diff options
Diffstat (limited to 'lib/pure/random.nim')
| -rw-r--r-- | lib/pure/random.nim | 69 |
1 files changed, 44 insertions, 25 deletions
diff --git a/lib/pure/random.nim b/lib/pure/random.nim index c36ab445b..3ec77d37e 100644 --- a/lib/pure/random.nim +++ b/lib/pure/random.nim @@ -71,23 +71,36 @@ runnableExamples: ## * `list of cryptographic and hashing modules <lib.html#pure-libraries-hashing>`_ ## in the standard library -import algorithm, math -import std/private/since +import std/[algorithm, math] +import std/private/[since, jsutils] when defined(nimPreviewSlimSystem): import std/[assertions] include system/inclrtl {.push debugger: off.} +template whenHasBigInt64(yes64, no64): untyped = + when defined(js): + when compiles(compileOption("jsbigint64")): + when compileOption("jsbigint64"): + yes64 + else: + no64 + else: + no64 + else: + yes64 -when defined(js): - type Ui = uint32 - const randMax = 4_294_967_295u32 -else: +whenHasBigInt64: type Ui = uint64 const randMax = 18_446_744_073_709_551_615u64 +do: + type Ui = uint32 + + const randMax = 4_294_967_295u32 + type Rand* = object ## State of a random number generator. @@ -105,17 +118,17 @@ type ## generator are **not** thread-safe! a0, a1: Ui -when defined(js): - var state = Rand( - a0: 0x69B4C98Cu32, - a1: 0xFED1DD30u32) # global for backwards compatibility -else: +whenHasBigInt64: const DefaultRandSeed = Rand( a0: 0x69B4C98CB8530805u64, a1: 0xFED1DD3004688D67CAu64) # racy for multi-threading but good enough for now: var state = DefaultRandSeed # global for backwards compatibility +do: + var state = Rand( + a0: 0x69B4C98Cu32, + a1: 0xFED1DD30u32) # global for backwards compatibility func isValid(r: Rand): bool {.inline.} = ## Check whether state of `r` is valid. @@ -208,10 +221,10 @@ proc skipRandomNumbers*(s: var Rand) = doAssert vals == [501737, 497901, 500683, 500157] - when defined(js): - const helper = [0xbeac0467u32, 0xd86b048bu32] - else: + whenHasBigInt64: const helper = [0xbeac0467eba5facbu64, 0xd86b048b86aa9922u64] + do: + const helper = [0xbeac0467u32, 0xd86b048bu32] var s0 = Ui 0 s1 = Ui 0 @@ -231,11 +244,14 @@ proc rand[T: uint | uint64](r: var Rand; max: T): T = let max = uint64(max) when T.high.uint64 == uint64.high: if max == uint64.high: return T(next(r)) + var iters = 0 while true: let x = next(r) # avoid `mod` bias - if x <= randMax - (randMax mod max): + if x <= randMax - (randMax mod max) or iters > 20: return T(x mod (max + 1)) + else: + inc iters proc rand*(r: var Rand; max: Natural): int {.benign.} = ## Returns a random integer in the range `0..max` using the given state. @@ -291,7 +307,13 @@ proc rand*(r: var Rand; max: range[0.0 .. high(float)]): float {.benign.} = let x = next(r) when defined(js): - result = (float(x) / float(high(uint32))) * max + when compiles(compileOption("jsbigint64")): + when compileOption("jsbigint64"): + result = (float(x) / float(high(uint64))) * max + else: + result = (float(x) / float(high(uint32))) * max + else: + result = (float(x) / float(high(uint32))) * max else: let u = (0x3FFu64 shl 52u64) or (x shr 12u64) result = (cast[float](u) - 1.0) * max @@ -337,9 +359,9 @@ proc rand*[T: Ordinal or SomeFloat](r: var Rand; x: HSlice[T, T]): T = when T is SomeFloat: result = rand(r, x.b - x.a) + x.a else: # Integers and Enum types - when defined(js): + whenJsNoBigInt64: result = cast[T](rand(r, cast[uint](x.b) - cast[uint](x.a)) + cast[uint](x.a)) - else: + do: result = cast[T](rand(r, cast[uint64](x.b) - cast[uint64](x.a)) + cast[uint64](x.a)) proc rand*[T: Ordinal or SomeFloat](x: HSlice[T, T]): T = @@ -378,14 +400,11 @@ proc rand*[T: Ordinal](r: var Rand; t: typedesc[T]): T {.since: (1, 7, 1).} = when T is range or T is enum: result = rand(r, low(T)..high(T)) elif T is bool: - when defined(js): - result = (r.next or 0) < 0 - else: - result = cast[int64](r.next) < 0 + result = r.next < randMax div 2 else: - when defined(js): + whenJsNoBigInt64: result = cast[T](r.next shr (sizeof(uint)*8 - sizeof(T)*8)) - else: + do: result = cast[T](r.next shr (sizeof(uint64)*8 - sizeof(T)*8)) proc rand*[T: Ordinal](t: typedesc[T]): T = @@ -670,7 +689,7 @@ when not defined(standalone): import std/[hashes, os, sysrand, monotimes] when compileOption("threads"): - import locks + import std/locks var baseSeedLock: Lock baseSeedLock.initLock |