mirror of
https://github.com/autc04/Retro68.git
synced 2024-11-30 19:53:46 +00:00
90 lines
1.5 KiB
Go
90 lines
1.5 KiB
Go
// 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.
|
|
|
|
// +build ignore
|
|
|
|
// This program computes the value of rng_cooked 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)
|
|
}
|