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//go:build runtime_memhash_tsip
// This is the tsip hash developed by Damian Gryski, based on ideas from SipHash.
// It is slower than leveldb's hash, but should be "stronger".
// https://en.wikipedia.org/wiki/SipHash
// https://github.com/veorq/SipHash
// https://github.com/dgryski/tsip
package runtime
import (
"internal/binary"
"math/bits"
"unsafe"
)
type sip struct {
v0, v1 uint64
}
func (s *sip) round() {
s.v0 += s.v1
s.v1 = bits.RotateLeft64(s.v1, 13) ^ s.v0
s.v0 = bits.RotateLeft64(s.v0, 35) + s.v1
s.v1 = bits.RotateLeft64(s.v1, 17) ^ s.v0
s.v0 = bits.RotateLeft64(s.v0, 21)
}
func hash64(ptr unsafe.Pointer, n uintptr, seed uintptr) uint64 {
p := unsafe.Slice((*byte)(ptr), n)
k0 := uint64(seed)
k1 := uint64(0)
s := sip{
v0: k0 ^ 0x736f6d6570736575,
v1: k1 ^ 0x646f72616e646f6d,
}
b := uint64(len(p)) << 56
for len(p) >= 8 {
m := binary.LittleEndian.Uint64(p[:8])
s.v1 ^= m
s.round()
s.v0 ^= m
p = p[8:]
}
switch len(p) {
case 7:
b |= uint64(p[6]) << 48
fallthrough
case 6:
b |= uint64(p[5]) << 40
fallthrough
case 5:
b |= uint64(p[4]) << 32
fallthrough
case 4:
b |= uint64(p[3]) << 24
fallthrough
case 3:
b |= uint64(p[2]) << 16
fallthrough
case 2:
b |= uint64(p[1]) << 8
fallthrough
case 1:
b |= uint64(p[0])
}
// last block
s.v1 ^= b
s.round()
s.v0 ^= b
// finalization
s.v1 ^= 0xff
s.round()
s.v1 = bits.RotateLeft64(s.v1, 32)
s.round()
s.v1 = bits.RotateLeft64(s.v1, 32)
return s.v0 ^ s.v1
}
type sip32 struct {
v0, v1 uint32
}
func (s *sip32) round() {
s.v0 += s.v1
s.v1 = bits.RotateLeft32(s.v1, 5) ^ s.v0
s.v0 = bits.RotateLeft32(s.v0, 8) + s.v1
s.v1 = bits.RotateLeft32(s.v1, 13) ^ s.v0
s.v0 = bits.RotateLeft32(s.v0, 7)
}
func hash32(ptr unsafe.Pointer, n uintptr, seed uintptr) uint32 {
p := unsafe.Slice((*byte)(ptr), n)
k0 := uint32(seed)
k1 := uint32(seed >> 32)
s := sip32{
v0: k0 ^ 0x74656462,
v1: k1 ^ 0x6c796765,
}
b := uint32(len(p)) << 24
for len(p) >= 4 {
m := binary.LittleEndian.Uint32(p[:4])
s.v1 ^= m
s.round()
s.v0 ^= m
p = p[4:]
}
switch len(p) {
case 3:
b |= uint32(p[2]) << 16
fallthrough
case 2:
b |= uint32(p[1]) << 8
fallthrough
case 1:
b |= uint32(p[0])
}
// last block
s.v1 ^= b
s.round()
s.v0 ^= b
// finalization
s.v1 ^= 0xff
s.round()
s.v1 = bits.RotateLeft32(s.v1, 16)
s.round()
s.v1 = bits.RotateLeft32(s.v1, 16)
return s.v0 ^ s.v1
}
|
