diff options
author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-28 13:16:40 +0000 |
---|---|---|
committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-28 13:16:40 +0000 |
commit | 47ab3d4a42e9ab51c465c4322d2ec233f6324e6b (patch) | |
tree | a61a0ffd83f4a3def4b36e5c8e99630c559aa723 /src/math/rand/gen_cooked.go | |
parent | Initial commit. (diff) | |
download | golang-1.18-upstream.tar.xz golang-1.18-upstream.zip |
Adding upstream version 1.18.10.upstream/1.18.10upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/math/rand/gen_cooked.go')
-rw-r--r-- | src/math/rand/gen_cooked.go | 89 |
1 files changed, 89 insertions, 0 deletions
diff --git a/src/math/rand/gen_cooked.go b/src/math/rand/gen_cooked.go new file mode 100644 index 0000000..782bb66 --- /dev/null +++ b/src/math/rand/gen_cooked.go @@ -0,0 +1,89 @@ +// Copyright 2009 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +//go:build ignore + +// This program computes the value of rngCooked in rng.go, +// which is used for seeding all instances of rand.Source. +// a 64bit and a 63bit version of the array is printed to +// the standard output. + +package main + +import "fmt" + +const ( + length = 607 + tap = 273 + mask = (1 << 63) - 1 + a = 48271 + m = (1 << 31) - 1 + q = 44488 + r = 3399 +) + +var ( + rngVec [length]int64 + rngTap, rngFeed int +) + +func seedrand(x int32) int32 { + hi := x / q + lo := x % q + x = a*lo - r*hi + if x < 0 { + x += m + } + return x +} + +func srand(seed int32) { + rngTap = 0 + rngFeed = length - tap + seed %= m + if seed < 0 { + seed += m + } else if seed == 0 { + seed = 89482311 + } + x := seed + for i := -20; i < length; i++ { + x = seedrand(x) + if i >= 0 { + var u int64 + u = int64(x) << 20 + x = seedrand(x) + u ^= int64(x) << 10 + x = seedrand(x) + u ^= int64(x) + rngVec[i] = u + } + } +} + +func vrand() int64 { + rngTap-- + if rngTap < 0 { + rngTap += length + } + rngFeed-- + if rngFeed < 0 { + rngFeed += length + } + x := (rngVec[rngFeed] + rngVec[rngTap]) + rngVec[rngFeed] = x + return x +} + +func main() { + srand(1) + for i := uint64(0); i < 7.8e12; i++ { + vrand() + } + fmt.Printf("rngVec after 7.8e12 calls to vrand:\n%#v\n", rngVec) + for i := range rngVec { + rngVec[i] &= mask + } + fmt.Printf("lower 63bit of rngVec after 7.8e12 calls to vrand:\n%#v\n", rngVec) +} |