sing-box/transport/clashssr/tools/random.go

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package tools
import (
"encoding/binary"
"github.com/Dreamacro/clash/common/pool"
)
// XorShift128Plus - a pseudorandom number generator
type XorShift128Plus struct {
s [2]uint64
}
func (r *XorShift128Plus) Next() uint64 {
x := r.s[0]
y := r.s[1]
r.s[0] = y
x ^= x << 23
x ^= y ^ (x >> 17) ^ (y >> 26)
r.s[1] = x
return x + y
}
func (r *XorShift128Plus) InitFromBin(bin []byte) {
var full []byte
if len(bin) < 16 {
full := pool.Get(16)[:0]
defer pool.Put(full)
full = append(full, bin...)
for len(full) < 16 {
full = append(full, 0)
}
} else {
full = bin
}
r.s[0] = binary.LittleEndian.Uint64(full[:8])
r.s[1] = binary.LittleEndian.Uint64(full[8:16])
}
func (r *XorShift128Plus) InitFromBinAndLength(bin []byte, length int) {
var full []byte
if len(bin) < 16 {
full := pool.Get(16)[:0]
defer pool.Put(full)
full = append(full, bin...)
for len(full) < 16 {
full = append(full, 0)
}
}
full = bin
binary.LittleEndian.PutUint16(full, uint16(length))
r.s[0] = binary.LittleEndian.Uint64(full[:8])
r.s[1] = binary.LittleEndian.Uint64(full[8:16])
for i := 0; i < 4; i++ {
r.Next()
}
}