85 lines
1.6 KiB
Go
85 lines
1.6 KiB
Go
package gen
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import (
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"crypto/md5"
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"encoding/binary"
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)
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func rotl64(x uint64, b uint8) uint64 {
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return (x << b) | (x >> (64 - b))
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}
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type Xoroshiro struct {
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L uint64
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H uint64
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}
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func (x *Xoroshiro) Next() uint64 {
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l := x.L
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h := x.H
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n := rotl64(l+h, 17) + l
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h ^= l
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x.L = rotl64(l, 49) ^ h ^ (h << 21)
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x.H = rotl64(h, 28)
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return n
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}
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func (x *Xoroshiro) NextBound(n uint32) int32 {
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r := (x.Next() & 0xFFFFFFFF) * uint64(n)
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if uint32(r) < n {
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for uint32(r) < (^n+1)%n {
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r = (x.Next() & 0xFFFFFFFF) * uint64(n)
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}
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}
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return int32(r >> 32)
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}
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func (x *Xoroshiro) NextFloat() float32 {
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return float32(x.Next()>>(64-24)) * 5.9604645e-8
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}
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func (x *Xoroshiro) NextFloat64() float64 {
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return float64(x.Next()>>(64-53)) * 1.1102230246251565e-16
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}
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// XoroshiroFromString creates an Xoroshiro from an MD5 hash of the given string.
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func XoroshiroFromString(s string) (x Xoroshiro) {
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sum := md5.Sum([]byte(s))
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x.L = binary.BigEndian.Uint64(sum[:8])
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x.H = binary.BigEndian.Uint64(sum[8:])
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return
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}
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// XoroshiroFromSeed creates an Xoroshiro from an int64 seed.
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func XoroshiroFromSeed(seed int64) (x Xoroshiro) {
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x.L = uint64(seed) ^ 0x6a09e667f3bcc909
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x.H = x.L + 0x9e3779b97f4a7c15
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return
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}
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func mixStafford13(s uint64) uint64 {
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s = (s ^ (s >> 30)) * 0xbf58476d1ce4e5b9
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s = (s ^ (s >> 27)) * 0x94d049bb133111eb
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return s ^ (s >> 31)
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}
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func (x *Xoroshiro) Mix() {
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x.L = mixStafford13(x.L)
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x.H = mixStafford13(x.H)
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}
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func (x *Xoroshiro) Xor(x2 Xoroshiro) {
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x.L ^= x2.L
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x.H ^= x2.H
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}
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func (x *Xoroshiro) XorString(s string) {
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x.Xor(XoroshiroFromString(s))
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}
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func (x *Xoroshiro) Split() (x2 Xoroshiro) {
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x2.L = x.Next()
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x2.H = x.Next()
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return
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}
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