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murmur128.go
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murmur128.go
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package murmur3
import (
"math/bits"
"reflect"
"unsafe"
)
func New128() *MurmurHash128 {
return New128WithSeed(0)
}
func New128WithSeed(seed int) *MurmurHash128 {
h := &MurmurHash128{}
h.seed = seed
return h
}
type MurmurHash128 struct {
MurmurHash
}
func (h *MurmurHash128) HashInt(i int) *BytesHashCode {
if bits.UintSize == 32 {
return h.HashInt32(int32(i))
}
return h.HashInt64(int64(i))
}
func (h *MurmurHash128) HashInt32(i int32) *BytesHashCode {
return h.make([]byte{byte(i), byte(i >> 8), byte(i >> 16), byte(i >> 24)})
}
func (h *MurmurHash128) HashInt64(i int64) *BytesHashCode {
return h.make([]byte{
byte(i), byte(i >> 8), byte(i >> 16), byte(i >> 24),
byte(i >> 32), byte(i >> 40), byte(i >> 48), byte(i >> 56)})
}
func (h *MurmurHash128) HashString(s string) *BytesHashCode {
sh := (*reflect.StringHeader)(unsafe.Pointer(&s))
bh := reflect.SliceHeader{Data: sh.Data, Len: sh.Len, Cap: sh.Len}
return h.HashBytes(*(*[]byte)(unsafe.Pointer(&bh)))
}
func (h *MurmurHash128) HashBytes(bytes []byte) *BytesHashCode {
return h.make(bytes)
}
func (h *MurmurHash128) HashBytesWithOffset(bytes []byte, offset, length int) *BytesHashCode {
return h.make(bytes[offset : offset+length])
}
func (h *MurmurHash128) make(bytes []byte) *BytesHashCode {
length := uint64(len(bytes))
h1, h2, buffer := h.bmix(uint64(h.seed), uint64(h.seed), bytes)
var k1, k2 uint64
switch len(buffer) & 15 {
case 15:
k2 ^= uint64(buffer[14]) << 48
fallthrough
case 14:
k2 ^= uint64(buffer[13]) << 40
fallthrough
case 13:
k2 ^= uint64(buffer[12]) << 32
fallthrough
case 12:
k2 ^= uint64(buffer[11]) << 24
fallthrough
case 11:
k2 ^= uint64(buffer[10]) << 16
fallthrough
case 10:
k2 ^= uint64(buffer[9]) << 8
fallthrough
case 9:
k2 ^= uint64(buffer[8])
fallthrough
case 8:
k1 ^= uint64(buffer[7]) << 56
fallthrough
case 7:
k1 ^= uint64(buffer[6]) << 48
fallthrough
case 6:
k1 ^= uint64(buffer[5]) << 40
fallthrough
case 5:
k1 ^= uint64(buffer[4]) << 32
fallthrough
case 4:
k1 ^= uint64(buffer[3]) << 24
fallthrough
case 3:
k1 ^= uint64(buffer[2]) << 16
fallthrough
case 2:
k1 ^= uint64(buffer[1]) << 8
fallthrough
case 1:
k1 ^= uint64(buffer[0])
}
h1 ^= h.mixK1(k1)
h2 ^= h.mixK2(k2)
h1 ^= length
h2 ^= length
h1 += h2
h2 += h1
h1 = h.fmix(h1)
h2 = h.fmix(h2)
h1 += h2
h2 += h1
return h.makeHash(h1, h2)
}
func (h *MurmurHash128) mixK1(k1 uint64) uint64 {
k1 *= 0x87c37b91114253d5
k1 = bits.RotateLeft64(k1, 31)
k1 *= 0x4cf5ad432745937f
return k1
}
func (h *MurmurHash128) mixK2(k2 uint64) uint64 {
k2 *= 0x4cf5ad432745937f
k2 = bits.RotateLeft64(k2, 33)
k2 *= 0x87c37b91114253d5
return k2
}
func (h *MurmurHash128) bmix(h1, h2 uint64, bytes []byte) (uint64, uint64, []byte) {
blocks := len(bytes) / 16
for i := 0; i < blocks; i++ {
t := (*[2]uint64)(unsafe.Pointer(&bytes[i*16]))
k1, k2 := t[0], t[1]
h1 ^= h.mixK1(k1)
h1 = bits.RotateLeft64(h1, 27)
h1 += h2
h1 = h1*5 + 0x52dce729
h2 ^= h.mixK2(k2)
h2 = bits.RotateLeft64(h2, 31)
h2 += h1
h2 = h2*5 + 0x38495ab5
}
return h1, h2, bytes[blocks*16:]
}
func (h *MurmurHash128) fmix(k uint64) uint64 {
k ^= k >> 33
k *= 0xff51afd7ed558ccd
k ^= k >> 33
k *= 0xc4ceb9fe1a85ec53
k ^= k >> 33
return k
}
func (h *MurmurHash128) makeHash(h1, h2 uint64) *BytesHashCode {
return &BytesHashCode{[]byte{
byte(h1 >> 0), byte(h1 >> 8), byte(h1 >> 16), byte(h1 >> 24),
byte(h1 >> 32), byte(h1 >> 40), byte(h1 >> 48), byte(h1 >> 56),
byte(h2 >> 0), byte(h2 >> 8), byte(h2 >> 16), byte(h2 >> 24),
byte(h2 >> 32), byte(h2 >> 40), byte(h2 >> 48), byte(h2 >> 56)}}
}