
+    let path = genTempPath(prefix, "")
+    writeFile(path, str)
+    path
+  let patha = tmpFileImpl("diffStrings_a_", a)
+  let pathb = tmpFileImpl("diffStrings_b_", b)
+  defer:
+    removeFile(patha)
+    removeFile(pathb)
+  result = diffFiles(patha, pathb)
diff --git a/lib/std/private/globs.nim b/lib/std/private/globs.nim
index b98a7808b..a6d088558 100644
--- a/lib/std/private/globs.nim
+++ b/lib/std/private/globs.nim
@@ -4,9 +4,18 @@ this can eventually be moved to std/os and `walkDirRec` can be implemented in te
 to avoid duplication
 ]##
 
-import std/[os]
+import std/os
 when defined(windows):
-  from strutils import replace
+  from std/strutils import replace
+
+when defined(nimPreviewSlimSystem):
+  import std/[assertions, objectdollar]
+
+
+when defined(nimHasEffectsOf):
+  {.experimental: "strictEffects".}
+else:
+  {.pragma: effectsOf.}
 
 type
   PathEntry* = object
@@ -14,7 +23,7 @@ type
     path*: string
 
 iterator walkDirRecFilter*(dir: string, follow: proc(entry: PathEntry): bool = nil,
-    relative = false, checkDir = true): PathEntry {.tags: [ReadDirEffect].} =
+    relative = false, checkDir = true): PathEntry {.tags: [ReadDirEffect], effectsOf: follow.} =
   ## Improved `os.walkDirRec`.
   #[
   note: a yieldFilter isn't needed because caller can filter at call site, without
@@ -45,12 +54,17 @@ iterator walkDirRecFilter*(dir: string, follow: proc(entry: PathEntry): bool = n
 
 proc nativeToUnixPath*(path: string): string =
   # pending https://github.com/nim-lang/Nim/pull/13265
-  doAssert not path.isAbsolute # not implemented here; absolute files need more care for the drive
+  result = path
+  when defined(windows):
+    if path.len >= 2 and path[0] in {'a'..'z', 'A'..'Z'} and path[1] == ':':
+      result[0] = '/'
+      result[1] = path[0]
+      if path.len > 2 and path[2] != '\\':
+        raiseAssert "paths like `C:foo` are currently unsupported, path: " & path
   when DirSep == '\\':
-    result = replace(path, '\\', '/')
-  else: result = path
+    result = replace(result, '\\', '/')
 
 when isMainModule:
-  import sugar
-  for a in walkDirRecFilter(".", follow = a=>a.path.lastPathPart notin ["nimcache", ".git", ".csources", "bin"]):
+  import std/sugar
+  for a in walkDirRecFilter(".", follow = a=>a.path.lastPathPart notin ["nimcache", ".git", "csources_v1", "csources", "bin"]):
     echo a
diff --git a/lib/std/private/jsutils.nim b/lib/std/private/jsutils.nim
index 836b3512a..5f79eab27 100644
--- a/lib/std/private/jsutils.nim
+++ b/lib/std/private/jsutils.nim
@@ -37,13 +37,13 @@ when defined(js):
       let a = array[2, float64].default
       assert jsConstructorName(a) == "Float64Array"
       assert jsConstructorName(a.toJs) == "Float64Array"
-    asm """`result` = `a`.constructor.name"""
+    {.emit: """`result` = `a`.constructor.name;""".}
 
   proc hasJsBigInt*(): bool =
-    asm """`result` = typeof BigInt != 'undefined'"""
+    {.emit: """`result` = typeof BigInt != 'undefined';""".}
 
   proc hasBigUint64Array*(): bool =
-    asm """`result` = typeof BigUint64Array != 'undefined'"""
+    {.emit: """`result` = typeof BigUint64Array != 'undefined';""".}
 
