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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:
# .. code-block:: 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): int32 {.inline.} =
return 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 = (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)
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)
let base = result.len
setLen(result, base + 1)
result[base] = '-'
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))
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