   proc getProtoName*[T](a: T): cstring {.importjs: "Object.prototype.toString.call(#)".} =
     runnableExamples:
@@ -79,5 +79,18 @@ when defined(js):
       assert not "123".toJs.isSafeInteger
       assert 123.isSafeInteger
       assert 123.toJs.isSafeInteger
-      assert 9007199254740991.toJs.isSafeInteger
-      assert not 9007199254740992.toJs.isSafeInteger
+      when false:
+        assert 9007199254740991.toJs.isSafeInteger
+        assert not 9007199254740992.toJs.isSafeInteger
+
+template whenJsNoBigInt64*(no64, yes64): untyped =
+  when defined(js):
+    when compiles(compileOption("jsbigint64")):
+      when compileOption("jsbigint64"):
+        yes64
+      else:
+        no64
+    else:
+      no64
+  else:
+    no64
diff --git a/lib/std/private/miscdollars.nim b/lib/std/private/miscdollars.nim
index a41cf1bc1..06fda6fa1 100644
--- a/lib/std/private/miscdollars.nim
+++ b/lib/std/private/miscdollars.nim
@@ -1,3 +1,5 @@
+from std/private/digitsutils import addInt
+
 template toLocation*(result: var string, file: string | cstring, line: int, col: int) =
   ## avoids spurious allocations
   # Hopefully this can be re-used everywhere so that if a user needs to customize,
@@ -5,11 +7,33 @@ template toLocation*(result: var string, file: string | cstring, line: int, col:
   result.add file
   if line > 0:
     result.add "("
-    # simplify this after moving moving `include strmantle` above import assertions`
-    when declared(addInt): result.addInt line
-    else: result.add $line
+    addInt(result, line)
     if col > 0:
       result.add ", "
-      when declared(addInt): result.addInt col
-      else: result.add $col
+      addInt(result, col)
     result.add ")"
+
+proc isNamedTuple(T: typedesc): bool {.magic: "TypeTrait".}
+
+template tupleObjectDollar*[T: tuple | object](result: var string, x: T) =
+  result = "("
+  const isNamed = T is object or isNamedTuple(typeof(T))
+  var count {.used.} = 0
+  for name, value in fieldPairs(x):
+    if count > 0: result.add(", ")
+    when isNamed:
+      result.add(name)
+      result.add(": ")
+    count.inc
+    when compiles($value):
+      when value isnot string and value isnot seq and compiles(value.isNil):
+        if value.isNil: result.add "nil"
+        else: result.addQuoted(value)
+      else:
+        result.addQuoted(value)
+    else:
+      result.add("...")
+  when not isNamed:
+    if count == 1:
+      result.add(",") # $(1,) should print as the semantically legal (1,)
+  result.add(")")
diff --git a/lib/std/private/ntpath.nim b/lib/std/private/ntpath.nim
new file mode 100644
index 000000000..7c8661bb7
--- /dev/null
+++ b/lib/std/private/ntpath.nim
@@ -0,0 +1,61 @@
+# This module is inspired by Python's `ntpath.py` module.
+
+import std/[
+  strutils,
+]
+
+# Adapted `splitdrive` function from the following commits in Python source
+# code:
+# 5a607a3ee5e81bdcef3f886f9d20c1376a533df4 (2009): Initial UNC handling (by Mark Hammond)
+# 2ba0fd5767577954f331ecbd53596cd8035d7186 (2022): Support for "UNC"-device paths (by Barney Gale)
+#
+# FAQ: Why use `strip` below? `\\?\UNC` is the start of a "UNC symbolic link",
+# which is a special UNC form. Running `strip` differentiates `\\?\UNC\` (a UNC
+# symbolic link) from e.g. `\\?\UNCD` (UNCD is the server in the UNC path).
+func splitDrive*(p: string): tuple[drive, path: string] =
+  ## Splits a Windows path into a drive and path part. The drive can be e.g.
+  ## `C:`. It can also be a UNC path (`\\server\drive\path`).
+  ##
+  ## The equivalent `splitDrive` for POSIX systems always returns empty drive.
+  ## Therefore this proc is only necessary on DOS-like file systems (together
+  ## with Nim's `doslikeFileSystem` conditional variable).
+  ##
+  ## This proc's use case is to extract `path` such that it can be manipulated
+  ## like a POSIX path.
+  runnableExamples:
+    doAssert splitDrive("C:") == ("C:", "")
+    doAssert splitDrive(r"C:\") == (r"C:", r"\")
+    doAssert splitDrive(r"\\server\drive\foo\bar") == (r"\\server\drive", r"\foo\bar")
+    doAssert splitDrive(r"\\?\UNC\server\share\dir") == (r"\\?\UNC\server\share", r"\dir")
+
+  result = ("", p)
+  if p.len < 2:
+    return
+  const sep = '\\'
+  let normp = p.replace('/', sep)
+  if p.len > 2 and normp[0] == sep and normp[1] == sep and normp[2] != sep:
+
+    # is a UNC path:
+    # vvvvvvvvvvvvvvvvvvvv drive letter or UNC path
+    # \\machine\mountpoint\directory\etc\...
+    #           directory ^^^^^^^^^^^^^^^
+    let start = block:
+      const unc = "\\\\?\\UNC" # Length is 7
+      let idx = min(8, normp.len)
+      if unc == normp[0..<idx].strip(chars = {sep}, leading = false).toUpperAscii:
+        8
+      else:
+        2
+    let index = normp.find(sep, start)
+    if index == -1:
+      return
+    var index2 = normp.find(sep, index + 1)
+
+    # a UNC path can't have two slashes in a row (after the initial two)
+    if index2 == index + 1:
+      return
+    if index2 == -1:
+      index2 = p.len
+    return (p[0..<index2], p[index2..^1])
+  if p[1] == ':':
+    return (p[0..1], p[2..^1])
diff --git a/lib/std/private/osappdirs.nim b/lib/std/private/osappdirs.nim
new file mode 100644
index 000000000..07a6809bb
--- /dev/null
+++ b/lib/std/private/osappdirs.nim
@@ -0,0 +1,176 @@
+## .. importdoc:: paths.nim, dirs.nim
+
+include system/inclrtl
+import std/envvars
+import std/private/ospaths2
+
+proc getHomeDir*(): string {.rtl, extern: "nos$1",
+  tags: [ReadEnvEffect, ReadIOEffect].} =
+  ## Returns the home directory of the current user.
+  ##
+  ## This proc is wrapped by the `expandTilde proc`_
+  ## for the convenience of processing paths coming from user configuration files.
+  ##
+  ## See also:
+  ## * `getDataDir proc`_
+  ## * `getConfigDir proc`_
+  ## * `getTempDir proc`_
+  ## * `expandTilde proc`_
+  ## * `getCurrentDir proc`_
+  ## * `setCurrentDir proc`_
+  runnableExamples:
+    import std/os
+    assert getHomeDir() == expandTilde("~")
+
+  when defined(windows): return getEnv("USERPROFILE") & "\\"
+  else: return getEnv("HOME") & "/"
+
+proc getDataDir*(): string {.rtl, extern: "nos$1"
+  tags: [ReadEnvEffect, ReadIOEffect].} =
+  ## Returns the data directory of the current user for applications.
+  ## 
+  ## On non-Windows OSs, this proc conforms to the XDG Base Directory
+  ## spec. Thus, this proc returns the value of the `XDG_DATA_HOME` environment
+  ## variable if it is set, otherwise it returns the default configuration
+  ## directory ("~/.local/share" or "~/Library/Application Support" on macOS).
+  ## 
+  ## See also:
+  ## * `getHomeDir proc`_
+  ## * `getConfigDir proc`_
+  ## * `getTempDir proc`_
+  ## * `expandTilde proc`_
+  ## * `getCurrentDir proc`_
+  ## * `setCurrentDir proc`_
+  when defined(windows):
+    result = getEnv("APPDATA")
+  elif defined(macosx):
+    result = getEnv("XDG_DATA_HOME", getEnv("HOME") / "Library" / "Application Support")
+  else:
+    result = getEnv("XDG_DATA_HOME", getEnv("HOME") / ".local" / "share")
+  result.normalizePathEnd(trailingSep = true)
+
+proc getConfigDir*(): string {.rtl, extern: "nos$1",
+  tags: [ReadEnvEffect, ReadIOEffect].} =
+  ## Returns the config directory of the current user for applications.
+  ##
+  ## On non-Windows OSs, this proc conforms to the XDG Base Directory
+  ## spec. Thus, this proc returns the value of the `XDG_CONFIG_HOME` environment
+  ## variable if it is set, otherwise it returns the default configuration
+  ## directory ("~/.config/").
+  ##
+  ## An OS-dependent trailing slash is always present at the end of the
+  ## returned string: `\\` on Windows and `/` on all other OSs.
+  ##
+  ## See also:
+  ## * `getHomeDir proc`_
+  ## * `getDataDir proc`_
+  ## * `getTempDir proc`_
+  ## * `expandTilde proc`_
+  ## * `getCurrentDir proc`_
+  ## * `setCurrentDir proc`_
+  when defined(windows):
+    result = getEnv("APPDATA")
+  else:
+    result = getEnv("XDG_CONFIG_HOME", getEnv("HOME") / ".config")
+  result.normalizePathEnd(trailingSep = true)
+
+proc getCacheDir*(): string =
+  ## Returns the cache directory of the current user for applications.
+  ##
+  ## This makes use of the following environment variables:
+  ##
+  ## * On Windows: `getEnv("LOCALAPPDATA")`
+  ##
+  ## * On macOS: `getEnv("XDG_CACHE_HOME", getEnv("HOME") / "Library/Caches")`
+  ##
+  ## * On other platforms: `getEnv("XDG_CACHE_HOME", getEnv("HOME") / ".cache")`
+  ##
+  ## **See also:**
+  ## * `getHomeDir proc`_
+  ## * `getTempDir proc`_
+  ## * `getConfigDir proc`_
+  ## * `getDataDir proc`_
+  # follows https://crates.io/crates/platform-dirs
+  when defined(windows):
+    result = getEnv("LOCALAPPDATA")
+  elif defined(osx):
+    result = getEnv("XDG_CACHE_HOME", getEnv("HOME") / "Library/Caches")
+  else:
+    result = getEnv("XDG_CACHE_HOME", getEnv("HOME") / ".cache")
+  result.normalizePathEnd(false)
+
+proc getCacheDir*(app: string): string =
+  ## Returns the cache directory for an application `app`.
+  ##
+  ## * On Windows, this uses: `getCacheDir() / app / "cache"`
+  ## * On other platforms, this uses: `getCacheDir() / app`
+  when defined(windows):
+    getCacheDir() / app / "cache"
+  else:
+    getCacheDir() / app
+
+
+when defined(windows):
+  type DWORD = uint32
+
+  when defined(nimPreviewSlimSystem):
+    import std/widestrs
+
+  proc getTempPath(
+    nBufferLength: DWORD, lpBuffer: WideCString
+  ): DWORD {.stdcall, dynlib: "kernel32.dll", importc: "GetTempPathW".} =
+    ## Retrieves the path of the directory designated for temporary files.
+
+template getEnvImpl(result: var string, tempDirList: openArray[string]) =
+  for dir in tempDirList:
+    if existsEnv(dir):
+      result = getEnv(dir)
+      break
+
+template getTempDirImpl(result: var string) =
+  when defined(windows):
+    getEnvImpl(result, ["TMP", "TEMP", "USERPROFILE"])
+  else:
+    getEnvImpl(result, ["TMPDIR", "TEMP", "TMP", "TEMPDIR"])
+
+proc getTempDir*(): string {.rtl, extern: "nos$1",
+  tags: [ReadEnvEffect, ReadIOEffect].} =
+  ## Returns the temporary directory of the current user for applications to
+  ## save temporary files in.
+  ##
+  ## On Windows, it calls [GetTempPath](https://docs.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-gettemppathw).
+  ## On Posix based platforms, it will check `TMPDIR`, `TEMP`, `TMP` and `TEMPDIR` environment variables in order.
+  ## On all platforms, `/tmp` will be returned if the procs fails.
+  ##
+  ## You can override this implementation
+  ## by adding `-d:tempDir=mytempname` to your compiler invocation.
+  ##
+  ## **Note:** This proc does not check whether the returned path exists.
+  ##
+  ## See also:
+  ## * `getHomeDir proc`_
+  ## * `getConfigDir proc`_
+  ## * `expandTilde proc`_
+  ## * `getCurrentDir proc`_
+  ## * `setCurrentDir proc`_
+  const tempDirDefault = "/tmp"
+  when defined(tempDir):
+    const tempDir {.strdefine.}: string = tempDirDefault
+    result = tempDir
+  else:
+    when nimvm:
+      getTempDirImpl(result)
+    else:
+      when defined(windows):
+        let size = getTempPath(0, nil)
+        # If the function fails, the return value is zero.
+        if size > 0:
+          let buffer = newWideCString(size.int)
+          if getTempPath(size, buffer) > 0:
+            result = $buffer
+      elif defined(android): result = "/data/local/tmp"
+      else:
+        getTempDirImpl(result)
+    if result.len == 0:
+      result = tempDirDefault
+  normalizePathEnd(result, trailingSep=true)
diff --git a/lib/std/private/oscommon.nim b/lib/std/private/oscommon.nim
new file mode 100644
index 000000000..c49d52ef2
--- /dev/null
+++ b/lib/std/private/oscommon.nim
@@ -0,0 +1,186 @@
+include system/inclrtl
+
+import std/[oserrors]
+
+when defined(nimPreviewSlimSystem):
+  import std/[syncio, assertions, widestrs]
+
+## .. importdoc:: osdirs.nim, os.nim
+
+const weirdTarget* = defined(nimscript) or defined(js)
+
+
+type
+  ReadDirEffect* = object of ReadIOEffect   ## Effect that denotes a read
+                                            ## operation from the directory
+                                            ## structure.
+  WriteDirEffect* = object of WriteIOEffect ## Effect that denotes a write
+                                            ## operation to
+                                            ## the directory structure.
+
+
+when weirdTarget:
+  discard
+elif defined(windows):
+  import std/[winlean, times]
+elif defined(posix):
+  import std/posix
+  proc c_rename(oldname, newname: cstring): cint {.
+    importc: "rename", header: "<stdio.h>".}
+else:
+  {.error: "OS module not ported to your operating system!".}
+
+
+when weirdTarget:
+  {.pragma: noWeirdTarget, error: "this proc is not available on the NimScript/js target".}
+else:
+  {.pragma: noWeirdTarget.}
+
+
+when defined(nimscript):
+  # for procs already defined in scriptconfig.nim
+  template noNimJs(body): untyped = discard
+elif defined(js):
+  {.pragma: noNimJs, error: "this proc is not available on the js target".}
+else:
+  {.pragma: noNimJs.}
+
+
+when defined(windows) and not weirdTarget:
+  template wrapUnary*(varname, winApiProc, arg: untyped) =
+    var varname = winApiProc(newWideCString(arg))
+
+  template wrapBinary*(varname, winApiProc, arg, arg2: untyped) =
+    var varname = winApiProc(newWideCString(arg), arg2)
+  proc findFirstFile*(a: string, b: var WIN32_FIND_DATA): Handle =
+    result = findFirstFileW(newWideCString(a), b)
+  template findNextFile*(a, b: untyped): untyped = findNextFileW(a, b)
+
+  template getFilename*(f: untyped): untyped =
+    $cast[WideCString](addr(f.cFileName[0]))
+
+  proc skipFindData*(f: WIN32_FIND_DATA): bool {.inline.} =
+    # Note - takes advantage of null delimiter in the cstring
+    const dot = ord('.')
+    result = f.cFileName[0].int == dot and (f.cFileName[1].int == 0 or
+             f.cFileName[1].int == dot and f.cFileName[2].int == 0)
+
+
+type
+  PathComponent* = enum   ## Enumeration specifying a path component.
+    ##
+    ## See also:
+    ## * `walkDirRec iterator`_
+    ## * `FileInfo object`_
+    pcFile,               ## path refers to a file
+    pcLinkToFile,         ## path refers to a symbolic link to a file
+    pcDir,                ## path refers to a directory
+    pcLinkToDir           ## path refers to a symbolic link to a directory
+
+
+when defined(posix) and not weirdTarget:
+  proc getSymlinkFileKind*(path: string):
+      tuple[pc: PathComponent, isSpecial: bool] =
+    # Helper function.
+    var s: Stat
+    assert(path != "")
+    result = (pcLinkToFile, false)
+    if stat(path, s) == 0'i32:
+      if S_ISDIR(s.st_mode):
+        result = (pcLinkToDir, false)
+      elif not S_ISREG(s.st_mode):
+        result = (pcLinkToFile, true)
+
+proc tryMoveFSObject*(source, dest: string, isDir: bool): bool {.noWeirdTarget.} =
+  ## Moves a file (or directory if `isDir` is true) from `source` to `dest`.
+  ##
+  ## Returns false in case of `EXDEV` error or `AccessDeniedError` on Windows (if `isDir` is true).
+  ## In case of other errors `OSError` is raised.
+  ## Returns true in case of success.
+  when defined(windows):
+    let s = newWideCString(source)
+    let d = newWideCString(dest)
+    result = moveFileExW(s, d, MOVEFILE_COPY_ALLOWED or MOVEFILE_REPLACE_EXISTING) != 0'i32
+  else:
+    result = c_rename(source, dest) == 0'i32
+
+  if not result:
+    let err = osLastError()
+    let isAccessDeniedError =
+      when defined(windows):
+        const AccessDeniedError = OSErrorCode(5)
+        isDir and err == AccessDeniedError
+      else:
+        err == EXDEV.OSErrorCode
+    if not isAccessDeniedError:
+      raiseOSError(err, $(source, dest))
+
+when not defined(windows):
+  const maxSymlinkLen* = 1024
+
+proc fileExists*(filename: string): bool {.rtl, extern: "nos$1",
+                                          tags: [ReadDirEffect], noNimJs, sideEffect.} =
+  ## Returns true if `filename` exists and is a regular file or symlink.
+  ##
+  ## Directories, device files, named pipes and sockets return false.
+  ##
+  ## See also:
+  ## * `dirExists proc`_
+  ## * `symlinkExists proc`_
+  when defined(windows):
+    wrapUnary(a, getFileAttributesW, filename)
+    if a != -1'i32:
+      result = (a and FILE_ATTRIBUTE_DIRECTORY) == 0'i32
+  else:
+    var res: Stat
+    return stat(filename, res) >= 0'i32 and S_ISREG(res.st_mode)
+
+
+proc dirExists*(dir: string): bool {.rtl, extern: "nos$1", tags: [ReadDirEffect],
+                                     noNimJs, sideEffect.} =
+  ## Returns true if the directory `dir` exists. If `dir` is a file, false
+  ## is returned. Follows symlinks.
+  ##
+  ## See also:
+  ## * `fileExists proc`_
+  ## * `symlinkExists proc`_
+  when defined(windows):
+    wrapUnary(a, getFileAttributesW, dir)
+    if a != -1'i32:
+      result = (a and FILE_ATTRIBUTE_DIRECTORY) != 0'i32
+  else:
+    var res: Stat
+    result = stat(dir, res) >= 0'i32 and S_ISDIR(res.st_mode)
+
+
+proc symlinkExists*(link: string): bool {.rtl, extern: "nos$1",
+                                          tags: [ReadDirEffect],
+                                          noWeirdTarget, sideEffect.} =
+  ## Returns true if the symlink `link` exists. Will return true
+  ## regardless of whether the link points to a directory or file.
+  ##
+  ## See also:
+  ## * `fileExists proc`_
+  ## * `dirExists proc`_
+  when defined(windows):
+    wrapUnary(a, getFileAttributesW, link)
+    if a != -1'i32:
+      # xxx see: bug #16784 (bug9); checking `IO_REPARSE_TAG_SYMLINK`
+      # may also be needed.
+      result = (a and FILE_ATTRIBUTE_REPARSE_POINT) != 0'i32
+  else:
+    var res: Stat
+    result = lstat(link, res) >= 0'i32 and S_ISLNK(res.st_mode)
+
+when defined(windows) and not weirdTarget:
+  proc openHandle*(path: string, followSymlink=true, writeAccess=false): Handle =
+    var flags = FILE_FLAG_BACKUP_SEMANTICS or FILE_ATTRIBUTE_NORMAL
+    if not followSymlink:
+      flags = flags or FILE_FLAG_OPEN_REPARSE_POINT
+    let access = if writeAccess: GENERIC_WRITE else: 0'i32
+
+    result = createFileW(
+      newWideCString(path), access,
+      FILE_SHARE_DELETE or FILE_SHARE_READ or FILE_SHARE_WRITE,
+      nil, OPEN_EXISTING, flags, 0
+      )
diff --git a/lib/std/private/osdirs.nim b/lib/std/private/osdirs.nim
new file mode 100644
index 000000000..a44cad7d9
--- /dev/null
+++ b/lib/std/private/osdirs.nim
@@ -0,0 +1,570 @@
+## .. importdoc:: osfiles.nim, appdirs.nim, paths.nim
+
+include system/inclrtl
+import std/oserrors
+
+
+import ospaths2, osfiles
+import oscommon
+export dirExists, PathComponent
+
+
+when defined(nimPreviewSlimSystem):
+  import std/[syncio, assertions, widestrs]
+
+
+when weirdTarget:
+  discard
+elif defined(windows):
+  import std/[winlean, times]
+elif defined(posix):
+  import std/[posix, times]
+
+else:
+  {.error: "OS module not ported to your operating system!".}
+
+
+when weirdTarget:
+  {.pragma: noWeirdTarget, error: "this proc is not available on the NimScript/js target".}
+else:
+  {.pragma: noWeirdTarget.}
+
+
+when defined(nimscript):
+  # for procs already defined in scriptconfig.nim
+  template noNimJs(body): untyped = discard
+elif defined(js):
+  {.pragma: noNimJs, error: "this proc is not available on the js target".}
+else:
+  {.pragma: noNimJs.}
+
+# Templates for filtering directories and files
+when defined(windows) and not weirdTarget:
+  template isDir(f: WIN32_FIND_DATA): bool =
+    (f.dwFileAttributes and FILE_ATTRIBUTE_DIRECTORY) != 0'i32
+  template isFile(f: WIN32_FIND_DATA): bool =
+    not isDir(f)
+else:
+  template isDir(f: string): bool {.dirty.} =
+    dirExists(f)
+  template isFile(f: string): bool {.dirty.} =
+    fileExists(f)
+
+template defaultWalkFilter(item): bool =
+  ## Walk filter used to return true on both
+  ## files and directories
+  true
+
+template walkCommon(pattern: string, filter) =
+  ## Common code for getting the files and directories with the
+  ## specified `pattern`
+  when defined(windows):
+    var
+      f: WIN32_FIND_DATA
+      res: int
+    res = findFirstFile(pattern, f)
+    if res != -1:
+      defer: findClose(res)
+      let dotPos = searchExtPos(pattern)
+      while true:
+        if not skipFindData(f) and filter(f):
+          # Windows bug/gotcha: 't*.nim' matches 'tfoo.nims' -.- so we check
+          # that the file extensions have the same length ...
+          let ff = getFilename(f)
+          let idx = ff.len - pattern.len + dotPos
+          if dotPos < 0 or idx >= ff.len or (idx >= 0 and ff[idx] == '.') or
+              (dotPos >= 0 and dotPos+1 < pattern.len and pattern[dotPos+1] == '*'):
+            yield splitFile(pattern).dir / extractFilename(ff)
+        if findNextFile(res, f) == 0'i32:
+          let errCode = getLastError()
+          if errCode == ERROR_NO_MORE_FILES: break
+          else: raiseOSError(errCode.OSErrorCode)
+  else: # here we use glob
+    var
+      f: Glob
+      res: int
+    f.gl_offs = 0
+    f.gl_pathc = 0
+    f.gl_pathv = nil
+    res = glob(pattern, 0, nil, addr(f))
+    defer: globfree(addr(f))
+    if res == 0:
+      for i in 0.. f.gl_pathc - 1:
+        assert(f.gl_pathv[i] != nil)
+        let path = $f.gl_pathv[i]
+        if filter(path):
+          yield path
+
+iterator walkPattern*(pattern: string): string {.tags: [ReadDirEffect], noWeirdTarget.} =
+  ## Iterate over all the files and directories that match the `pattern`.
+  ##
+  ## On POSIX this uses the `glob`:idx: call.
+  ## `pattern` is OS dependent, but at least the `"*.ext"`
+  ## notation is supported.
+  ##
+  ## See also:
+  ## * `walkFiles iterator`_
+  ## * `walkDirs iterator`_
+  ## * `walkDir iterator`_
+  ## * `walkDirRec iterator`_
+  runnableExamples:
+    import std/os
+    import std/sequtils
+    let paths = toSeq(walkPattern("lib/pure/*")) # works on Windows too
+    assert "lib/pure/concurrency".unixToNativePath in paths
+    assert "lib/pure/os.nim".unixToNativePath in paths
+  walkCommon(pattern, defaultWalkFilter)
+
+iterator walkFiles*(pattern: string): string {.tags: [ReadDirEffect], noWeirdTarget.} =
+  ## Iterate over all the files that match the `pattern`.
+  ##
+  ## On POSIX this uses the `glob`:idx: call.
+  ## `pattern` is OS dependent, but at least the `"*.ext"`
+  ## notation is supported.
+  ##
+  ## See also:
+  ## * `walkPattern iterator`_
+  ## * `walkDirs iterator`_
+  ## * `walkDir iterator`_
+  ## * `walkDirRec iterator`_
+  runnableExamples:
+    import std/os
+    import std/sequtils
+    assert "lib/pure/os.nim".unixToNativePath in toSeq(walkFiles("lib/pure/*.nim")) # works on Windows too
+  walkCommon(pattern, isFile)
+
+iterator walkDirs*(pattern: string): string {.tags: [ReadDirEffect], noWeirdTarget.} =
+  ## Iterate over all the directories that match the `pattern`.
+  ##
+  ## On POSIX this uses the `glob`:idx: call.
+  ## `pattern` is OS dependent, but at least the `"*.ext"`
+  ## notation is supported.
+  ##
+  ## See also:
+  ## * `walkPattern iterator`_
+  ## * `walkFiles iterator`_
+  ## * `walkDir iterator`_
+  ## * `walkDirRec iterator`_
+  runnableExamples:
+    import std/os
+    import std/sequtils
+    let paths = toSeq(walkDirs("lib/pure/*")) # works on Windows too
+    assert "lib/pure/concurrency".unixToNativePath in paths
+  walkCommon(pattern, isDir)
+
+proc staticWalkDir(dir: string; relative: bool): seq[
+                  tuple[kind: PathComponent, path: string]] =
+  discard
+
+iterator walkDir*(dir: string; relative = false, checkDir = false,
+                  skipSpecial = false):
+  tuple[kind: PathComponent, path: string] {.tags: [ReadDirEffect].} =
+  ## Walks over the directory `dir` and yields for each directory or file in
+  ## `dir`. The component type and full path for each item are returned.
+  ##
+  ## Walking is not recursive.
+  ## * If `relative` is true (default: false)
+  ##   the resulting path is shortened to be relative to ``dir``,
+  ##   otherwise the full path is returned.
+  ## * If `checkDir` is true, `OSError` is raised when `dir`
+  ##   doesn't exist.
+  ## * If `skipSpecial` is true, then (besides all directories) only *regular*
+  ##   files (**without** special "file" objects like FIFOs, device files,
+  ##   etc) will be yielded on Unix.
+  ##
+  ## **Example:**
+  ##
+  ## This directory structure:
+  ##
+  ##     dirA / dirB / fileB1.txt
+  ##          / dirC
+  ##          / fileA1.txt
+  ##          / fileA2.txt
+  ##
+  ## and this code:
+  runnableExamples("-r:off"):
+    import std/[strutils, sugar]
+    # note: order is not guaranteed
+    # this also works at compile time
+    assert collect(for k in walkDir("dirA"): k.path).join(" ") ==
+                          "dirA/dirB dirA/dirC dirA/fileA2.txt dirA/fileA1.txt"
+  ## See also:
+  ## * `walkPattern iterator`_
+  ## * `walkFiles iterator`_
+  ## * `walkDirs iterator`_
+  ## * `walkDirRec iterator`_
+
+  when nimvm:
+    for k, v in items(staticWalkDir(dir, relative)):
+      yield (k, v)
+  else:
+    when weirdTarget:
+      for k, v in items(staticWalkDir(dir, relative)):
+        yield (k, v)
+    elif defined(windows):
+      var f: WIN32_FIND_DATA
+      var h = findFirstFile(dir / "*", f)
+      if h == -1:
+        if checkDir:
+          raiseOSError(osLastError(), dir)
+      else:
+        defer: findClose(h)
+        while true:
+          var k = pcFile
+          if not skipFindData(f):
+            if (f.dwFileAttributes and FILE_ATTRIBUTE_DIRECTORY) != 0'i32:
+              k = pcDir
+            if (f.dwFileAttributes and FILE_ATTRIBUTE_REPARSE_POINT) != 0'i32:
+              k = succ(k)
+            let xx = if relative: extractFilename(getFilename(f))
+                     else: dir / extractFilename(getFilename(f))
+            yield (k, xx)
+          if findNextFile(h, f) == 0'i32:
+            let errCode = getLastError()
+            if errCode == ERROR_NO_MORE_FILES: break
+            else: raiseOSError(errCode.OSErrorCode)
+    else:
+      var d = opendir(dir)
+      if d == nil:
+        if checkDir:
+          raiseOSError(osLastError(), dir)
+      else:
+        defer: discard closedir(d)
+        while true:
+          var x = readdir(d)
+          if x == nil: break
+          var y = $cast[cstring](addr x.d_name)
+          if y != "." and y != "..":
+            var s: Stat
+            let path = dir / y
+            if not relative:
+              y = path
+            var k = pcFile
+
+            template resolveSymlink() =
+              var isSpecial: bool
+              (k, isSpecial) = getSymlinkFileKind(path)
+              if skipSpecial and isSpecial: continue
+
+            template kSetGeneric() =  # pure Posix component `k` resolution
+              if lstat(path.cstring, s) < 0'i32: continue  # don't yield
+              elif S_ISDIR(s.st_mode):
+                k = pcDir
+              elif S_ISLNK(s.st_mode):
+                resolveSymlink()
+              elif skipSpecial and not S_ISREG(s.st_mode): continue
+
+            when defined(linux) or defined(macosx) or
+                 defined(bsd) or defined(genode) or defined(nintendoswitch):
+              case x.d_type
+              of DT_DIR: k = pcDir
+              of DT_LNK:
+                resolveSymlink()
+              of DT_UNKNOWN:
+                kSetGeneric()
+              else: # DT_REG or special "files" like FIFOs
+                if skipSpecial and x.d_type != DT_REG: continue
+                else: discard # leave it as pcFile
+            else:  # assuming that field `d_type` is not present
+              kSetGeneric()
+
+            yield (k, y)
+
+iterator walkDirRec*(dir: string,
+                     yieldFilter = {pcFile}, followFilter = {pcDir},
+                     relative = false, checkDir = false, skipSpecial = false):
+                    string {.tags: [ReadDirEffect].} =
+  ## Recursively walks over the directory `dir` and yields for each file
+  ## or directory in `dir`.
+  ##
+  ## Options `relative`, `checkdir`, `skipSpecial` are explained in
+  ## [walkDir iterator] description.
+  ##
+  ## .. warning:: Modifying the directory structure while the iterator
+  ##   is traversing may result in undefined behavior!
+  ##
+  ## Walking is recursive. `followFilter` controls the behaviour of the iterator:
+  ##
+  ## =====================   =============================================
+  ## yieldFilter             meaning
+  ## =====================   =============================================
+  ## ``pcFile``              yield real files (default)
+  ## ``pcLinkToFile``        yield symbolic links to files
+  ## ``pcDir``               yield real directories
+  ## ``pcLinkToDir``         yield symbolic links to directories
+  ## =====================   =============================================
+  ##
+  ## =====================   =============================================
+  ## followFilter            meaning
+  ## =====================   =============================================
+  ## ``pcDir``               follow real directories (default)
+  ## ``pcLinkToDir``         follow symbolic links to directories
+  ## =====================   =============================================
+  ##
+  ##
+  ## See also:
+  ## * `walkPattern iterator`_
+  ## * `walkFiles iterator`_
+  ## * `walkDirs iterator`_
+  ## * `walkDir iterator`_
+
+  var stack = @[""]
+  var checkDir = checkDir
+  while stack.len > 0:
+    let d = stack.pop()
+    for k, p in walkDir(dir / d, relative = true, checkDir = checkDir,
+                        skipSpecial = skipSpecial):
+      let rel = d / p
+      if k in {pcDir, pcLinkToDir} and k in followFilter:
+        stack.add rel
+      if k in yieldFilter:
+        yield if relative: rel else: dir / rel
+    checkDir = false
+      # We only check top-level dir, otherwise if a subdir is invalid (eg. wrong
+      # permissions), it'll abort iteration and there would be no way to
+      # continue iteration.
+      # Future work can provide a way to customize this and do error reporting.
+
+
+proc rawRemoveDir(dir: string) {.noWeirdTarget.} =
+  when defined(windows):
+    wrapUnary(res, removeDirectoryW, dir)
+    let lastError = osLastError()
+    if res == 0'i32 and lastError.int32 != 3'i32 and
+        lastError.int32 != 18'i32 and lastError.int32 != 2'i32:
+      raiseOSError(lastError, dir)
+  else:
+    if rmdir(dir) != 0'i32 and errno != ENOENT: raiseOSError(osLastError(), dir)
+
+proc removeDir*(dir: string, checkDir = false) {.rtl, extern: "nos$1", tags: [
+  WriteDirEffect, ReadDirEffect], benign, noWeirdTarget.} =
+  ## Removes the directory `dir` including all subdirectories and files
+  ## in `dir` (recursively).
+  ##
+  ## If this fails, `OSError` is raised. This does not fail if the directory never
+  ## existed in the first place, unless `checkDir` = true.
+  ##
+  ## See also:
+  ## * `tryRemoveFile proc`_
+  ## * `removeFile proc`_
+  ## * `existsOrCreateDir proc`_
+  ## * `createDir proc`_
+  ## * `copyDir proc`_
+  ## * `copyDirWithPermissions proc`_
+  ## * `moveDir proc`_
+  for kind, path in walkDir(dir, checkDir = checkDir):
+    case kind
+    of pcFile, pcLinkToFile, pcLinkToDir: removeFile(path)
+    of pcDir: removeDir(path, true)
+      # for subdirectories there is no benefit in `checkDir = false`
+      # (unless perhaps for edge case of concurrent processes also deleting
+      # the same files)
+  rawRemoveDir(dir)
+
+proc rawCreateDir(dir: string): bool {.noWeirdTarget.} =
+  # Try to create one directory (not the whole path).
+  # returns `true` for success, `false` if the path has previously existed
+  #
+  # This is a thin wrapper over mkDir (or alternatives on other systems),
+  # so in case of a pre-existing path we don't check that it is a directory.
+  when defined(solaris):
+    let res = mkdir(dir, 0o777)
+    if res == 0'i32:
+      result = true
+    elif errno in {EEXIST, ENOSYS}:
+      result = false
+    else:
+      raiseOSError(osLastError(), dir)
+  elif defined(haiku):
+    let res = mkdir(dir, 0o777)
+    if res == 0'i32:
+      result = true
+    elif errno == EEXIST or errno == EROFS:
+      result = false
+    else:
+      raiseOSError(osLastError(), dir)
+  elif defined(posix):
+    let res = mkdir(dir, 0o777)
+    if res == 0'i32:
+      result = true
+    elif errno == EEXIST:
+      result = false
+    else:
+      #echo res
+      raiseOSError(osLastError(), dir)
+  else:
+    wrapUnary(res, createDirectoryW, dir)
+
+    if res != 0'i32:
+      result = true
+    elif getLastError() == 183'i32:
+      result = false
+    else:
+      raiseOSError(osLastError(), dir)
+
+proc existsOrCreateDir*(dir: string): bool {.rtl, extern: "nos$1",
+  tags: [WriteDirEffect, ReadDirEffect], noWeirdTarget.} =
+  ## Checks if a `directory`:idx: `dir` exists, and creates it otherwise.
+  ##
+  ## Does not create parent directories (raises `OSError` if parent directories do not exist).
+  ## Returns `true` if the directory already exists, and `false` otherwise.
+  ##
+  ## See also:
+  ## * `removeDir proc`_
+  ## * `createDir proc`_
+  ## * `copyDir proc`_
+  ## * `copyDirWithPermissions proc`_
+  ## * `moveDir proc`_
+  result = not rawCreateDir(dir)
+  if result:
+    # path already exists - need to check that it is indeed a directory
+    if not dirExists(dir):
+      raise newException(IOError, "Failed to create '" & dir & "'")
+
+proc createDir*(dir: string) {.rtl, extern: "nos$1",
+  tags: [WriteDirEffect, ReadDirEffect], noWeirdTarget.} =
+  ## Creates the `directory`:idx: `dir`.
+  ##
+  ## The directory may contain several subdirectories that do not exist yet.
+  ## The full path is created. If this fails, `OSError` is raised.
+  ##
+  ## It does **not** fail if the directory already exists because for
+  ## most usages this does not indicate an error.
+  ##
+  ## See also:
+  ## * `removeDir proc`_
+  ## * `existsOrCreateDir proc`_
+  ## * `copyDir proc`_
+  ## * `copyDirWithPermissions proc`_
+  ## * `moveDir proc`_
+  if dir == "":
+    return
+  var omitNext = isAbsolute(dir)
+  for p in parentDirs(dir, fromRoot=true):
+    if omitNext:
+      omitNext = false
+    else:
+      discard existsOrCreateDir(p)
+
+proc copyDir*(source, dest: string, skipSpecial = false) {.rtl, extern: "nos$1",
+  tags: [ReadDirEffect, WriteIOEffect, ReadIOEffect], benign, noWeirdTarget.} =
+  ## Copies a directory from `source` to `dest`.
+  ##
+  ## On non-Windows OSes, symlinks are copied as symlinks. On Windows, symlinks
+  ## are skipped.
+  ##
+  ## If `skipSpecial` is true, then (besides all directories) only *regular*
+  ## files (**without** special "file" objects like FIFOs, device files,
+  ## etc) will be copied on Unix.
+  ##
+  ## If this fails, `OSError` is raised.
+  ##
+  ## On the Windows platform this proc will copy the attributes from
+  ## `source` into `dest`.
+  ##
+  ## On other platforms created files and directories will inherit the
+  ## default permissions of a newly created file/directory for the user.
+  ## Use `copyDirWithPermissions proc`_
+  ## to preserve attributes recursively on these platforms.
+  ##
+  ## See also:
+  ## * `copyDirWithPermissions proc`_
+  ## * `copyFile proc`_
+  ## * `copyFileWithPermissions proc`_
+  ## * `removeDir proc`_
+  ## * `existsOrCreateDir proc`_
+  ## * `createDir proc`_
+  ## * `moveDir proc`_
+  createDir(dest)
+  for kind, path in walkDir(source, skipSpecial = skipSpecial):
+    var noSource = splitPath(path).tail
+    if kind == pcDir:
+      copyDir(path, dest / noSource, skipSpecial = skipSpecial)
+    else:
+      copyFile(path, dest / noSource, {cfSymlinkAsIs})
+
+
+proc copyDirWithPermissions*(source, dest: string,
+                             ignorePermissionErrors = true,
+                             skipSpecial = false)
+  {.rtl, extern: "nos$1", tags: [ReadDirEffect, WriteIOEffect, ReadIOEffect],
+   benign, noWeirdTarget.} =
+  ## Copies a directory from `source` to `dest` preserving file permissions.
+  ##
+  ## On non-Windows OSes, symlinks are copied as symlinks. On Windows, symlinks
+  ## are skipped.
+  ##
+  ## If `skipSpecial` is true, then (besides all directories) only *regular*
+  ## files (**without** special "file" objects like FIFOs, device files,
+  ## etc) will be copied on Unix.
+  ##
+  ## If this fails, `OSError` is raised. This is a wrapper proc around
+  ## `copyDir`_ and `copyFileWithPermissions`_ procs
+  ## on non-Windows platforms.
+  ##
+  ## On Windows this proc is just a wrapper for `copyDir proc`_ since
+  ## that proc already copies attributes.
+  ##
+  ## On non-Windows systems permissions are copied after the file or directory
+  ## itself has been copied, which won't happen atomically and could lead to a
+  ## race condition. If `ignorePermissionErrors` is true (default), errors while
+  ## reading/setting file attributes will be ignored, otherwise will raise
+  ## `OSError`.
+  ##
+  ## See also:
+  ## * `copyDir proc`_
+  ## * `copyFile proc`_
+  ## * `copyFileWithPermissions proc`_
+  ## * `removeDir proc`_
+  ## * `moveDir proc`_
+  ## * `existsOrCreateDir proc`_
+  ## * `createDir proc`_
+  createDir(dest)
+  when not defined(windows):
+    try:
+      setFilePermissions(dest, getFilePermissions(source), followSymlinks =
+                         false)
+    except:
+      if not ignorePermissionErrors:
+        raise
+  for kind, path in walkDir(source, skipSpecial = skipSpecial):
+    var noSource = splitPath(path).tail
+    if kind == pcDir:
+      copyDirWithPermissions(path, dest / noSource, ignorePermissionErrors, skipSpecial = skipSpecial)
+    else:
+      copyFileWithPermissions(path, dest / noSource, ignorePermissionErrors, {cfSymlinkAsIs})
+
+proc moveDir*(source, dest: string) {.tags: [ReadIOEffect, WriteIOEffect], noWeirdTarget.} =
+  ## Moves a directory from `source` to `dest`.
+  ##
+  ## Symlinks are not followed: if `source` contains symlinks, they themself are
+  ## moved, not their target.
+  ##
+  ## If this fails, `OSError` is raised.
+  ##
+  ## See also:
+  ## * `moveFile proc`_
+  ## * `copyDir proc`_
+  ## * `copyDirWithPermissions proc`_
+  ## * `removeDir proc`_
+  ## * `existsOrCreateDir proc`_
+  ## * `createDir proc`_
+  if not tryMoveFSObject(source, dest, isDir = true):
+    # Fallback to copy & del
+    copyDir(source, dest)
+    removeDir(source)
+
+proc setCurrentDir*(newDir: string) {.inline, tags: [], noWeirdTarget.} =
+  ## Sets the `current working directory`:idx:; `OSError`
+  ## is raised if `newDir` cannot been set.
+  ##
+  ## See also:
+  ## * `getHomeDir proc`_
+  ## * `getConfigDir proc`_
+  ## * `getTempDir proc`_
+  ## * `getCurrentDir proc`_
+  when defined(windows):
+    if setCurrentDirectoryW(newWideCString(newDir)) == 0'i32:
+      raiseOSError(osLastError(), newDir)
+  else:
+    if chdir(newDir) != 0'i32: raiseOSError(osLastError(), newDir)
diff --git a/lib/std/private/osfiles.nim b/lib/std/private/osfiles.nim
new file mode 100644
index 000000000..37d8eabca
--- /dev/null
+++ b/lib/std/private/osfiles.nim
@@ -0,0 +1,416 @@
+include system/inclrtl
+import std/private/since
+import std/oserrors
+
+import oscommon
+export fileExists
+
+import ospaths2, ossymlinks
+
+## .. importdoc:: osdirs.nim, os.nim
+
+when defined(nimPreviewSlimSystem):
+  import std/[syncio, assertions, widestrs]
+
+when weirdTarget:
+  discard
+elif defined(windows):
+  import std/winlean
+elif defined(posix):
+  import std/[posix, times]
+
+  proc toTime(ts: Timespec): times.Time {.inline.} =
+    result = initTime(ts.tv_sec.int64, ts.tv_nsec.int)
+else:
+  {.error: "OS module not ported to your operating system!".}
+
+
+when weirdTarget:
+  {.pragma: noWeirdTarget, error: "this proc is not available on the NimScript/js target".}
+else:
+  {.pragma: noWeirdTarget.}
+
+
+when defined(nimscript):
+  # for procs already defined in scriptconfig.nim
+  template noNimJs(body): untyped = discard
+elif defined(js):
+  {.pragma: noNimJs, error: "this proc is not available on the js target".}
+else:
+  {.pragma: noNimJs.}
+
+
+type
+  FilePermission* = enum   ## File access permission, modelled after UNIX.
+    ##
+    ## See also:
+    ## * `getFilePermissions`_
+    ## * `setFilePermissions`_
+    ## * `FileInfo object`_
+    fpUserExec,            ## execute access for the file owner
+    fpUserWrite,           ## write access for the file owner
+    fpUserRead,            ## read access for the file owner
+    fpGroupExec,           ## execute access for the group
+    fpGroupWrite,          ## write access for the group
+    fpGroupRead,           ## read access for the group
+    fpOthersExec,          ## execute access for others
+    fpOthersWrite,         ## write access for others
+    fpOthersRead           ## read access for others
+
+proc getFilePermissions*(filename: string): set[FilePermission] {.
+  rtl, extern: "nos$1", tags: [ReadDirEffect], noWeirdTarget.} =
+  ## Retrieves file permissions for `filename`.
+  ##
+  ## `OSError` is raised in case of an error.
+  ## On Windows, only the ``readonly`` flag is checked, every other
+  ## permission is available in any case.
+  ##
+  ## See also:
+  ## * `setFilePermissions proc`_
+  ## * `FilePermission enum`_
+  when defined(posix):
+    var a: Stat
+    if stat(filename, a) < 0'i32: raiseOSError(osLastError(), filename)
+    result = {}
+    if (a.st_mode and S_IRUSR.Mode) != 0.Mode: result.incl(fpUserRead)
+    if (a.st_mode and S_IWUSR.Mode) != 0.Mode: result.incl(fpUserWrite)
+    if (a.st_mode and S_IXUSR.Mode) != 0.Mode: result.incl(fpUserExec)
+
+    if (a.st_mode and S_IRGRP.Mode) != 0.Mode: result.incl(fpGroupRead)
+    if (a.st_mode and S_IWGRP.Mode) != 0.Mode: result.incl(fpGroupWrite)
+    if (a.st_mode and S_IXGRP.Mode) != 0.Mode: result.incl(fpGroupExec)
+
+    if (a.st_mode and S_IROTH.Mode) != 0.Mode: result.incl(fpOthersRead)
+    if (a.st_mode and S_IWOTH.Mode) != 0.Mode: result.incl(fpOthersWrite)
+    if (a.st_mode and S_IXOTH.Mode) != 0.Mode: result.incl(fpOthersExec)
+  else:
+    wrapUnary(res, getFileAttributesW, filename)
+    if res == -1'i32: raiseOSError(osLastError(), filename)
+    if (res and FILE_ATTRIBUTE_READONLY) != 0'i32:
+      result = {fpUserExec, fpUserRead, fpGroupExec, fpGroupRead,
+                fpOthersExec, fpOthersRead}
+    else:
+      result = {fpUserExec..fpOthersRead}
+
+proc setFilePermissions*(filename: string, permissions: set[FilePermission],
+                         followSymlinks = true)
+  {.rtl, extern: "nos$1", tags: [ReadDirEffect, WriteDirEffect],
+   noWeirdTarget.} =
+  ## Sets the file permissions for `filename`.
+  ##
+  ## If `followSymlinks` set to true (default) and ``filename`` points to a
+  ## symlink, permissions are set to the file symlink points to.
+  ## `followSymlinks` set to false is a noop on Windows and some POSIX
+  ## systems (including Linux) on which `lchmod` is either unavailable or always
+  ## fails, given that symlinks permissions there are not observed.
+  ##
+  ## `OSError` is raised in case of an error.
+  ## On Windows, only the ``readonly`` flag is changed, depending on
+  ## ``fpUserWrite`` permission.
+  ##
+  ## See also:
+  ## * `getFilePermissions proc`_
+  ## * `FilePermission enum`_
+  when defined(posix):
+    var p = 0.Mode
+    if fpUserRead in permissions: p = p or S_IRUSR.Mode
+    if fpUserWrite in permissions: p = p or S_IWUSR.Mode
+    if fpUserExec in permissions: p = p or S_IXUSR.Mode
+
+    if fpGroupRead in permissions: p = p or S_IRGRP.Mode
+    if fpGroupWrite in permissions: p = p or S_IWGRP.Mode
+    if fpGroupExec in permissions: p = p or S_IXGRP.Mode
+
+    if fpOthersRead in permissions: p = p or S_IROTH.Mode
+    if fpOthersWrite in permissions: p = p or S_IWOTH.Mode
+    if fpOthersExec in permissions: p = p or S_IXOTH.Mode
+
+    if not followSymlinks and filename.symlinkExists:
+      when declared(lchmod):
+        if lchmod(filename, cast[Mode](p)) != 0:
+          raiseOSError(osLastError(), $(filename, permissions))
+    else:
+      if chmod(filename, cast[Mode](p)) != 0:
+        raiseOSError(osLastError(), $(filename, permissions))
+  else:
+    wrapUnary(res, getFileAttributesW, filename)
+    if res == -1'i32: raiseOSError(osLastError(), filename)
+    if fpUserWrite in permissions:
+      res = res and not FILE_ATTRIBUTE_READONLY
+    else:
+      res = res or FILE_ATTRIBUTE_READONLY
+    wrapBinary(res2, setFileAttributesW, filename, res)
+    if res2 == - 1'i32: raiseOSError(osLastError(), $(filename, permissions))
+
+
+const hasCCopyfile = defined(osx) and not defined(nimLegacyCopyFile)
+  # xxx instead of `nimLegacyCopyFile`, support something like: `when osxVersion >= (10, 5)`
+
+when hasCCopyfile:
+  # `copyfile` API available since osx 10.5.
+  {.push nodecl, header: "<copyfile.h>".}
+  type
+    copyfile_state_t {.nodecl.} = pointer
+    copyfile_flags_t = cint
+  proc copyfile_state_alloc(): copyfile_state_t
+  proc copyfile_state_free(state: copyfile_state_t): cint
+  proc c_copyfile(src, dst: cstring,  state: copyfile_state_t, flags: copyfile_flags_t): cint {.importc: "copyfile".}
+  when (NimMajor, NimMinor) >= (1, 4):
+    let
+      COPYFILE_DATA {.nodecl.}: copyfile_flags_t
+      COPYFILE_XATTR {.nodecl.}: copyfile_flags_t
+  else:
+    var
+      COPYFILE_DATA {.nodecl.}: copyfile_flags_t
+      COPYFILE_XATTR {.nodecl.}: copyfile_flags_t
+  {.pop.}
+
+type
+  CopyFlag* = enum    ## Copy options.
+    cfSymlinkAsIs,    ## Copy symlinks as symlinks
+    cfSymlinkFollow,  ## Copy the files symlinks point to
+    cfSymlinkIgnore   ## Ignore symlinks
+
+const copyFlagSymlink = {cfSymlinkAsIs, cfSymlinkFollow, cfSymlinkIgnore}
+
+proc copyFile*(source, dest: string, options = {cfSymlinkFollow}; bufferSize = 16_384) {.rtl,
+  extern: "nos$1", tags: [ReadDirEffect, ReadIOEffect, WriteIOEffect],
+  noWeirdTarget.} =
+  ## Copies a file from `source` to `dest`, where `dest.parentDir` must exist.
+  ##
+  ## On non-Windows OSes, `options` specify the way file is copied; by default,
+  ## if `source` is a symlink, copies the file symlink points to. `options` is
+  ## ignored on Windows: symlinks are skipped.
+  ##
+  ## If this fails, `OSError` is raised.
+  ##
+  ## On the Windows platform this proc will
+  ## copy the source file's attributes into dest.
+  ##
+  ## On other platforms you need
+  ## to use `getFilePermissions`_ and
+  ## `setFilePermissions`_
+  ## procs
+  ## to copy them by hand (or use the convenience `copyFileWithPermissions
+  ## proc`_),
+  ## otherwise `dest` will inherit the default permissions of a newly
+  ## created file for the user.
+  ##
+  ## If `dest` already exists, the file attributes
+  ## will be preserved and the content overwritten.
+  ##
+  ## On OSX, `copyfile` C api will be used (available since OSX 10.5) unless
+  ## `-d:nimLegacyCopyFile` is used.
+  ##
+  ## `copyFile` allows to specify `bufferSize` to improve I/O performance.
+  ##
+  ## See also:
+  ## * `CopyFlag enum`_
+  ## * `copyDir proc`_
+  ## * `copyFileWithPermissions proc`_
+  ## * `tryRemoveFile proc`_
+  ## * `removeFile proc`_
+  ## * `moveFile proc`_
+
+  doAssert card(copyFlagSymlink * options) == 1, "There should be exactly one cfSymlink* in options"
+  let isSymlink = source.symlinkExists
+  if isSymlink and (cfSymlinkIgnore in options or defined(windows)):
+    return
+  when defined(windows):
+    let s = newWideCString(source)
+    let d = newWideCString(dest)
+    if copyFileW(s, d, 0'i32) == 0'i32:
+      raiseOSError(osLastError(), $(source, dest))
+  else:
+    if isSymlink and cfSymlinkAsIs in options:
+      createSymlink(expandSymlink(source), dest)
+    else:
+      when hasCCopyfile:
+        let state = copyfile_state_alloc()
+        # xxx `COPYFILE_STAT` could be used for one-shot
+        # `copyFileWithPermissions`.
+        let status = c_copyfile(source.cstring, dest.cstring, state,
+                                COPYFILE_DATA)
+        if status != 0:
+          let err = osLastError()
+          discard copyfile_state_free(state)
+          raiseOSError(err, $(source, dest))
+        let status2 = copyfile_state_free(state)
+        if status2 != 0: raiseOSError(osLastError(), $(source, dest))
+      else:
+        # generic version of copyFile which works for any platform:
+        var d, s: File
+        if not open(s, source): raiseOSError(osLastError(), source)
+        if not open(d, dest, fmWrite):
+          close(s)
+          raiseOSError(osLastError(), dest)
+
+        # Hints for kernel-level aggressive sequential low-fragmentation read-aheads:
+        # https://pubs.opengroup.org/onlinepubs/9699919799/functions/posix_fadvise.html
+        when defined(linux) or defined(osx):
+          discard posix_fadvise(getFileHandle(d), 0.cint, 0.cint, POSIX_FADV_SEQUENTIAL)
+          discard posix_fadvise(getFileHandle(s), 0.cint, 0.cint, POSIX_FADV_SEQUENTIAL)
+
+        var buf = alloc(bufferSize)
+        while true:
+          var bytesread = readBuffer(s, buf, bufferSize)
+          if bytesread > 0:
+            var byteswritten = writeBuffer(d, buf, bytesread)
+            if bytesread != byteswritten:
+              dealloc(buf)
+              close(s)
+              close(d)
+              raiseOSError(osLastError(), dest)
+          if bytesread != bufferSize: break
+        dealloc(buf)
+        close(s)
+        flushFile(d)
+        close(d)
+
+proc copyFileToDir*(source, dir: string, options = {cfSymlinkFollow}; bufferSize = 16_384)
+  {.noWeirdTarget, since: (1,3,7).} =
+  ## Copies a file `source` into directory `dir`, which must exist.
+  ##
+  ## On non-Windows OSes, `options` specify the way file is copied; by default,
+  ## if `source` is a symlink, copies the file symlink points to. `options` is
+  ## ignored on Windows: symlinks are skipped.
+  ##
+  ## `copyFileToDir` allows to specify `bufferSize` to improve I/O performance.
+  ##
+  ## See also:
+  ## * `CopyFlag enum`_
+  ## * `copyFile proc`_
+  if dir.len == 0: # treating "" as "." is error prone
+    raise newException(ValueError, "dest is empty")
+  copyFile(source, dir / source.lastPathPart, options, bufferSize)
+
+
+proc copyFileWithPermissions*(source, dest: string,
+                              ignorePermissionErrors = true,
+                              options = {cfSymlinkFollow}) {.noWeirdTarget.} =
+  ## Copies a file from `source` to `dest` preserving file permissions.
+  ##
+  ## On non-Windows OSes, `options` specify the way file is copied; by default,
+  ## if `source` is a symlink, copies the file symlink points to. `options` is
+  ## ignored on Windows: symlinks are skipped.
+  ##
+  ## This is a wrapper proc around `copyFile`_,
+  ## `getFilePermissions`_ and `setFilePermissions`_
+  ## procs on non-Windows platforms.
+  ##
+  ## On Windows this proc is just a wrapper for `copyFile proc`_ since
+  ## that proc already copies attributes.
+  ##
+  ## On non-Windows systems permissions are copied after the file itself has
+  ## been copied, which won't happen atomically and could lead to a race
+  ## condition. If `ignorePermissionErrors` is true (default), errors while
+  ## reading/setting file attributes will be ignored, otherwise will raise
+  ## `OSError`.
+  ##
+  ## See also:
+  ## * `CopyFlag enum`_
+  ## * `copyFile proc`_
+  ## * `copyDir proc`_
+  ## * `tryRemoveFile proc`_
+  ## * `removeFile proc`_
+  ## * `moveFile proc`_
+  ## * `copyDirWithPermissions proc`_
+  copyFile(source, dest, options)
+  when not defined(windows):
+    try:
+      setFilePermissions(dest, getFilePermissions(source), followSymlinks =
+                         (cfSymlinkFollow in options))
+    except:
+      if not ignorePermissionErrors:
+        raise
+
+when not declared(ENOENT) and not defined(windows):
+  when defined(nimscript):
+    when not defined(haiku):
+      const ENOENT = cint(2) # 2 on most systems including Solaris
+    else:
+      const ENOENT = cint(-2147459069)
+  else:
+    var ENOENT {.importc, header: "<errno.h>".}: cint
+
+when defined(windows) and not weirdTarget:
+  template deleteFile(file: untyped): untyped  = deleteFileW(file)
+  template setFileAttributes(file, attrs: untyped): untyped =
+    setFileAttributesW(file, attrs)
+
+proc tryRemoveFile*(file: string): bool {.rtl, extern: "nos$1", tags: [WriteDirEffect], noWeirdTarget.} =
+  ## Removes the `file`.
+  ##
+  ## If this fails, returns `false`. This does not fail
+  ## if the file never existed in the first place.
+  ##
+  ## On Windows, ignores the read-only attribute.
+  ##
+  ## See also:
+  ## * `copyFile proc`_
+  ## * `copyFileWithPermissions proc`_
+  ## * `removeFile proc`_
+  ## * `moveFile proc`_
+  result = true
+  when defined(windows):
+    let f = newWideCString(file)
+    if deleteFile(f) == 0:
+      result = false
+      let err = getLastError()
+      if err == ERROR_FILE_NOT_FOUND or err == ERROR_PATH_NOT_FOUND:
+        result = true
+      elif err == ERROR_ACCESS_DENIED and
+         setFileAttributes(f, FILE_ATTRIBUTE_NORMAL) != 0 and
+         deleteFile(f) != 0:
+        result = true
+  else:
+    if unlink(file) != 0'i32 and errno != ENOENT:
+      result = false
+
+proc removeFile*(file: string) {.rtl, extern: "nos$1", tags: [WriteDirEffect], noWeirdTarget.} =
+  ## Removes the `file`.
+  ##
+  ## If this fails, `OSError` is raised. This does not fail
+  ## if the file never existed in the first place.
+  ##
+  ## On Windows, ignores the read-only attribute.
+  ##
+  ## See also:
+  ## * `removeDir proc`_
+  ## * `copyFile proc`_
+  ## * `copyFileWithPermissions proc`_
+  ## * `tryRemoveFile proc`_
+  ## * `moveFile proc`_
+  if not tryRemoveFile(file):
+    raiseOSError(osLastError(), file)
+
+proc moveFile*(source, dest: string) {.rtl, extern: "nos$1",
+  tags: [ReadDirEffect, ReadIOEffect, WriteIOEffect], noWeirdTarget.} =
+  ## Moves a file from `source` to `dest`.
+  ##
+  ## Symlinks are not followed: if `source` is a symlink, it is itself moved,
+  ## not its target.
+  ##
+  ## If this fails, `OSError` is raised.
+  ## If `dest` already exists, it will be overwritten.
+  ##
+  ## Can be used to `rename files`:idx:.
+  ##
+  ## See also:
+  ## * `moveDir proc`_
+  ## * `copyFile proc`_
+  ## * `copyFileWithPermissions proc`_
+  ## * `removeFile proc`_
+  ## * `tryRemoveFile proc`_
+
+  if not tryMoveFSObject(source, dest, isDir = false):
+    when defined(windows):
+      raiseAssert "unreachable"
+    else:
+      # Fallback to copy & del
+      copyFileWithPermissions(source, dest, options={cfSymlinkAsIs})
+      try:
+        removeFile(source)
+      except:
+        discard tryRemoveFile(dest)
+        raise
diff --git a/lib/std/private/ospaths2.nim b/lib/std/private/ospaths2.nim
new file mode 100644
index 000000000..bc69ff725
--- /dev/null
+++ b/lib/std/private/ospaths2.nim
@@ -0,0 +1,1030 @@
+include system/inclrtl
+import std/private/since
+
+import std/[strutils, pathnorm]
+import std/oserrors
+
+import oscommon
+export ReadDirEffect, WriteDirEffect
+
+when defined(nimPreviewSlimSystem):
+  import std/[syncio, assertions, widestrs]
+
+## .. importdoc:: osappdirs.nim, osdirs.nim, osseps.nim, os.nim
+
+const weirdTarget = defined(nimscript) or defined(js)
+
+when weirdTarget:
+  discard
+elif defined(windows):
+  import std/winlean
+elif defined(posix):
+  import std/posix, system/ansi_c
+else:
+  {.error: "OS module not ported to your operating system!".}
+
+when weirdTarget:
+  {.pragma: noWeirdTarget, error: "this proc is not available on the NimScript/js target".}
+else:
+  {.pragma: noWeirdTarget.}
+
+when defined(nimscript):
+  # for procs already defined in scriptconfig.nim
+  template noNimJs(body): untyped = discard
+elif defined(js):
+  {.pragma: noNimJs, error: "this proc is not available on the js target".}
+else:
+  {.pragma: noNimJs.}
+
+
+proc normalizePathAux(path: var string){.inline, raises: [], noSideEffect.}
+
+
+import std/private/osseps
+export osseps
+
+proc absolutePathInternal(path: string): string {.gcsafe.}
+
+proc normalizePathEnd*(path: var string, trailingSep = false) =
+  ## Ensures ``path`` has exactly 0 or 1 trailing `DirSep`, depending on
+  ## ``trailingSep``, and taking care of edge cases: it preservers whether
+  ## a path is absolute or relative, and makes sure trailing sep is `DirSep`,
+  ## not `AltSep`. Trailing `/.` are compressed, see examples.
+  if path.len == 0: return
+  var i = path.len
+  while i >= 1:
+    if path[i-1] in {DirSep, AltSep}: dec(i)
+    elif path[i-1] == '.' and i >= 2 and path[i-2] in {DirSep, AltSep}: dec(i)
+    else: break
+  if trailingSep:
+    # foo// => foo
+    path.setLen(i)
+    # foo => foo/
+    path.add DirSep
+  elif i > 0:
+    # foo// => foo
+    path.setLen(i)
+  else:
+    # // => / (empty case was already taken care of)
+    path = $DirSep
+
+proc normalizePathEnd*(path: string, trailingSep = false): string =
+  ## outplace overload
+  runnableExamples:
+    when defined(posix):
+      assert normalizePathEnd("/lib//.//", trailingSep = true) == "/lib/"
+      assert normalizePathEnd("lib/./.", trailingSep = false) == "lib"
+      assert normalizePathEnd(".//./.", trailingSep = false) == "."
+      assert normalizePathEnd("", trailingSep = true) == "" # not / !
+      assert normalizePathEnd("/", trailingSep = false) == "/" # not "" !
+  result = path
+  result.normalizePathEnd(trailingSep)
+
+template endsWith(a: string, b: set[char]): bool =
+  a.len > 0 and a[^1] in b
+
+proc joinPathImpl(result: var string, state: var int, tail: string) =
+  let trailingSep = tail.endsWith({DirSep, AltSep}) or tail.len == 0 and result.endsWith({DirSep, AltSep})
+  normalizePathEnd(result, trailingSep=false)
+  addNormalizePath(tail, result, state, DirSep)
+  normalizePathEnd(result, trailingSep=trailingSep)
+
+proc joinPath*(head, tail: string): string {.
+  noSideEffect, rtl, extern: "nos$1".} =
+  ## Joins two directory names to one.
+  ##
+  ## returns normalized path concatenation of `head` and `tail`, preserving
+  ## whether or not `tail` has a trailing slash (or, if tail if empty, whether
+  ## head has one).
+  ##
+  ## See also:
+  ## * `joinPath(parts: varargs[string]) proc`_
+  ## * `/ proc`_
+  ## * `splitPath proc`_
+  ## * `uri.combine proc <uri.html#combine,Uri,Uri>`_
+  ## * `uri./ proc <uri.html#/,Uri,string>`_
+  runnableExamples:
+    when defined(posix):
+      assert joinPath("usr", "lib") == "usr/lib"
+      assert joinPath("usr", "lib/") == "usr/lib/"
+      assert joinPath("usr", "") == "usr"
+      assert joinPath("usr/", "") == "usr/"
+      assert joinPath("", "") == ""
+      assert joinPath("", "lib") == "lib"
+      assert joinPath("", "/lib") == "/lib"
+      assert joinPath("usr/", "/lib") == "usr/lib"
+      assert joinPath("usr/lib", "../bin") == "usr/bin"
+
+  result = newStringOfCap(head.len + tail.len)
+  var state = 0
+  joinPathImpl(result, state, head)
+  joinPathImpl(result, state, tail)
+  when false:
+    if len(head) == 0:
+      result = tail
+    elif head[len(head)-1] in {DirSep, AltSep}:
+      if tail.len > 0 and tail[0] in {DirSep, AltSep}:
+        result = head & substr(tail, 1)
+      else:
+        result = head & tail
+    else:
+      if tail.len > 0 and tail[0] in {DirSep, AltSep}:
+        result = head & tail
+      else:
+        result = head & DirSep & tail
+
+proc joinPath*(parts: varargs[string]): string {.noSideEffect,
+  rtl, extern: "nos$1OpenArray".} =
+  ## The same as `joinPath(head, tail) proc`_,
+  ## but works with any number of directory parts.
+  ##
+  ## You need to pass at least one element or the proc
+  ## will assert in debug builds and crash on release builds.
+  ##
+  ## See also:
+  ## * `joinPath(head, tail) proc`_
+  ## * `/ proc`_
+  ## * `/../ proc`_
+  ## * `splitPath proc`_
+  runnableExamples:
+    when defined(posix):
+      assert joinPath("a") == "a"
+      assert joinPath("a", "b", "c") == "a/b/c"
+      assert joinPath("usr/lib", "../../var", "log") == "var/log"
+
+  var estimatedLen = 0
+  for p in parts: estimatedLen += p.len
+  result = newStringOfCap(estimatedLen)
+  var state = 0
+  for i in 0..high(parts):
+    joinPathImpl(result, state, parts[i])
+
+proc `/`*(head, tail: string): string {.noSideEffect, inline.} =
+  ## The same as `joinPath(head, tail) proc`_.
+  ##
+  ## See also:
+  ## * `/../ proc`_
+  ## * `joinPath(head, tail) proc`_
+  ## * `joinPath(parts: varargs[string]) proc`_
+  ## * `splitPath proc`_
+  ## * `uri.combine proc <uri.html#combine,Uri,Uri>`_
+  ## * `uri./ proc <uri.html#/,Uri,string>`_
+  runnableExamples:
+    when defined(posix):
+      assert "usr" / "" == "usr"
+      assert "" / "lib" == "lib"
+      assert "" / "/lib" == "/lib"
+      assert "usr/" / "/lib/" == "usr/lib/"
+      assert "usr" / "lib" / "../bin" == "usr/bin"
+
+  result = joinPath(head, tail)
+
+when doslikeFileSystem:
+  import std/private/ntpath
+
+proc splitPath*(path: string): tuple[head, tail: string] {.
+  noSideEffect, rtl, extern: "nos$1".} =
+  ## Splits a directory into `(head, tail)` tuple, so that
+  ## ``head / tail == path`` (except for edge cases like "/usr").
+  ##
+  ## See also:
+  ## * `joinPath(head, tail) proc`_
+  ## * `joinPath(parts: varargs[string]) proc`_
+  ## * `/ proc`_
+  ## * `/../ proc`_
+  ## * `relativePath proc`_
+  runnableExamples:
+    assert splitPath("usr/local/bin") == ("usr/local", "bin")
+    assert splitPath("usr/local/bin/") == ("usr/local/bin", "")
+    assert splitPath("/bin/") == ("/bin", "")
+    when (NimMajor, NimMinor) <= (1, 0):
+      assert splitPath("/bin") == ("", "bin")
+    else:
+      assert splitPath("/bin") == ("/", "bin")
+    assert splitPath("bin") == ("", "bin")
+    assert splitPath("") == ("", "")
+
+  when doslikeFileSystem:
+    let (drive, splitpath) = splitDrive(path)
+    let stop = drive.len
+  else:
+    const stop = 0
+
+  var sepPos = -1
+  for i in countdown(len(path)-1, stop):
+    if path[i] in {DirSep, AltSep}:
+      sepPos = i
+      break
+  if sepPos >= 0:
+    result.head = substr(path, 0,
+      when (NimMajor, NimMinor) <= (1, 0):
+        sepPos-1
+      else:
+        if likely(sepPos >= 1): sepPos-1 else: 0
+    )
+    result.tail = substr(path, sepPos+1)
+  else:
+    when doslikeFileSystem:
+      result.head = drive
+      result.tail = splitpath
+    else:
+      result.head = ""
+      result.tail = path
+
+proc isAbsolute*(path: string): bool {.rtl, noSideEffect, extern: "nos$1", raises: [].} =
+  ## Checks whether a given `path` is absolute.
+  ##
+  ## On Windows, network paths are considered absolute too.
+  runnableExamples:
+    assert not "".isAbsolute
+    assert not ".".isAbsolute
+    when defined(posix):
+      assert "/".isAbsolute
+      assert not "a/".isAbsolute
+      assert "/a/".isAbsolute
+
+  if len(path) == 0: return false
+
+  when doslikeFileSystem:
+    var len = len(path)
+    result = (path[0] in {'/', '\\'}) or
+              (len > 1 and path[0] in {'a'..'z', 'A'..'Z'} and path[1] == ':')
+  elif defined(macos):
+    # according to https://perldoc.perl.org/File/Spec/Mac.html `:a` is a relative path
+    result = path[0] != ':'
+  elif defined(RISCOS):
+    result = path[0] == '$'
+  elif defined(posix):
+    result = path[0] == '/'
+  elif defined(nodejs):
+    {.emit: [result," = require(\"path\").isAbsolute(",path.cstring,");"].}
+  else:
+    raiseAssert "unreachable" # if ever hits here, adapt as needed
+
+when FileSystemCaseSensitive:
+  template `!=?`(a, b: char): bool = a != b
+else:
+  template `!=?`(a, b: char): bool = toLowerAscii(a) != toLowerAscii(b)
+
+when doslikeFileSystem:
+  proc isAbsFromCurrentDrive(path: string): bool {.noSideEffect, raises: [].} =
+    ## An absolute path from the root of the current drive (e.g. "\foo")
+    path.len > 0 and
+    (path[0] == AltSep or
+     (path[0] == DirSep and
+      (path.len == 1 or path[1] notin {DirSep, AltSep, ':'})))
+
+  proc sameRoot(path1, path2: string): bool {.noSideEffect, raises: [].} =
+    ## Return true if path1 and path2 have a same root.
+    ##
+    ## Detail of Windows path formats:
+    ## https://docs.microsoft.com/en-us/dotnet/standard/io/file-path-formats
+
+    assert(isAbsolute(path1))
+    assert(isAbsolute(path2))
+
+    if isAbsFromCurrentDrive(path1) and isAbsFromCurrentDrive(path2):
+      result = true
+    elif cmpIgnoreCase(splitDrive(path1).drive, splitDrive(path2).drive) == 0:
+      result = true
+    else:
+      result = false
+
+proc relativePath*(path, base: string, sep = DirSep): string {.
+  rtl, extern: "nos$1".} =
+  ## Converts `path` to a path relative to `base`.
+  ##
+  ## The `sep` (default: DirSep_) is used for the path normalizations,
+  ## this can be useful to ensure the relative path only contains `'/'`
+  ## so that it can be used for URL constructions.
+  ##
+  ## On Windows, if a root of `path` and a root of `base` are different,
+  ## returns `path` as is because it is impossible to make a relative path.
+  ## That means an absolute path can be returned.
+  ##
+  ## See also:
+  ## * `splitPath proc`_
+  ## * `parentDir proc`_
+  ## * `tailDir proc`_
+  runnableExamples:
+    assert relativePath("/Users/me/bar/z.nim", "/Users/other/bad", '/') == "../../me/bar/z.nim"
+    assert relativePath("/Users/me/bar/z.nim", "/Users/other", '/') == "../me/bar/z.nim"
+    when not doslikeFileSystem: # On Windows, UNC-paths start with `//`
+      assert relativePath("/Users///me/bar//z.nim", "//Users/", '/') == "me/bar/z.nim"
+    assert relativePath("/Users/me/bar/z.nim", "/Users/me", '/') == "bar/z.nim"
+    assert relativePath("", "/users/moo", '/') == ""
+    assert relativePath("foo", ".", '/') == "foo"
+    assert relativePath("foo", "foo", '/') == "."
+
+  if path.len == 0: return ""
+  var base = if base == ".": "" else: base
+  var path = path
+  path.normalizePathAux
+  base.normalizePathAux
+  let a1 = isAbsolute(path)
+  let a2 = isAbsolute(base)
+  if a1 and not a2:
+    base = absolutePathInternal(base)
+  elif a2 and not a1:
+    path = absolutePathInternal(path)
+
+  when doslikeFileSystem:
+    if isAbsolute(path) and isAbsolute(base):
+      if not sameRoot(path, base):
+        return path
+
+  var f = default PathIter
+  var b = default PathIter
+  var ff = (0, -1)
+  var bb = (0, -1) # (int, int)
+  result = newStringOfCap(path.len)
+  # skip the common prefix:
+  while f.hasNext(path) and b.hasNext(base):
+    ff = next(f, path)
+    bb = next(b, base)
+    let diff = ff[1] - ff[0]
+    if diff != bb[1] - bb[0]: break
+    var same = true
+    for i in 0..diff:
+      if path[i + ff[0]] !=? base[i + bb[0]]:
+        same = false
+        break
+    if not same: break
+    ff = (0, -1)
+    bb = (0, -1)
+  #  for i in 0..diff:
+  #    result.add base[i + bb[0]]
+
+  # /foo/bar/xxx/ -- base
+  # /foo/bar/baz  -- path path
+  #   ../baz
+  # every directory that is in 'base', needs to add '..'
+  while true:
+    if bb[1] >= bb[0]:
+      if result.len > 0 and result[^1] != sep:
+        result.add sep
+      result.add ".."
+    if not b.hasNext(base): break
+    bb = b.next(base)
+
+  # add the rest of 'path':
+  while true:
+    if ff[1] >= ff[0]:
+      if result.len > 0 and result[^1] != sep:
+        result.add sep
+      for i in 0..ff[1] - ff[0]:
+        result.add path[i + ff[0]]
+    if not f.hasNext(path): break
+    ff = f.next(path)
+
+  when not defined(nimOldRelativePathBehavior):
+    if result.len == 0: result.add "."
+
+proc isRelativeTo*(path: string, base: string): bool {.since: (1, 1).} =
+  ## Returns true if `path` is relative to `base`.
+  runnableExamples:
+    doAssert isRelativeTo("./foo//bar", "foo")
+    doAssert isRelativeTo("foo/bar", ".")
+    doAssert isRelativeTo("/foo/bar.nim", "/foo/bar.nim")
+    doAssert not isRelativeTo("foo/bar.nims", "foo/bar.nim")
+  let path = path.normalizePath
+  let base = base.normalizePath
+  let ret = relativePath(path, base)
+  result = path.len > 0 and not ret.startsWith ".."
+
+proc parentDirPos(path: string): int =
+  var q = 1
+  if len(path) >= 1 and path[len(path)-1] in {DirSep, AltSep}: q = 2
+  for i in countdown(len(path)-q, 0):
+    if path[i] in {DirSep, AltSep}: return i
+  result = -1
+
+proc parentDir*(path: string): string {.
+  noSideEffect, rtl, extern: "nos$1".} =
+  ## Returns the parent directory of `path`.
+  ##
+  ## This is similar to ``splitPath(path).head`` when ``path`` doesn't end
+  ## in a dir separator, but also takes care of path normalizations.
+  ## The remainder can be obtained with `lastPathPart(path) proc`_.
+  ##
+  ## See also:
+  ## * `relativePath proc`_
+  ## * `splitPath proc`_
+  ## * `tailDir proc`_
+  ## * `parentDirs iterator`_
+  runnableExamples:
+    assert parentDir("") == ""
+    when defined(posix):
+      assert parentDir("/usr/local/bin") == "/usr/local"
+      assert parentDir("foo/bar//") == "foo"
+      assert parentDir("//foo//bar//.") == "/foo"
+      assert parentDir("./foo") == "."
+      assert parentDir("/./foo//./") == "/"
+      assert parentDir("a//./") == "."
+      assert parentDir("a/b/c/..") == "a"
+  result = pathnorm.normalizePath(path)
+  when doslikeFileSystem:
+    let (drive, splitpath) = splitDrive(result)
+    result = splitpath
+  var sepPos = parentDirPos(result)
+  if sepPos >= 0:
+    result = substr(result, 0, sepPos)
+    normalizePathEnd(result)
+  elif result == ".." or result == "." or result.len == 0 or result[^1] in {DirSep, AltSep}:
+    # `.` => `..` and .. => `../..`(etc) would be a sensible alternative
+    # `/` => `/` (as done with splitFile) would be a sensible alternative
+    result = ""
+  else:
+    result = "."
+  when doslikeFileSystem:
+    if result.len == 0:
+      discard
+    elif drive.len > 0 and result.len == 1 and result[0] in {DirSep, AltSep}:
+      result = drive
+    else:
+      result = drive & result
+
+proc tailDir*(path: string): string {.
+  noSideEffect, rtl, extern: "nos$1".} =
+  ## Returns the tail part of `path`.
+  ##
+  ## See also:
+  ## * `relativePath proc`_
+  ## * `splitPath proc`_
+  ## * `parentDir proc`_
+  runnableExamples:
+    assert tailDir("/bin") == "bin"
+    assert tailDir("bin") == ""
+    assert tailDir("bin/") == ""
+    assert tailDir("/usr/local/bin") == "usr/local/bin"
+    assert tailDir("//usr//local//bin//") == "usr//local//bin//"
+    assert tailDir("./usr/local/bin") == "usr/local/bin"
+    assert tailDir("usr/local/bin") == "local/bin"
+
+  var i = 0
+  when doslikeFileSystem:
+    let (drive, splitpath) = path.splitDrive
+    if drive != "":
+      return splitpath.strip(chars = {DirSep, AltSep}, trailing = false)
+  while i < len(path):
+    if path[i] in {DirSep, AltSep}:
+      while i < len(path) and path[i] in {DirSep, AltSep}: inc i
+      return substr(path, i)
+    inc i
+  result = ""
+
+proc isRootDir*(path: string): bool {.
+  noSideEffect, rtl, extern: "nos$1".} =
+  ## Checks whether a given `path` is a root directory.
+  runnableExamples:
+    assert isRootDir("")
+    assert isRootDir(".")
+    assert isRootDir("/")
+    assert isRootDir("a")
+    assert not isRootDir("/a")
+    assert not isRootDir("a/b/c")
+
+  when doslikeFileSystem:
+    if splitDrive(path).path == "":
+      return true
+  result = parentDirPos(path) < 0
+
+iterator parentDirs*(path: string, fromRoot=false, inclusive=true): string =
+  ## Walks over all parent directories of a given `path`.
+  ##
+  ## If `fromRoot` is true (default: false), the traversal will start from
+  ## the file system root directory.
+  ## If `inclusive` is true (default), the original argument will be included
+  ## in the traversal.
+  ##
+  ## Relative paths won't be expanded by this iterator. Instead, it will traverse
+  ## only the directories appearing in the relative path.
+  ##
+  ## See also:
+  ## * `parentDir proc`_
+  ##
+  runnableExamples:
+    let g = "a/b/c"
+
+    for p in g.parentDirs:
+      echo p
+      # a/b/c
+      # a/b
+      # a
+
+    for p in g.parentDirs(fromRoot=true):
+      echo p
+      # a/
+      # a/b/
+      # a/b/c
+
+    for p in g.parentDirs(inclusive=false):
+      echo p
+      # a/b
+      # a
+
+  if not fromRoot:
+    var current = path
+    if inclusive: yield path
+    while true:
+      if current.isRootDir: break
+      current = current.parentDir
+      yield current
+  else:
+    when doslikeFileSystem:
+      let start = path.splitDrive.drive.len
+    else:
+      const start = 0
+    for i in countup(start, path.len - 2): # ignore the last /
+      # deal with non-normalized paths such as /foo//bar//baz
+      if path[i] in {DirSep, AltSep} and
+          (i == 0 or path[i-1] notin {DirSep, AltSep}):
+        yield path.substr(0, i)
+
+    if inclusive: yield path
+
+proc `/../`*(head, tail: string): string {.noSideEffect.} =
+  ## The same as ``parentDir(head) / tail``, unless there is no parent
+  ## directory. Then ``head / tail`` is performed instead.
+  ##
+  ## See also:
+  ## * `/ proc`_
+  ## * `parentDir proc`_
+  runnableExamples:
+    when defined(posix):
+      assert "a/b/c" /../ "d/e" == "a/b/d/e"
+      assert "a" /../ "d/e" == "a/d/e"
+
+  when doslikeFileSystem:
+    let (drive, head) = splitDrive(head)
+  let sepPos = parentDirPos(head)
+  if sepPos >= 0:
+    result = substr(head, 0, sepPos-1) / tail
+  else:
+    result = head / tail
+  when doslikeFileSystem:
+    result = drive / result
+
+proc normExt(ext: string): string =
+  if ext == "" or ext[0] == ExtSep: result = ext # no copy needed here
+  else: result = ExtSep & ext
+
+proc searchExtPos*(path: string): int =
+  ## Returns index of the `'.'` char in `path` if it signifies the beginning
+  ## of the file extension. Returns -1 otherwise.
+  ##
+  ## See also:
+  ## * `splitFile proc`_
+  ## * `extractFilename proc`_
+  ## * `lastPathPart proc`_
+  ## * `changeFileExt proc`_
+  ## * `addFileExt proc`_
+  runnableExamples:
+    assert searchExtPos("a/b/c") == -1
+    assert searchExtPos("c.nim") == 1
+    assert searchExtPos("a/b/c.nim") == 5
+    assert searchExtPos("a.b.c.nim") == 5
+    assert searchExtPos(".nim") == -1
+    assert searchExtPos("..nim") == -1
+    assert searchExtPos("a..nim") == 2
+
+  # Unless there is any char that is not `ExtSep` before last `ExtSep` in the file name,
+  # it is not a file extension.
+  const DirSeps = when doslikeFileSystem: {DirSep, AltSep, ':'} else: {DirSep, AltSep}
+  result = -1
+  var i = path.high
+  while i >= 1:
+    if path[i] == ExtSep:
+      break
+    elif path[i] in DirSeps:
+      return -1 # do not skip over path
+    dec i
+
+  for j in countdown(i - 1, 0):
+    if path[j] in DirSeps:
+      return -1
+    elif path[j] != ExtSep:
+      result = i
+      break
+
+proc splitFile*(path: string): tuple[dir, name, ext: string] {.
+  noSideEffect, rtl, extern: "nos$1".} =
+  ## Splits a filename into `(dir, name, extension)` tuple.
+  ##
+  ## `dir` does not end in DirSep_ unless it's `/`.
+  ## `extension` includes the leading dot.
+  ##
+  ## If `path` has no extension, `ext` is the empty string.
+  ## If `path` has no directory component, `dir` is the empty string.
+  ## If `path` has no filename component, `name` and `ext` are empty strings.
+  ##
+  ## See also:
+  ## * `searchExtPos proc`_
+  ## * `extractFilename proc`_
+  ## * `lastPathPart proc`_
+  ## * `changeFileExt proc`_
+  ## * `addFileExt proc`_
+  runnableExamples:
+    var (dir, name, ext) = splitFile("usr/local/nimc.html")
+    assert dir == "usr/local"
+    assert name == "nimc"
+    assert ext == ".html"
+    (dir, name, ext) = splitFile("/usr/local/os")
+    assert dir == "/usr/local"
+    assert name == "os"
+    assert ext == ""
+    (dir, name, ext) = splitFile("/usr/local/")
+    assert dir == "/usr/local"
+    assert name == ""
+    assert ext == ""
+    (dir, name, ext) = splitFile("/tmp.txt")
+    assert dir == "/"
+    assert name == "tmp"
+    assert ext == ".txt"
+
+  var namePos = 0
+  var dotPos = 0
+  when doslikeFileSystem:
+    let (drive, _) = splitDrive(path)
+    let stop = len(drive)
+    result.dir = drive
+  else:
+    const stop = 0
+  for i in countdown(len(path) - 1, stop):
+    if path[i] in {DirSep, AltSep} or i == 0:
+      if path[i] in {DirSep, AltSep}:
+        result.dir = substr(path, 0, if likely(i >= 1): i - 1 else: 0)
+        namePos = i + 1
+      if dotPos > i:
+        result.name = substr(path, namePos, dotPos - 1)
+        result.ext = substr(path, dotPos)
+      else:
+        result.name = substr(path, namePos)
+      break
+    elif path[i] == ExtSep and i > 0 and i < len(path) - 1 and
+         path[i - 1] notin {DirSep, AltSep} and
+         path[i + 1] != ExtSep and dotPos == 0:
+      dotPos = i
+
+proc extractFilename*(path: string): string {.
+  noSideEffect, rtl, extern: "nos$1".} =
+  ## Extracts the filename of a given `path`.
+  ##
+  ## This is the same as ``name & ext`` from `splitFile(path) proc`_.
+  ##
+  ## See also:
+  ## * `searchExtPos proc`_
+  ## * `splitFile proc`_
+  ## * `lastPathPart proc`_
+  ## * `changeFileExt proc`_
+  ## * `addFileExt proc`_
+  runnableExamples:
+    assert extractFilename("foo/bar/") == ""
+    assert extractFilename("foo/bar") == "bar"
+    assert extractFilename("foo/bar.baz") == "bar.baz"
+
+  if path.len == 0 or path[path.len-1] in {DirSep, AltSep}:
+    result = ""
+  else:
+    result = splitPath(path).tail
+
+proc lastPathPart*(path: string): string {.
+  noSideEffect, rtl, extern: "nos$1".} =
+  ## Like `extractFilename proc`_, but ignores
+  ## trailing dir separator; aka: `baseName`:idx: in some other languages.
+  ##
+  ## See also:
+  ## * `searchExtPos proc`_
+  ## * `splitFile proc`_
+  ## * `extractFilename proc`_
+  ## * `changeFileExt proc`_
+  ## * `addFileExt proc`_
+  runnableExamples:
+    assert lastPathPart("foo/bar/") == "bar"
+    assert lastPathPart("foo/bar") == "bar"
+
+  let path = path.normalizePathEnd(trailingSep = false)
+  result = extractFilename(path)
+
+proc changeFileExt*(filename, ext: string): string {.
+  noSideEffect, rtl, extern: "nos$1".} =
+  ## Changes the file extension to `ext`.
+  ##
+  ## If the `filename` has no extension, `ext` will be added.
+  ## If `ext` == "" then any extension is removed.
+  ##
+  ## `Ext` should be given without the leading `'.'`, because some
+  ## filesystems may use a different character. (Although I know
+  ## of none such beast.)
+  ##
+  ## See also:
+  ## * `searchExtPos proc`_
+  ## * `splitFile proc`_
+  ## * `extractFilename proc`_
+  ## * `lastPathPart proc`_
+  ## * `addFileExt proc`_
+  runnableExamples:
+    assert changeFileExt("foo.bar", "baz") == "foo.baz"
+    assert changeFileExt("foo.bar", "") == "foo"
+    assert changeFileExt("foo", "baz") == "foo.baz"
+
+  var extPos = searchExtPos(filename)
+  if extPos < 0: result = filename & normExt(ext)
+  else: result = substr(filename, 0, extPos-1) & normExt(ext)
+
+proc addFileExt*(filename, ext: string): string {.
+  noSideEffect, rtl, extern: "nos$1".} =
+  ## Adds the file extension `ext` to `filename`, unless
+  ## `filename` already has an extension.
+  ##
+  ## `Ext` should be given without the leading `'.'`, because some
+  ## filesystems may use a different character.
+  ## (Although I know of none such beast.)
+  ##
+  ## See also:
+  ## * `searchExtPos proc`_
+  ## * `splitFile proc`_
+  ## * `extractFilename proc`_
+  ## * `lastPathPart proc`_
+  ## * `changeFileExt proc`_
+  runnableExamples:
+    assert addFileExt("foo.bar", "baz") == "foo.bar"
+    assert addFileExt("foo.bar", "") == "foo.bar"
+    assert addFileExt("foo", "baz") == "foo.baz"
+
+  var extPos = searchExtPos(filename)
+  if extPos < 0: result = filename & normExt(ext)
+  else: result = filename
+
+proc cmpPaths*(pathA, pathB: string): int {.
+  noSideEffect, rtl, extern: "nos$1".} =
+  ## Compares two paths.
+  ##
+  ## On a case-sensitive filesystem this is done
+  ## case-sensitively otherwise case-insensitively. Returns:
+  ##
+  ## | `0` if pathA == pathB
+  ## | `< 0` if pathA < pathB
+  ## | `> 0` if pathA > pathB
+  runnableExamples:
+    when defined(macosx):
+      assert cmpPaths("foo", "Foo") == 0
+    elif defined(posix):
+      assert cmpPaths("foo", "Foo") > 0
+
+  let a = normalizePath(pathA)
+  let b = normalizePath(pathB)
+  if FileSystemCaseSensitive:
+    result = cmp(a, b)
+  else:
+    when defined(nimscript):
+      result = cmpic(a, b)
+    elif defined(nimdoc): discard
+    else:
+      result = cmpIgnoreCase(a, b)
+
+proc unixToNativePath*(path: string, drive=""): string {.
+  noSideEffect, rtl, extern: "nos$1".} =
+  ## Converts an UNIX-like path to a native one.
+  ##
+  ## On an UNIX system this does nothing. Else it converts
+  ## `'/'`, `'.'`, `'..'` to the appropriate things.
+  ##
+  ## On systems with a concept of "drives", `drive` is used to determine
+  ## which drive label to use during absolute path conversion.
+  ## `drive` defaults to the drive of the current working directory, and is
+  ## ignored on systems that do not have a concept of "drives".
+  when defined(unix):
+    result = path
+  else:
+    if path.len == 0: return ""
+
+    var start: int
+    if path[0] == '/':
+      # an absolute path
+      when doslikeFileSystem:
+        if drive != "":
+          result = drive & ":" & DirSep
+        else:
+          result = $DirSep
+      elif defined(macos):
+        result = "" # must not start with ':'
+      else:
+        result = $DirSep
+      start = 1
+    elif path[0] == '.' and (path.len == 1 or path[1] == '/'):
+      # current directory
+      result = $CurDir
+      start = when doslikeFileSystem: 1 else: 2
+    else:
+      result = ""
+      start = 0
+
+    var i = start
+    while i < len(path): # ../../../ --> ::::
+      if i+2 < path.len and path[i] == '.' and path[i+1] == '.' and path[i+2] == '/':
+        # parent directory
+        when defined(macos):
+          if result[high(result)] == ':':
+            add result, ':'
+          else:
+            add result, ParDir
+        else:
+          add result, ParDir & DirSep
+        inc(i, 3)
+      elif path[i] == '/':
+        add result, DirSep
+        inc(i)
+      else:
+        add result, path[i]
+        inc(i)
+
+
+when not defined(nimscript):
+  proc getCurrentDir*(): string {.rtl, extern: "nos$1", tags: [].} =
+    ## Returns the `current working directory`:idx: i.e. where the built
+    ## binary is run.
+    ##
+    ## So the path returned by this proc is determined at run time.
+    ##
+    ## See also:
+    ## * `getHomeDir proc`_
+    ## * `getConfigDir proc`_
+    ## * `getTempDir proc`_
+    ## * `setCurrentDir proc`_
+    ## * `currentSourcePath template <system.html#currentSourcePath.t>`_
+    ## * `getProjectPath proc <macros.html#getProjectPath>`_
+    when defined(nodejs):
+      var ret: cstring
+      {.emit: "`ret` = process.cwd();".}
+      return $ret
+    elif defined(js):
+      raiseAssert "use -d:nodejs to have `getCurrentDir` defined"
+    elif defined(windows):
+      var bufsize = MAX_PATH.int32
+      var res = newWideCString(bufsize)
+      while true:
+        var L = getCurrentDirectoryW(bufsize, res)
+        if L == 0'i32:
+          raiseOSError(osLastError())
+        elif L > bufsize:
+          res = newWideCString(L)
+          bufsize = L
+        else:
+          result = res$L
+          break
+    else:
+      var bufsize = 1024 # should be enough
+      result = newString(bufsize)
+      while true:
+        if getcwd(result.cstring, bufsize) != nil:
+          setLen(result, c_strlen(result.cstring))
+          break
+        else:
+          let err = osLastError()
+          if err.int32 == ERANGE:
+            bufsize = bufsize shl 1
+            doAssert(bufsize >= 0)
+            result = newString(bufsize)
+          else:
+            raiseOSError(osLastError())
+
+proc absolutePath*(path: string, root = getCurrentDir()): string =
+  ## Returns the absolute path of `path`, rooted at `root` (which must be absolute;
+  ## default: current directory).
+  ## If `path` is absolute, return it, ignoring `root`.
+  ##
+  ## See also:
+  ## * `normalizedPath proc`_
+  ## * `normalizePath proc`_
+  runnableExamples:
+    assert absolutePath("a") == getCurrentDir() / "a"
+
+  if isAbsolute(path): path
+  else:
+    if not root.isAbsolute:
+      raise newException(ValueError, "The specified root is not absolute: " & root)
+    joinPath(root, path)
+
+proc absolutePathInternal(path: string): string =
+  absolutePath(path, getCurrentDir())
+
+
+proc normalizePath*(path: var string) {.rtl, extern: "nos$1", tags: [].} =
+  ## Normalize a path.
+  ##
+  ## Consecutive directory separators are collapsed, including an initial double slash.
+  ##
+  ## On relative paths, double dot (`..`) sequences are collapsed if possible.
+  ## On absolute paths they are always collapsed.
+  ##
+  ## .. warning:: URL-encoded and Unicode attempts at directory traversal are not detected.
+  ##   Triple dot is not handled.
+  ##
+  ## See also:
+  ## * `absolutePath proc`_
+  ## * `normalizedPath proc`_ for outplace version
+  ## * `normalizeExe proc`_
+  runnableExamples:
+    when defined(posix):
+      var a = "a///b//..//c///d"
+      a.normalizePath()
+      assert a == "a/c/d"
+
+  path = pathnorm.normalizePath(path)
+  when false:
+    let isAbs = isAbsolute(path)
+    var stack: seq[string] = @[]
+    for p in split(path, {DirSep}):
+      case p
+      of "", ".":
+        continue
+      of "..":
+        if stack.len == 0:
+          if isAbs:
+            discard  # collapse all double dots on absoluta paths
+          else:
+            stack.add(p)
+        elif stack[^1] == "..":
+          stack.add(p)
+        else:
+          discard stack.pop()
+      else:
+        stack.add(p)
+
+    if isAbs:
+      path = DirSep & join(stack, $DirSep)
+    elif stack.len > 0:
+      path = join(stack, $DirSep)
+    else:
+      path = "."
+
+proc normalizePathAux(path: var string) = normalizePath(path)
+
+proc normalizedPath*(path: string): string {.rtl, extern: "nos$1", tags: [].} =
+  ## Returns a normalized path for the current OS.
+  ##
+  ## See also:
+  ## * `absolutePath proc`_
+  ## * `normalizePath proc`_ for the in-place version
+  runnableExamples:
+    when defined(posix):
+      assert normalizedPath("a///b//..//c///d") == "a/c/d"
+  result = pathnorm.normalizePath(path)
+
+proc normalizeExe*(file: var string) {.since: (1, 3, 5).} =
+  ## on posix, prepends `./` if `file` doesn't contain `/` and is not `"", ".", ".."`.
+  runnableExamples:
+    import std/sugar
+    when defined(posix):
+      doAssert "foo".dup(normalizeExe) == "./foo"
+      doAssert "foo/../bar".dup(normalizeExe) == "foo/../bar"
+    doAssert "".dup(normalizeExe) == ""
+  when defined(posix):
+    if file.len > 0 and DirSep notin file and file != "." and file != "..":
+      file = "./" & file
+
+proc sameFile*(path1, path2: string): bool {.rtl, extern: "nos$1",
+  tags: [ReadDirEffect], noWeirdTarget.} =
+  ## Returns true if both pathname arguments refer to the same physical
+  ## file or directory.
+  ##
+  ## Raises `OSError` if any of the files does not
+  ## exist or information about it can not be obtained.
+  ##
+  ## This proc will return true if given two alternative hard-linked or
+  ## sym-linked paths to the same file or directory.
+  ##
+  ## See also:
+  ## * `sameFileContent proc`_
+  when defined(windows):
+    var success = true
+    var f1 = openHandle(path1)
+    var f2 = openHandle(path2)
+
+    var lastErr: OSErrorCode
+    if f1 != INVALID_HANDLE_VALUE and f2 != INVALID_HANDLE_VALUE:
+      var fi1, fi2: BY_HANDLE_FILE_INFORMATION
+
+      if getFileInformationByHandle(f1, addr(fi1)) != 0 and
+         getFileInformationByHandle(f2, addr(fi2)) != 0:
+        result = fi1.dwVolumeSerialNumber == fi2.dwVolumeSerialNumber and
+                 fi1.nFileIndexHigh == fi2.nFileIndexHigh and
+                 fi1.nFileIndexLow == fi2.nFileIndexLow
+      else:
+        lastErr = osLastError()
+        success = false
+    else:
+      lastErr = osLastError()
+      success = false
+
+    discard closeHandle(f1)
+    discard closeHandle(f2)
+
+    if not success: raiseOSError(lastErr, $(path1, path2))
+  else:
+    var a, b: Stat
+    if stat(path1, a) < 0'i32 or stat(path2, b) < 0'i32:
+      raiseOSError(osLastError(), $(path1, path2))
+    else:
+      result = a.st_dev == b.st_dev and a.st_ino == b.st_ino
diff --git a/lib/std/private/osseps.nim b/lib/std/private/osseps.nim
new file mode 100644
index 000000000..f2d49d886
--- /dev/null
+++ b/lib/std/private/osseps.nim
@@ -0,0 +1,113 @@
+# Include file that implements 'DirSep' and friends. Do not import this when
+# you also import `os.nim`!
+
+# Improved based on info in 'compiler/platform.nim'
+
+## .. importdoc:: ospaths2.nim
+
+const
+  doslikeFileSystem* = defined(windows) or defined(OS2) or defined(DOS)
+
+const
+  CurDir* =
+    when defined(macos): ':'
+    elif defined(genode): '/'
+    else: '.'
+    ## The constant character used by the operating system to refer to the
+    ## current directory.
+    ##
+    ## For example: `'.'` for POSIX or `':'` for the classic Macintosh.
+
+  ParDir* =
+    when defined(macos): "::"
+    else: ".."
+    ## The constant string used by the operating system to refer to the
+    ## parent directory.
+    ##
+    ## For example: `".."` for POSIX or `"::"` for the classic Macintosh.
+
+  DirSep* =
+    when defined(macos): ':'
+    elif doslikeFileSystem or defined(vxworks): '\\'
+    elif defined(RISCOS): '.'
+    else: '/'
+    ## The character used by the operating system to separate pathname
+    ## components, for example: `'/'` for POSIX, `':'` for the classic
+    ## Macintosh, and `'\\'` on Windows.
+
+  AltSep* =
+    when doslikeFileSystem: '/'
+    else: DirSep
+    ## An alternative character used by the operating system to separate
+    ## pathname components, or the same as DirSep_ if only one separator
+    ## character exists. This is set to `'/'` on Windows systems
+    ## where DirSep_ is a backslash (`'\\'`).
+
+  PathSep* =
+    when defined(macos) or defined(RISCOS): ','
+    elif doslikeFileSystem or defined(vxworks): ';'
+    elif defined(PalmOS) or defined(MorphOS): ':' # platform has ':' but osseps has ';'
+    else: ':'
+    ## The character conventionally used by the operating system to separate
+    ## search path components (as in PATH), such as `':'` for POSIX
+    ## or `';'` for Windows.
+
+  FileSystemCaseSensitive* =
+    when defined(macos) or defined(macosx) or doslikeFileSystem or defined(vxworks) or
+         defined(PalmOS) or defined(MorphOS): false
+    else: true
+    ## True if the file system is case sensitive, false otherwise. Used by
+    ## `cmpPaths proc`_ to compare filenames properly.
+
+  ExeExt* =
+    when doslikeFileSystem: "exe"
+    elif defined(atari): "tpp"
+    elif defined(netware): "nlm"
+    elif defined(vxworks): "vxe"
+    elif defined(nintendoswitch): "elf"
+    else: ""
+    ## The file extension of native executables. For example:
+    ## `""` for POSIX, `"exe"` on Windows (without a dot).
+
+  ScriptExt* =
+    when doslikeFileSystem: "bat"
+    else: ""
+    ## The file extension of a script file. For example: `""` for POSIX,
+    ## `"bat"` on Windows.
+
+  DynlibFormat* =
+    when defined(macos): "$1.dylib" # platform has $1Lib
+    elif defined(macosx): "lib$1.dylib"
+    elif doslikeFileSystem or defined(atari): "$1.dll"
+    elif defined(MorphOS): "$1.prc"
+    elif defined(PalmOS): "$1.prc" # platform has lib$1.so
+    elif defined(genode): "$1.lib.so"
+    elif defined(netware): "$1.nlm"
+    elif defined(amiga): "$1.Library"
+    else: "lib$1.so"
+    ## The format string to turn a filename into a `DLL`:idx: file (also
+    ## called `shared object`:idx: on some operating systems).
+
+  ExtSep* = '.'
+    ## The character which separates the base filename from the extension;
+    ## for example, the `'.'` in `os.nim`.
+
+  #  MacOS paths
+  #  ===========
+  #  MacOS directory separator is a colon ":" which is the only character not
+  #  allowed in filenames.
+  #
+  #  A path containing no colon or which begins with a colon is a partial
+  #  path.
+  #  E.g. ":kalle:petter" ":kalle" "kalle"
+  #
+  #  All other paths are full (absolute) paths. E.g. "HD:kalle:" "HD:"
+  #  When generating paths, one is safe if one ensures that all partial paths
+  #  begin with a colon, and all full paths end with a colon.
+  #  In full paths the first name (e g HD above) is the name of a mounted
+  #  volume.
+  #  These names are not unique, because, for instance, two diskettes with the
+  #  same names could be inserted. This means that paths on MacOS are not
+  #  waterproof. In case of equal names the first volume found will do.
+  #  Two colons "::" are the relative path to the parent. Three is to the
+  #  grandparent etc.
diff --git a/lib/std/private/ossymlinks.nim b/lib/std/private/ossymlinks.nim
new file mode 100644
index 000000000..c1760c42e
--- /dev/null
+++ b/lib/std/private/ossymlinks.nim
@@ -0,0 +1,78 @@
+include system/inclrtl
+import std/oserrors
+
+import oscommon
+export symlinkExists
+
+when defined(nimPreviewSlimSystem):
+  import std/[syncio, assertions, widestrs]
+
+when weirdTarget:
+  discard
+elif defined(windows):
+  import std/[winlean, times]
+elif defined(posix):
+  import std/posix
+else:
+  {.error: "OS module not ported to your operating system!".}
+
+
+when weirdTarget:
+  {.pragma: noWeirdTarget, error: "this proc is not available on the NimScript/js target".}
+else:
+  {.pragma: noWeirdTarget.}
+
+
+when defined(nimscript):
+  # for procs already defined in scriptconfig.nim
+  template noNimJs(body): untyped = discard
+elif defined(js):
+  {.pragma: noNimJs, error: "this proc is not available on the js target".}
+else:
+  {.pragma: noNimJs.}
+
+## .. importdoc:: os.nim
+
+proc createSymlink*(src, dest: string) {.noWeirdTarget.} =
+  ## Create a symbolic link at `dest` which points to the item specified
+  ## by `src`. On most operating systems, will fail if a link already exists.
+  ##
+  ## .. warning:: Some OS's (such as Microsoft Windows) restrict the creation
+  ##   of symlinks to root users (administrators) or users with developer mode enabled.
+  ##
+  ## See also:
+  ## * `createHardlink proc`_
+  ## * `expandSymlink proc`_
+
+  when defined(windows):
+    const SYMBOLIC_LINK_FLAG_ALLOW_UNPRIVILEGED_CREATE = 2
+    # allows anyone with developer mode on to create a link
+    let flag = dirExists(src).int32 or SYMBOLIC_LINK_FLAG_ALLOW_UNPRIVILEGED_CREATE
+    var wSrc = newWideCString(src)
+    var wDst = newWideCString(dest)
+    if createSymbolicLinkW(wDst, wSrc, flag) == 0 or getLastError() != 0:
+      raiseOSError(osLastError(), $(src, dest))
+  else:
+    if symlink(src, dest) != 0:
+      raiseOSError(osLastError(), $(src, dest))
+
+proc expandSymlink*(symlinkPath: string): string {.noWeirdTarget.} =
+  ## Returns a string representing the path to which the symbolic link points.
+  ##
+  ## On Windows this is a noop, `symlinkPath` is simply returned.
+  ##
+  ## See also:
+  ## * `createSymlink proc`_
+  when defined(windows) or defined(nintendoswitch):
+    result = symlinkPath
+  else:
+    var bufLen = 1024
+    while true:
+      result = newString(bufLen)
+      let len = readlink(symlinkPath.cstring, result.cstring, bufLen)
+      if len < 0:
+        raiseOSError(osLastError(), symlinkPath)
+      if len < bufLen:
+        result.setLen(len)
+        break
+      bufLen = bufLen shl 1
diff --git a/lib/std/private/schubfach.nim b/lib/std/private/schubfach.nim
new file mode 100644
index 000000000..b8c85d2bc
--- /dev/null
+++ b/lib/std/private/schubfach.nim
@@ -0,0 +1,436 @@
+##  Copyright 2020 Alexander Bolz
+##
+##  Distributed under the Boost Software License, Version 1.0.
+##   (See accompanying file LICENSE_1_0.txt or copy at https://www.boost.org/LICENSE_1_0.txt)
+
+# --------------------------------------------------------------------------------------------------
+##  This file contains an implementation of the Schubfach algorithm as described in
+##
+##  \[1] Raffaello Giulietti, "The Schubfach way to render doubles",
+##      https://drive.google.com/open?id=1luHhyQF9zKlM8yJ1nebU0OgVYhfC6CBN
+# --------------------------------------------------------------------------------------------------
+
+import std/private/digitsutils
+
+when defined(nimPreviewSlimSystem):
+  import std/assertions
+
+
+template sf_Assert(x: untyped): untyped =
+  assert(x)
+
+# ==================================================================================================
+#
+# ==================================================================================================
+
+type
+  ValueType = float32
+  BitsType = uint32
+  Single {.bycopy.} = object
+    bits: BitsType
+
+const
+  significandSize: int32 = 24
+  MaxExponent = 128
+  exponentBias: int32 = MaxExponent - 1 + (significandSize - 1)
+  maxIeeeExponent: BitsType = BitsType(2 * MaxExponent - 1)
+  hiddenBit: BitsType = BitsType(1) shl (significandSize - 1)
+  significandMask: BitsType = hiddenBit - 1
+  exponentMask: BitsType = maxIeeeExponent shl (significandSize - 1)
+  signMask: BitsType = not (not BitsType(0) shr 1)
+
+proc constructSingle(bits: BitsType): Single  =
+  result.bits = bits
+
+proc constructSingle(value: ValueType): Single  =
+  result.bits = cast[typeof(result.bits)](value)
+
+proc physicalSignificand(this: Single): BitsType {.noSideEffect.} =
+  return this.bits and significandMask
+
+proc physicalExponent(this: Single): BitsType {.noSideEffect.} =
+  return (this.bits and exponentMask) shr (significandSize - 1)
+
+proc isFinite(this: Single): bool {.noSideEffect.} =
+  return (this.bits and exponentMask) != exponentMask
+
+proc isInf(this: Single): bool {.noSideEffect.} =
+  return (this.bits and exponentMask) == exponentMask and
+      (this.bits and significandMask) == 0
+
+proc isNaN(this: Single): bool {.noSideEffect.} =
+  return (this.bits and exponentMask) == exponentMask and
+      (this.bits and significandMask) != 0
+
+proc isZero(this: Single): bool {.noSideEffect.} =
+  return (this.bits and not signMask) == 0
+
+proc signBit(this: Single): int {.noSideEffect.} =
+  return int((this.bits and signMask) != 0)
+
+# ==================================================================================================
+##  Returns floor(x / 2^n).
+##
+##  Technically, right-shift of negative integers is implementation defined...
+##  Should easily be optimized into SAR (or equivalent) instruction.
+
+proc floorDivPow2(x: int32; n: int32): int32 {.inline.} =
+  return x shr n
+
+##  Returns floor(log_10(2^e))
+##  ```c
+##  static inline int32_t FloorLog10Pow2(int32_t e)
+##  {
+##      SF_ASSERT(e >= -1500);
+##      SF_ASSERT(e <=  1500);
+##      return FloorDivPow2(e * 1262611, 22);
+##  }
+##  ```
+##  Returns floor(log_10(3/4 2^e))
+##  ```c
+##  static inline int32_t FloorLog10ThreeQuartersPow2(int32_t e)
+##  {
+##      SF_ASSERT(e >= -1500);
+##      SF_ASSERT(e <=  1500);
+##      return FloorDivPow2(e * 1262611 - 524031, 22);
+##  }
+##  ```
+##  Returns floor(log_2(10^e))
+
+proc floorLog2Pow10(e: int32): int32 {.inline.} =
+  sf_Assert(e >= -1233)
+  sf_Assert(e <= 1233)
+  return floorDivPow2(e * 1741647, 19)
+
+const
+  kMin: int32 = -31
+  kMax: int32 = 45
+  g: array[kMax - kMin + 1, uint64] = [0x81CEB32C4B43FCF5'u64, 0xA2425FF75E14FC32'u64,
+    0xCAD2F7F5359A3B3F'u64, 0xFD87B5F28300CA0E'u64, 0x9E74D1B791E07E49'u64,
+    0xC612062576589DDB'u64, 0xF79687AED3EEC552'u64, 0x9ABE14CD44753B53'u64,
+    0xC16D9A0095928A28'u64, 0xF1C90080BAF72CB2'u64, 0x971DA05074DA7BEF'u64,
+    0xBCE5086492111AEB'u64, 0xEC1E4A7DB69561A6'u64, 0x9392EE8E921D5D08'u64,
+    0xB877AA3236A4B44A'u64, 0xE69594BEC44DE15C'u64, 0x901D7CF73AB0ACDA'u64,
+    0xB424DC35095CD810'u64, 0xE12E13424BB40E14'u64, 0x8CBCCC096F5088CC'u64,
+    0xAFEBFF0BCB24AAFF'u64, 0xDBE6FECEBDEDD5BF'u64, 0x89705F4136B4A598'u64,
+    0xABCC77118461CEFD'u64, 0xD6BF94D5E57A42BD'u64, 0x8637BD05AF6C69B6'u64,
+    0xA7C5AC471B478424'u64, 0xD1B71758E219652C'u64, 0x83126E978D4FDF3C'u64,
+    0xA3D70A3D70A3D70B'u64, 0xCCCCCCCCCCCCCCCD'u64, 0x8000000000000000'u64,
+    0xA000000000000000'u64, 0xC800000000000000'u64, 0xFA00000000000000'u64,
+    0x9C40000000000000'u64, 0xC350000000000000'u64, 0xF424000000000000'u64,
+    0x9896800000000000'u64, 0xBEBC200000000000'u64, 0xEE6B280000000000'u64,
+    0x9502F90000000000'u64, 0xBA43B74000000000'u64, 0xE8D4A51000000000'u64,
+    0x9184E72A00000000'u64, 0xB5E620F480000000'u64, 0xE35FA931A0000000'u64,
+    0x8E1BC9BF04000000'u64, 0xB1A2BC2EC5000000'u64, 0xDE0B6B3A76400000'u64,
+    0x8AC7230489E80000'u64, 0xAD78EBC5AC620000'u64, 0xD8D726B7177A8000'u64,
+    0x878678326EAC9000'u64, 0xA968163F0A57B400'u64, 0xD3C21BCECCEDA100'u64,
+    0x84595161401484A0'u64, 0xA56FA5B99019A5C8'u64, 0xCECB8F27F4200F3A'u64,
+    0x813F3978F8940985'u64, 0xA18F07D736B90BE6'u64, 0xC9F2C9CD04674EDF'u64,
+    0xFC6F7C4045812297'u64, 0x9DC5ADA82B70B59E'u64, 0xC5371912364CE306'u64,
+    0xF684DF56C3E01BC7'u64, 0x9A130B963A6C115D'u64, 0xC097CE7BC90715B4'u64,
+    0xF0BDC21ABB48DB21'u64, 0x96769950B50D88F5'u64, 0xBC143FA4E250EB32'u64,
+    0xEB194F8E1AE525FE'u64, 0x92EFD1B8D0CF37BF'u64, 0xB7ABC627050305AE'u64,
+    0xE596B7B0C643C71A'u64, 0x8F7E32CE7BEA5C70'u64, 0xB35DBF821AE4F38C'u64]
+
+proc computePow10Single(k: int32): uint64 {.inline.} =
+  ##  There are unique beta and r such that 10^k = beta 2^r and
+  ##  2^63 <= beta < 2^64, namely r = floor(log_2 10^k) - 63 and
+  ##  beta = 2^-r 10^k.
+  ##  Let g = ceil(beta), so (g-1) 2^r < 10^k <= g 2^r, with the latter
+  ##  value being a pretty good overestimate for 10^k.
+  ##  NB: Since for all the required exponents k, we have g < 2^64,
+  ##      all constants can be stored in 128-bit integers.
+  sf_Assert(k >= kMin)
+  sf_Assert(k <= kMax)
+  return g[k - kMin]
+
+proc lo32(x: uint64): uint32 {.inline.} =
+  return cast[uint32](x)
+
+proc hi32(x: uint64): uint32 {.inline.} =
+  return cast[uint32](x shr 32)
+
+when defined(sizeof_Int128):
+  proc roundToOdd(g: uint64; cp: uint32): uint32 {.inline.} =
+    let p: uint128 = uint128(g) * cp
+    let y1: uint32 = lo32(cast[uint64](p shr 64))
+    let y0: uint32 = hi32(cast[uint64](p))
+    return y1 or uint32(y0 > 1)
+
+elif defined(vcc) and defined(cpu64):
+  proc umul128(x, y: uint64, z: ptr uint64): uint64 {.importc: "_umul128", header: "<intrin.h>".}
+  proc roundToOdd(g: uint64; cpHi: uint32): uint32 {.inline.} =
+    var p1: uint64 = 0
+    var p0: uint64 = umul128(g, cpHi, addr(p1))
+    let y1: uint32 = lo32(p1)
+    let y0: uint32 = hi32(p0)
+    return y1 or uint32(y0 > 1)
+
+else:
+  proc roundToOdd(g: uint64; cp: uint32): uint32 {.inline.} =
+    let b01: uint64 = uint64(lo32(g)) * cp
+    let b11: uint64 = uint64(hi32(g)) * cp
+    let hi: uint64 = b11 + hi32(b01)
+    let y1: uint32 = hi32(hi)
+    let y0: uint32 = lo32(hi)
+    return y1 or uint32(y0 > 1)
+
+##  Returns whether value is divisible by 2^e2
+
+proc multipleOfPow2(value: uint32; e2: int32): bool {.inline.} =
+  sf_Assert(e2 >= 0)
+  sf_Assert(e2 <= 31)
+  return (value and ((uint32(1) shl e2) - 1)) == 0
+
+type
+  FloatingDecimal32 {.bycopy.} = object
+    digits: uint32            ##  num_digits <= 9
+    exponent: int32
+
+proc toDecimal32(ieeeSignificand: uint32; ieeeExponent: uint32): FloatingDecimal32 {.
+    inline.} =
+  var c: uint32
+  var q: int32
+  if ieeeExponent != 0:
+    c = hiddenBit or ieeeSignificand
+    q = cast[int32](ieeeExponent) - exponentBias
+    if 0 <= -q and -q < significandSize and multipleOfPow2(c, -q):
+      return FloatingDecimal32(digits: c shr -q, exponent: 0'i32)
+  else:
+    c = ieeeSignificand
+    q = 1 - exponentBias
+  let isEven: bool = (c mod 2 == 0)
+  let lowerBoundaryIsCloser: bool = (ieeeSignificand == 0 and ieeeExponent > 1)
+  ##   const int32_t qb = q - 2;
+  let cbl: uint32 = 4 * c - 2 + uint32(lowerBoundaryIsCloser)
+  let cb: uint32 = 4 * c
+  let cbr: uint32 = 4 * c + 2
+  ##  (q * 1262611         ) >> 22 == floor(log_10(    2^q))
+  ##  (q * 1262611 - 524031) >> 22 == floor(log_10(3/4 2^q))
+  sf_Assert(q >= -1500)
+  sf_Assert(q <= 1500)
+  let k: int32 = floorDivPow2(q * 1262611 - (if lowerBoundaryIsCloser: 524031 else: 0), 22)
+  let h: int32 = q + floorLog2Pow10(-k) + 1
+  sf_Assert(h >= 1)
+  sf_Assert(h <= 4)
+  let pow10: uint64 = computePow10Single(-k)
+  let vbl: uint32 = roundToOdd(pow10, cbl shl h)
+  let vb: uint32 = roundToOdd(pow10, cb shl h)
+  let vbr: uint32 = roundToOdd(pow10, cbr shl h)
+  let lower: uint32 = vbl + uint32(not isEven)
+  let upper: uint32 = vbr - uint32(not isEven)
+  ##  See Figure 4 in [1].
+  ##  And the modifications in Figure 6.
+  let s: uint32 = vb div 4
+  ##  NB: 4 * s == vb & ~3 == vb & -4
+  if s >= 10:
+    let sp: uint32 = s div 10
+    ##  = vb / 40
+    let upInside: bool = lower <= 40 * sp
+    let wpInside: bool = 40 * sp + 40 <= upper
+    ##       if (up_inside || wp_inside) // NB: At most one of u' and w' is in R_v.
+    if upInside != wpInside:
+      return FloatingDecimal32(digits: sp + uint32(wpInside), exponent: k + 1)
+  let uInside: bool = lower <= 4 * s
+  let wInside: bool = 4 * s + 4 <= upper
+  if uInside != wInside:
+    return FloatingDecimal32(digits: s + uint32(wInside), exponent: k)
+  let mid: uint32 = 4 * s + 2
+  ##  = 2(s + t)
+  let roundUp: bool = vb > mid or (vb == mid and (s and 1) != 0)
+  return FloatingDecimal32(digits: s + uint32(roundUp), exponent: k)
+
+## ==================================================================================================
+##  ToChars
+## ==================================================================================================
+
+proc printDecimalDigitsBackwards[T: Ordinal](buf: var openArray[char]; pos: T; output: uint32): int {.inline.} =
+  var output = output
+  var pos = pos
+  var tz = 0
+  ##  number of trailing zeros removed.
+  var nd = 0
+  ##  number of decimal digits processed.
+  ##  At most 9 digits remaining
+  if output >= 10000:
+    let q: uint32 = output div 10000
+    let r: uint32 = output mod 10000
+    output = q
+    dec(pos, 4)
+    if r != 0:
+      let rH: uint32 = r div 100
+      let rL: uint32 = r mod 100
+      utoa2Digits(buf, pos, rH)
+      utoa2Digits(buf, pos + 2, rL)
+      tz = trailingZeros2Digits(if rL == 0: rH else: rL) + (if rL == 0: 2 else: 0)
+    else:
+      tz = 4
+    nd = 4
+  if output >= 100:
+    let q: uint32 = output div 100
+    let r: uint32 = output mod 100
+    output = q
+    dec(pos, 2)
+    utoa2Digits(buf, pos, r)
+    if tz == nd:
+      inc(tz, trailingZeros2Digits(r))
+    inc(nd, 2)
+    if output >= 100:
+      let q2: uint32 = output div 100
+      let r2: uint32 = output mod 100
+      output = q2
+      dec(pos, 2)
+      utoa2Digits(buf, pos, r2)
+      if tz == nd:
+        inc(tz, trailingZeros2Digits(r2))
+      inc(nd, 2)
+  sf_Assert(output >= 1)
+  sf_Assert(output <= 99)
+  if output >= 10:
+    let q: uint32 = output
+    dec(pos, 2)
+    utoa2Digits(buf, pos, q)
+    if tz == nd:
+      inc(tz, trailingZeros2Digits(q))
+  else:
+    let q: uint32 = output
+    sf_Assert(q >= 1)
+    sf_Assert(q <= 9)
+    dec(pos)
+    buf[pos] = chr(uint32('0') + q)
+  return tz
+
+proc decimalLength(v: uint32): int {.inline.} =
+  sf_Assert(v >= 1)
+  sf_Assert(v <= 999999999'u)
+  if v >= 100000000'u:
+    return 9
+  if v >= 10000000'u:
+    return 8
+  if v >= 1000000'u:
+    return 7
+  if v >= 100000'u:
+    return 6
+  if v >= 10000'u:
+    return 5
+  if v >= 1000'u:
+    return 4
+  if v >= 100'u:
+    return 3
+  if v >= 10'u:
+    return 2
+  return 1
+
+proc formatDigits[T: Ordinal](buffer: var openArray[char]; pos: T; digits: uint32; decimalExponent: int;
+                  forceTrailingDotZero: bool = false): int {.inline.} =
+  const
+    minFixedDecimalPoint: int32 = -4
+    maxFixedDecimalPoint: int32 = 9
+  var pos = pos
+  assert(minFixedDecimalPoint <= -1, "internal error")
+  assert(maxFixedDecimalPoint >= 1, "internal error")
+  sf_Assert(digits >= 1)
+  sf_Assert(digits <= 999999999'u)
+  sf_Assert(decimalExponent >= -99)
+  sf_Assert(decimalExponent <= 99)
+  var numDigits = decimalLength(digits)
+  let decimalPoint = numDigits + decimalExponent
+  let useFixed: bool = minFixedDecimalPoint <= decimalPoint and
+      decimalPoint <= maxFixedDecimalPoint
+  ##  Prepare the buffer.
+  ##  Avoid calling memset/memcpy with variable arguments below...
+  for i in 0..<32: buffer[pos+i] = '0'
+  assert(minFixedDecimalPoint >= -30, "internal error")
+  assert(maxFixedDecimalPoint <= 32, "internal error")
+  var decimalDigitsPosition: int
+  if useFixed:
+    if decimalPoint <= 0:
+      ##  0.[000]digits
+      decimalDigitsPosition = 2 - decimalPoint
+    else:
+      ##  dig.its
+      ##  digits[000]
+      decimalDigitsPosition = 0
+  else:
+    ##  dE+123 or d.igitsE+123
+    decimalDigitsPosition = 1
+  var digitsEnd = pos + decimalDigitsPosition + numDigits
+  let tz = printDecimalDigitsBackwards(buffer, digitsEnd, digits)
+  dec(digitsEnd, tz)
+  dec(numDigits, tz)
+  ##   decimal_exponent += tz; // => decimal_point unchanged.
+  if useFixed:
+    if decimalPoint <= 0:
+      ##  0.[000]digits
+      buffer[pos+1] = '.'
+      pos = digitsEnd
+    elif decimalPoint < numDigits:
+      ##  dig.its
+      for i in countdown(7, 0):
+        buffer[i + decimalPoint + 1] = buffer[i + decimalPoint]
+      buffer[pos+decimalPoint] = '.'
+      pos = digitsEnd + 1
+    else:
+      ##  digits[000]
+      inc(pos, decimalPoint)
+      if forceTrailingDotZero:
+        buffer[pos] = '.'
+        buffer[pos+1] = '0'
+        inc(pos, 2)
+  else:
+    buffer[pos] = buffer[pos+1]
+    if numDigits == 1:
+      ##  dE+123
+      inc(pos)
+    else:
+      ##  d.igitsE+123
+      buffer[pos+1] = '.'
+      pos = digitsEnd
+    let scientificExponent = decimalPoint - 1
+    ##       SF_ASSERT(scientific_exponent != 0);
+    buffer[pos] = 'e'
+    buffer[pos+1] = if scientificExponent < 0: '-' else: '+'
+    inc(pos, 2)
+    let k: uint32 = cast[uint32](if scientificExponent < 0: -scientificExponent else: scientificExponent)
+    if k < 10:
+      buffer[pos] = chr(uint32('0') + k)
+      inc pos
+    else:
+      utoa2Digits(buffer, pos, k)
+      inc(pos, 2)
+  return pos
+
+proc float32ToChars*(buffer: var openArray[char]; v: float32; forceTrailingDotZero = false): int {.
+    inline.} =
+  let significand: uint32 = physicalSignificand(constructSingle(v))
+  let exponent: uint32 = physicalExponent(constructSingle(v))
+  var pos = 0
+  if exponent != maxIeeeExponent:
+    ##  Finite
+    buffer[pos] = '-'
+    inc(pos, signBit(constructSingle(v)))
+    if exponent != 0 or significand != 0:
+      ##  != 0
+      let dec: auto = toDecimal32(significand, exponent)
+      return formatDigits(buffer, pos, dec.digits, dec.exponent.int, forceTrailingDotZero)
+    else:
+      buffer[pos] = '0'
+      buffer[pos+1] = '.'
+      buffer[pos+2] = '0'
+      buffer[pos+3] = ' '
+      inc(pos, if forceTrailingDotZero: 3 else: 1)
+      return pos
+  if significand == 0:
+    buffer[pos] = '-'
+    inc(pos, signBit(constructSingle(v)))
+    buffer[pos] = 'i'
+    buffer[pos+1] = 'n'
+    buffer[pos+2] = 'f'
+    buffer[pos+3] = ' '
+    return pos + 3
+  else:
+    buffer[pos] = 'n'
+    buffer[pos+1] = 'a'
+    buffer[pos+2] = 'n'
+    buffer[pos+3] = ' '
+    return pos + 3
diff --git a/lib/std/private/since.nim b/lib/std/private/since.nim
index 5b22b6391..720120f11 100644
--- a/lib/std/private/since.nim
+++ b/lib/std/private/since.nim
@@ -1,5 +1,5 @@
 ##[
-`since` is used to emulate older versions of nim stdlib with `--useVersion`,
+`since` is used to emulate older versions of nim stdlib,
 see `tuse_version.nim`.
 
 If a symbol `foo` is added in version `(1,3,5)`, use `{.since: (1.3.5).}`, not
@@ -15,19 +15,19 @@ The emulation cannot be 100% faithful and to avoid adding too much complexity,
 template since*(version: (int, int), body: untyped) {.dirty.} =
   ## Evaluates `body` if the ``(NimMajor, NimMinor)`` is greater than
   ## or equal to `version`. Usage:
-  ##
-  ## .. code-block:: Nim
+  ##   ```Nim
   ##   proc fun*() {.since: (1, 3).}
   ##   since (1, 3): fun()
+  ##   ```
   when (NimMajor, NimMinor) >= version:
     body
 
 template since*(version: (int, int, int), body: untyped) {.dirty.} =
   ## Evaluates `body` if ``(NimMajor, NimMinor, NimPatch)`` is greater than 
   ## or equal to `version`. Usage:
-  ##
-  ## .. code-block:: Nim
+  ##   ```Nim
   ##   proc fun*() {.since: (1, 3, 1).}
   ##   since (1, 3, 1): fun()
+  ##   ```
   when (NimMajor, NimMinor, NimPatch) >= version:
     body
diff --git a/lib/std/private/strimpl.nim b/lib/std/private/strimpl.nim
index 7d42a7cf8..f8c9236a5 100644
--- a/lib/std/private/strimpl.nim
+++ b/lib/std/private/strimpl.nim
@@ -74,3 +74,40 @@ template endsWithImpl*[T: string | cstring](s, suffix: T) =
 
 func cmpNimIdentifier*[T: string | cstring](a, b: T): int =
   cmpIgnoreStyleImpl(a, b, true)
+
+func c_memchr(cstr: pointer, c: char, n: csize_t): pointer {.
+              importc: "memchr", header: "<string.h>".}
+func c_strstr(haystack, needle: cstring): cstring {.
+  importc: "strstr", header: "<string.h>".}
+
+
+func find*(s: cstring, sub: char, start: Natural = 0, last = 0): int =
+  ## Searches for `sub` in `s` inside the range `start..last` (both ends included).
+  ## If `last` is unspecified, it defaults to `s.high` (the last element).
+  ##
+  ## Searching is case-sensitive. If `sub` is not in `s`, -1 is returned.
+  ## Otherwise the index returned is relative to `s[0]`, not `start`.
+  ## Use `s[start..last].rfind` for a `start`-origin index.
+  let last = if last == 0: s.high else: last
+  let L = last-start+1
+  if L > 0:
+    let found = c_memchr(s[start].unsafeAddr, sub, cast[csize_t](L))
+    if not found.isNil:
+      return cast[int](found) -% cast[int](s)
+  return -1
+
+func find*(s, sub: cstring, start: Natural = 0, last = 0): int =
+  ## Searches for `sub` in `s` inside the range `start..last` (both ends included).
+  ## If `last` is unspecified, it defaults to `s.high` (the last element).
+  ##
+  ## Searching is case-sensitive. If `sub` is not in `s`, -1 is returned.
+  ## Otherwise the index returned is relative to `s[0]`, not `start`.
+  ## Use `s[start..last].find` for a `start`-origin index.
+  if sub.len > s.len - start: return -1
+  if sub.len == 1: return find(s, sub[0], start, last)
+  if last == 0 and s.len > start:
+    let found = c_strstr(cast[cstring](s[start].unsafeAddr), sub)
+    if not found.isNil:
+      result = cast[int](found) -% cast[int](s)
+    else:
+      result = -1
diff --git a/lib/std/private/syslocks.nim b/lib/std/private/syslocks.nim
new file mode 100644
index 000000000..e19ec2c04
--- /dev/null
+++ b/lib/std/private/syslocks.nim
@@ -0,0 +1,234 @@
+#
+#
+#            Nim's Runtime Library
+#        (c) Copyright 2012 Andreas Rumpf
+#
+#    See the file "copying.txt", included in this
+#    distribution, for details about the copyright.
+#
+
+# Low level system locks and condition vars.
+
+{.push stackTrace: off.}
+
+when defined(windows):
+  type
+    Handle = int
+
+    SysLock* {.importc: "CRITICAL_SECTION",
+              header: "<windows.h>", final, pure, byref.} = object # CRITICAL_SECTION in WinApi
+      DebugInfo: pointer
+      LockCount: int32
+      RecursionCount: int32
+      OwningThread: int
+      LockSemaphore: int
+      SpinCount: int
+
+    SysCond* {.importc: "RTL_CONDITION_VARIABLE", header: "<windows.h>", byref.} = object
+      thePtr {.importc: "Ptr".} : Handle
+
+  proc initSysLock*(L: var SysLock) {.importc: "InitializeCriticalSection",
+                                     header: "<windows.h>".}
+    ## Initializes the lock `L`.
+
+  proc tryAcquireSysAux(L: var SysLock): int32 {.importc: "TryEnterCriticalSection",
+                                                 header: "<windows.h>".}
+    ## Tries to acquire the lock `L`.
+
+  proc tryAcquireSys*(L: var SysLock): bool {.inline.} =
+    result = tryAcquireSysAux(L) != 0'i32
+
+  proc acquireSys*(L: var SysLock) {.importc: "EnterCriticalSection",
+                                    header: "<windows.h>".}
+    ## Acquires the lock `L`.
+
+  proc releaseSys*(L: var SysLock) {.importc: "LeaveCriticalSection",
+                                    header: "<windows.h>".}
+    ## Releases the lock `L`.
+
+  proc deinitSys*(L: SysLock) {.importc: "DeleteCriticalSection",
+                                   header: "<windows.h>".}
+
+  proc initializeConditionVariable(
+    conditionVariable: var SysCond
+  ) {.stdcall, noSideEffect, dynlib: "kernel32", importc: "InitializeConditionVariable".}
+
+  proc sleepConditionVariableCS(
+    conditionVariable: var SysCond,
+    PCRITICAL_SECTION: var SysLock,
+    dwMilliseconds: int
+  ): int32 {.stdcall, noSideEffect, dynlib: "kernel32", importc: "SleepConditionVariableCS".}
+
+
+  proc signalSysCond*(hEvent: var SysCond) {.stdcall, noSideEffect,
+    dynlib: "kernel32", importc: "WakeConditionVariable".}
+
+  proc broadcastSysCond*(hEvent: var SysCond) {.stdcall, noSideEffect,
+    dynlib: "kernel32", importc: "WakeAllConditionVariable".}
+
+  proc initSysCond*(cond: var SysCond) {.inline.} =
+    initializeConditionVariable(cond)
+  proc deinitSysCond*(cond: SysCond) {.inline.} =
+    discard
+  proc waitSysCond*(cond: var SysCond, lock: var SysLock) =
+    discard sleepConditionVariableCS(cond, lock, -1'i32)
+
+elif defined(genode):
+  const
+    Header = "genode_cpp/syslocks.h"
+  type
+    SysLock* {.importcpp: "Nim::SysLock", pure, final,
+              header: Header.} = object
+    SysCond* {.importcpp: "Nim::SysCond", pure, final,
+              header: Header.} = object
+
+  proc initSysLock*(L: var SysLock) = discard
+  proc deinitSys*(L: SysLock) = discard
+  proc acquireSys*(L: var SysLock) {.noSideEffect, importcpp.}
+  proc tryAcquireSys*(L: var SysLock): bool {.noSideEffect, importcpp.}
+  proc releaseSys*(L: var SysLock) {.noSideEffect, importcpp.}
+
+  proc initSysCond*(L: var SysCond) = discard
+  proc deinitSysCond*(L: SysCond) = discard
+  proc waitSysCond*(cond: var SysCond, lock: var SysLock) {.
+    noSideEffect, importcpp.}
+  proc signalSysCond*(cond: var SysCond) {.
+    noSideEffect, importcpp.}
+  proc broadcastSysCond*(cond: var SysCond) {.
+    noSideEffect, importcpp.}
+
+else:
+  type
+    SysLockObj {.importc: "pthread_mutex_t", pure, final,
+               header: """#include <sys/types.h>
+                          #include <pthread.h>""", byref.} = object
+      when defined(linux) and defined(amd64):
+        abi: array[40 div sizeof(clong), clong]
+
+    SysLockAttr* {.importc: "pthread_mutexattr_t", pure, final
+               header: """#include <sys/types.h>
+                          #include <pthread.h>""".} = object
+      when defined(linux) and defined(amd64):
+        abi: array[4 div sizeof(cint), cint]  # actually a cint
+
+    SysCondObj {.importc: "pthread_cond_t", pure, final,
+               header: """#include <sys/types.h>
+                          #include <pthread.h>""", byref.} = object
+      when defined(linux) and defined(amd64):
+        abi: array[48 div sizeof(clonglong), clonglong]
+
+    SysCondAttr {.importc: "pthread_condattr_t", pure, final
+               header: """#include <sys/types.h>
+                          #include <pthread.h>""".} = object
+      when defined(linux) and defined(amd64):
+        abi: array[4 div sizeof(cint), cint]  # actually a cint
+
+    SysLockType = distinct cint
+
+  proc initSysLockAux(L: var SysLockObj, attr: ptr SysLockAttr) {.
+    importc: "pthread_mutex_init", header: "<pthread.h>", noSideEffect.}
+  proc deinitSysAux(L: SysLockObj) {.noSideEffect,
+    importc: "pthread_mutex_destroy", header: "<pthread.h>".}
+
+  proc acquireSysAux(L: var SysLockObj) {.noSideEffect,
+    importc: "pthread_mutex_lock", header: "<pthread.h>".}
+  proc tryAcquireSysAux(L: var SysLockObj): cint {.noSideEffect,
+    importc: "pthread_mutex_trylock", header: "<pthread.h>".}
+
+  proc releaseSysAux(L: var SysLockObj) {.noSideEffect,
+    importc: "pthread_mutex_unlock", header: "<pthread.h>".}
+
+  when defined(ios):
+    # iOS will behave badly if sync primitives are moved in memory. In order
+    # to prevent this once and for all, we're doing an extra malloc when
+    # initializing the primitive.
+    type
+      SysLock* = ptr SysLockObj
+      SysCond* = ptr SysCondObj
+
+    when not declared(c_malloc):
+      proc c_malloc(size: csize_t): pointer {.
+        importc: "malloc", header: "<stdlib.h>".}
+      proc c_free(p: pointer) {.
+        importc: "free", header: "<stdlib.h>".}
+
+    proc initSysLock*(L: var SysLock, attr: ptr SysLockAttr = nil) =
+      L = cast[SysLock](c_malloc(csize_t(sizeof(SysLockObj))))
+      initSysLockAux(L[], attr)
+
+    proc deinitSys*(L: SysLock) =
+      deinitSysAux(L[])
+      c_free(L)
+
+    template acquireSys*(L: var SysLock) =
+      acquireSysAux(L[])
+    template tryAcquireSys*(L: var SysLock): bool =
+      tryAcquireSysAux(L[]) == 0'i32
+    template releaseSys*(L: var SysLock) =
+      releaseSysAux(L[])
+  else:
+    type
+      SysLock* = SysLockObj
+      SysCond* = SysCondObj
+
+    template initSysLock*(L: var SysLock, attr: ptr SysLockAttr = nil) =
+      initSysLockAux(L, attr)
+    template deinitSys*(L: SysLock) =
+      deinitSysAux(L)
+    template acquireSys*(L: var SysLock) =
+      acquireSysAux(L)
+    template tryAcquireSys*(L: var SysLock): bool =
+      tryAcquireSysAux(L) == 0'i32
+    template releaseSys*(L: var SysLock) =
+      releaseSysAux(L)
+
+  # rlocks
+  var SysLockType_Reentrant* {.importc: "PTHREAD_MUTEX_RECURSIVE",
+    header: "<pthread.h>".}: SysLockType
+  proc initSysLockAttr*(a: var SysLockAttr) {.
+    importc: "pthread_mutexattr_init", header: "<pthread.h>", noSideEffect.}
+  proc setSysLockType*(a: var SysLockAttr, t: SysLockType) {.
+    importc: "pthread_mutexattr_settype", header: "<pthread.h>", noSideEffect.}
+
+  # locks
+  proc initSysCondAux(cond: var SysCondObj, cond_attr: ptr SysCondAttr = nil) {.
+    importc: "pthread_cond_init", header: "<pthread.h>", noSideEffect.}
+  proc deinitSysCondAux(cond: SysCondObj) {.noSideEffect,
+    importc: "pthread_cond_destroy", header: "<pthread.h>".}
+
+  proc waitSysCondAux(cond: var SysCondObj, lock: var SysLockObj): cint {.
+    importc: "pthread_cond_wait", header: "<pthread.h>", noSideEffect.}
+  proc signalSysCondAux(cond: var SysCondObj) {.
+    importc: "pthread_cond_signal", header: "<pthread.h>", noSideEffect.}
+  proc broadcastSysCondAux(cond: var SysCondObj) {.
+    importc: "pthread_cond_broadcast", header: "<pthread.h>", noSideEffect.}
+
+  when defined(ios):
+    proc initSysCond*(cond: var SysCond, cond_attr: ptr SysCondAttr = nil) =
+      cond = cast[SysCond](c_malloc(csize_t(sizeof(SysCondObj))))
+      initSysCondAux(cond[], cond_attr)
+
+    proc deinitSysCond*(cond: SysCond) =
+      deinitSysCondAux(cond[])
+      c_free(cond)
+
+    template waitSysCond*(cond: var SysCond, lock: var SysLock) =
+      discard waitSysCondAux(cond[], lock[])
+    template signalSysCond*(cond: var SysCond) =
+      signalSysCondAux(cond[])
+    template broadcastSysCond*(cond: var SysCond) =
+      broadcastSysCondAux(cond[])
+  else:
+    template initSysCond*(cond: var SysCond, cond_attr: ptr SysCondAttr = nil) =
+      initSysCondAux(cond, cond_attr)
+    template deinitSysCond*(cond: SysCond) =
+      deinitSysCondAux(cond)
+
+    template waitSysCond*(cond: var SysCond, lock: var SysLock) =
+      discard waitSysCondAux(cond, lock)
+    template signalSysCond*(cond: var SysCond) =
+      signalSysCondAux(cond)
+    template broadcastSysCond*(cond: var SysCond) =
+      broadcastSysCondAux(cond)
+
+{.pop.}
diff --git a/lib/std/private/threadtypes.nim b/lib/std/private/threadtypes.nim
new file mode 100644
index 000000000..a1cdf21dc
--- /dev/null
+++ b/lib/std/private/threadtypes.nim
@@ -0,0 +1,176 @@
+include system/inclrtl
+
+const hasSharedHeap* = defined(boehmgc) or defined(gogc) # don't share heaps; every thread has its own
+
+when defined(windows):
+  type
+    Handle* = int
+    SysThread* = Handle
+    WinThreadProc* = proc (x: pointer): int32 {.stdcall.}
+
+  proc createThread*(lpThreadAttributes: pointer, dwStackSize: int32,
+                     lpStartAddress: WinThreadProc,
+                     lpParameter: pointer,
+                     dwCreationFlags: int32,
+                     lpThreadId: var int32): SysThread {.
+    stdcall, dynlib: "kernel32", importc: "CreateThread".}
+
+  proc winSuspendThread*(hThread: SysThread): int32 {.
+    stdcall, dynlib: "kernel32", importc: "SuspendThread".}
+
+  proc winResumeThread*(hThread: SysThread): int32 {.
+    stdcall, dynlib: "kernel32", importc: "ResumeThread".}
+
+  proc waitForSingleObject*(hHandle: SysThread, dwMilliseconds: int32): int32 {.
+    stdcall, dynlib: "kernel32", importc: "WaitForSingleObject".}
+
+  proc waitForMultipleObjects*(nCount: int32,
+                              lpHandles: ptr SysThread,
+                              bWaitAll: int32,
+                              dwMilliseconds: int32): int32 {.
+    stdcall, dynlib: "kernel32", importc: "WaitForMultipleObjects".}
+
+  proc terminateThread*(hThread: SysThread, dwExitCode: int32): int32 {.
+    stdcall, dynlib: "kernel32", importc: "TerminateThread".}
+
+  proc setThreadAffinityMask*(hThread: SysThread, dwThreadAffinityMask: uint) {.
+    importc: "SetThreadAffinityMask", stdcall, header: "<windows.h>".}
+
+elif defined(genode):
+  const
+    GenodeHeader* = "genode_cpp/threads.h"
+  type
+    SysThread* {.importcpp: "Nim::SysThread",
+                 header: GenodeHeader, final, pure.} = object
+    GenodeThreadProc* = proc (x: pointer) {.noconv.}
+
+  proc initThread*(s: var SysThread,
+                  env: GenodeEnv,
+                  stackSize: culonglong,
+                  entry: GenodeThreadProc,
+                  arg: pointer,
+                  affinity: cuint) {.
+    importcpp: "#.initThread(@)".}
+
+
+else:
+  when not (defined(macosx) or defined(haiku)):
+    {.passl: "-pthread".}
+
+  when not defined(haiku):
+    {.passc: "-pthread".}
+
+  const
+    schedh = "#define _GNU_SOURCE\n#include <sched.h>"
+    pthreadh* = "#define _GNU_SOURCE\n#include <pthread.h>"
+
+  when not declared(Time):
+    when defined(linux):
+      type Time = clong
+    else:
+      type Time = int
+
+  when (defined(linux) or defined(nintendoswitch)) and defined(amd64):
+    type
+      SysThread* {.importc: "pthread_t",
+                  header: "<sys/types.h>" .} = distinct culong
+      Pthread_attr* {.importc: "pthread_attr_t",
+                    header: "<sys/types.h>".} = object
+        abi: array[56 div sizeof(clong), clong]
+  elif defined(openbsd) and defined(amd64):
+    type
+      SysThread* {.importc: "pthread_t", header: "<pthread.h>".} = object
+      Pthread_attr* {.importc: "pthread_attr_t",
+                       header: "<pthread.h>".} = object
+  else:
+    type
+      SysThread* {.importc: "pthread_t", header: "<sys/types.h>".} = int
+      Pthread_attr* {.importc: "pthread_attr_t",
+                       header: "<sys/types.h>".} = object
+  type
+    Timespec* {.importc: "struct timespec", header: "<time.h>".} = object
+      tv_sec*: Time
+      tv_nsec*: clong
+
+  proc pthread_attr_init*(a1: var Pthread_attr): cint {.
+    importc, header: pthreadh.}
+  proc pthread_attr_setstack*(a1: ptr Pthread_attr, a2: pointer, a3: int): cint {.
+    importc, header: pthreadh.}
+  proc pthread_attr_setstacksize*(a1: var Pthread_attr, a2: int): cint {.
+    importc, header: pthreadh.}
+  proc pthread_attr_destroy*(a1: var Pthread_attr): cint {.
+    importc, header: pthreadh.}
+
+  proc pthread_create*(a1: var SysThread, a2: var Pthread_attr,
+            a3: proc (x: pointer): pointer {.noconv.},
+            a4: pointer): cint {.importc: "pthread_create",
+            header: pthreadh.}
+  proc pthread_join*(a1: SysThread, a2: ptr pointer): cint {.
+    importc, header: pthreadh.}
+
+  proc pthread_cancel*(a1: SysThread): cint {.
+    importc: "pthread_cancel", header: pthreadh.}
+
+  type CpuSet* {.importc: "cpu_set_t", header: schedh.} = object
+     when defined(linux) and defined(amd64):
+       abi: array[1024 div (8 * sizeof(culong)), culong]
+
+  proc cpusetZero*(s: var CpuSet) {.importc: "CPU_ZERO", header: schedh.}
+  proc cpusetIncl*(cpu: cint; s: var CpuSet) {.
+    importc: "CPU_SET", header: schedh.}
+
+  when defined(android):
+    # libc of android doesn't implement pthread_setaffinity_np,
+    # it exposes pthread_gettid_np though, so we can use that in combination
+    # with sched_setaffinity to set the thread affinity.
+    type Pid* {.importc: "pid_t", header: "<sys/types.h>".} = int32 # From posix_other.nim
+
+    proc setAffinityTID*(tid: Pid; setsize: csize_t; s: var CpuSet) {.
+      importc: "sched_setaffinity", header: schedh.}
+
+    proc pthread_gettid_np*(thread: SysThread): Pid {.
+      importc: "pthread_gettid_np", header: pthreadh.}
+
+    proc setAffinity*(thread: SysThread; setsize: csize_t; s: var CpuSet) =
+      setAffinityTID(pthread_gettid_np(thread), setsize, s)
+  else:
+    proc setAffinity*(thread: SysThread; setsize: csize_t; s: var CpuSet) {.
+      importc: "pthread_setaffinity_np", header: pthreadh.}
+
+
+const
+  emulatedThreadVars* = compileOption("tlsEmulation")
+# we preallocate a fixed size for thread local storage, so that no heap
+# allocations are needed. Currently less than 16K are used on a 64bit machine.
+# We use `float` for proper alignment:
+const nimTlsSize {.intdefine.} = 16000
+type
+  ThreadLocalStorage* = array[0..(nimTlsSize div sizeof(float)), float]
+  PGcThread* = ptr GcThread
+  GcThread* {.pure, inheritable.} = object
+    when emulatedThreadVars:
+      tls*: ThreadLocalStorage
+    else:
+      nil
+    when hasSharedHeap:
+      next*, prev*: PGcThread
+      stackBottom*, stackTop*: pointer
+      stackSize*: int
+    else:
+      nil
+
+const hasAllocStack* = defined(zephyr) # maybe freertos too?
+
+type
+  Thread*[TArg] = object
+    core*: PGcThread
+    sys*: SysThread
+    when TArg is void:
+      dataFn*: proc () {.nimcall, gcsafe.}
+    else:
+      dataFn*: proc (m: TArg) {.nimcall, gcsafe.}
+      data*: TArg
+    when hasAllocStack:
+      rawStack*: pointer
+
+proc `=copy`*[TArg](x: var Thread[TArg], y: Thread[TArg]) {.error.}
diff --git a/lib/std/private/underscored_calls.nim b/lib/std/private/underscored_calls.nim
index 6d0a99ab5..f853572b5 100644
--- a/lib/std/private/underscored_calls.nim
+++ b/lib/std/private/underscored_calls.nim
@@ -10,7 +10,9 @@
 
 ## This is an internal helper module. Do not use.
 
-import macros
+import std/macros
+
+proc underscoredCalls*(result, calls, arg0: NimNode)
 
 proc underscoredCall(n, arg0: NimNode): NimNode =
   proc underscorePos(n: NimNode): int =
@@ -19,13 +21,19 @@ proc underscoredCall(n, arg0: NimNode): NimNode =
     return 0
 
   if n.kind in nnkCallKinds:
-    result = copyNimNode(n)
-    result.add n[0]
+    if n[0].kind in {nnkIdent, nnkSym} and n[0].eqIdent("with"):
+      expectKind n[1], {nnkIdent, nnkSym}
 
-    let u = underscorePos(n)
-    for i in 1..u-1: result.add n[i]
-    result.add arg0
-    for i in u+1..n.len-1: result.add n[i]
+      result = newStmtList()
+      underscoredCalls(result, n[2 .. ^1].newStmtList, newDotExpr(arg0, n[1]))
+    else:
+      result = copyNimNode(n)
+      result.add n[0]
+
+      let u = underscorePos(n)
+      for i in 1..u-1: result.add n[i]
+      result.add arg0
+      for i in u+1..n.len-1: result.add n[i]
   elif n.kind in {nnkAsgn, nnkExprEqExpr}:
     var field = n[0]
     if n[0].kind == nnkDotExpr and n[0][0].eqIdent("_"):
@@ -39,7 +47,7 @@ proc underscoredCall(n, arg0: NimNode): NimNode =
     result.add arg0
 
 proc underscoredCalls*(result, calls, arg0: NimNode) =
-  expectKind calls, {nnkArglist, nnkStmtList, nnkStmtListExpr}
+  expectKind calls, {nnkArgList, nnkStmtList, nnkStmtListExpr}
 
   for call in calls:
     if call.kind in {nnkStmtList, nnkStmtListExpr}:
diff --git a/lib/std/private/vmutils.nim b/lib/std/private/vmutils.nim
deleted file mode 100644
index d54977b4e..000000000
--- a/lib/std/private/vmutils.nim
+++ /dev/null
@@ -1,17 +0,0 @@
-template forwardImpl*(impl, arg) {.dirty.} =
-  when sizeof(x) <= 4:
-    when x is SomeSignedInt:
-      impl(cast[uint32](x.int32))
-    else:
-      impl(x.uint32)
-  else:
-    when x is SomeSignedInt:
-      impl(cast[uint64](x.int64))
-    else:
-      impl(x.uint64)
-
-template toUnsigned*(x: int8): uint8 = cast[uint8](x)
-template toUnsigned*(x: int16): uint16 = cast[uint16](x)
-template toUnsigned*(x: int32): uint32 = cast[uint32](x)
-template toUnsigned*(x: int64): uint64 = cast[uint64](x)
-template toUnsigned*(x: int): uint = cast[uint](x)
diff --git a/lib/std/private/win_getsysteminfo.nim b/lib/std/private/win_getsysteminfo.nim
new file mode 100644
index 000000000..b98478231
--- /dev/null
+++ b/lib/std/private/win_getsysteminfo.nim
@@ -0,0 +1,15 @@
+type
+  SystemInfo* = object
+    u1: uint32
+    dwPageSize: uint32
+    lpMinimumApplicationAddress: pointer
+    lpMaximumApplicationAddress: pointer
+    dwActiveProcessorMask: ptr uint32
+    dwNumberOfProcessors*: uint32
+    dwProcessorType: uint32
+    dwAllocationGranularity*: uint32
+    wProcessorLevel: uint16
+    wProcessorRevision: uint16
+
+proc getSystemInfo*(lpSystemInfo: ptr SystemInfo) {.stdcall,
+    dynlib: "kernel32", importc: "GetSystemInfo".}
diff --git a/lib/std/private/win_setenv.nim b/lib/std/private/win_setenv.nim
new file mode 100644
index 000000000..66e199dfe
--- /dev/null
+++ b/lib/std/private/win_setenv.nim
@@ -0,0 +1,106 @@
+#[
+Copyright (c) Facebook, Inc. and its affiliates.
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+    http://www.apache.org/licenses/LICENSE-2.0
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+
+Adapted `setenv` from https://github.com/facebook/folly/blob/master/folly/portability/Stdlib.cpp
+translated from C to nim.
+]#
+
+#[
+Introduced in https://github.com/facebook/folly/commit/5d8ca09a3f96afefb44e35808f03651a096ab9c7
+
+TODO:
+check errno_t vs cint
+]#
+
+when not defined(windows): discard
+else:
+  when defined(nimPreviewSlimSystem):
+    import std/widestrs
+
+  type wchar_t  {.importc: "wchar_t".} = int16
+
+  proc setEnvironmentVariableW*(lpName, lpValue: WideCString): int32 {.
+    stdcall, dynlib: "kernel32", importc: "SetEnvironmentVariableW", sideEffect.}
+    # same as winlean.setEnvironmentVariableA
+
+  proc c_getenv(varname: cstring): cstring {.importc: "getenv", header: "<stdlib.h>".}
+  proc c_wputenv(envstring: ptr wchar_t): cint {.importc: "_wputenv", header: "<stdlib.h>".}
+  proc c_wgetenv(varname: ptr wchar_t): ptr wchar_t {.importc: "_wgetenv", header: "<stdlib.h>".}
+
+  var errno {.importc, header: "<errno.h>".}: cint
+  var genviron {.importc: "_environ".}: ptr ptr char
+    # xxx `ptr UncheckedArray[WideCString]` did not work
+
+  proc wcstombs(wcstr: ptr char, mbstr: ptr wchar_t, count: csize_t): csize_t {.importc, header: "<stdlib.h>".}
+    # xxx cint vs errno_t?
+
+  proc setEnvImpl*(name: string, value: string, overwrite: cint): cint =
+    const EINVAL = cint(22)
+    let wideName: WideCString = newWideCString(name)
+    if overwrite == 0 and c_wgetenv(cast[ptr wchar_t](wideName)) != nil:
+      return 0
+
+    if value != "":
+      let envstring: WideCString = newWideCString(name & "=" & value)
+      let e = c_wputenv(cast[ptr wchar_t](envstring))
+      if e != 0:
+        errno = EINVAL
+        return -1
+      return 0
+    #[
+    We are trying to set the value to an empty string, but `_putenv` deletes
+    entries if the value is an empty string, and just calling
+    SetEnvironmentVariableA doesn't update `_environ`,
+    so we have to do these terrible things.
+    ]#
+    let envstring: WideCString = newWideCString(name & "=  ")
+    if c_wputenv(cast[ptr wchar_t](envstring)) != 0:
+      errno = EINVAL
+      return -1
+    # Here lies the documentation we blatently ignore to make this work.
+    var s = cast[WideCString](c_wgetenv(cast[ptr wchar_t](wideName)))
+    s[0] = Utf16Char('\0')
+    #[
+    This would result in a double null termination, which normally signifies the
+    end of the environment variable list, so we stick a completely empty
+    environment variable into the list instead.
+    ]#
+    s = cast[WideCString](c_wgetenv(cast[ptr wchar_t](wideName)))
+    s[1] = Utf16Char('=')
+    #[
+    If genviron is null, the MBCS environment has not been initialized
+    yet, and we don't need to try to update it. We have to do this otherwise
+    we'd be forcing the initialization and maintenance of the MBCS environment
+    even though it's never actually used in most programs.
+    ]#
+    if genviron != nil:
+
+      # wcstombs returns `high(csize_t)` if any characters cannot be represented
+      # in the current codepage. Skip updating MBCS environment in this case.
+      # For some reason, second `wcstombs` can find non-convertible characters
+      # that the first `wcstombs` cannot.
+      let requiredSizeS = wcstombs(nil, cast[ptr wchar_t](wideName), 0)
+      if requiredSizeS != high(csize_t):
+        let requiredSize = requiredSizeS.int
+        var buf = newSeq[char](requiredSize + 1)
+        let buf2 = buf[0].addr
+        if wcstombs(buf2, cast[ptr wchar_t](wideName), csize_t(requiredSize + 1)) != high(csize_t):
+          var ptrToEnv = c_getenv(cast[cstring](buf2))
+          ptrToEnv[0] = '\0'
+          ptrToEnv = c_getenv(cast[cstring](buf2))
+          ptrToEnv[1] = '='
+
+    # And now, we have to update the outer environment to have a proper empty value.
+    if setEnvironmentVariableW(wideName, value.newWideCString) == 0:
+      errno = EINVAL
+      return -1
+    return 0