149 lines
2.7 KiB
Go
149 lines
2.7 KiB
Go
package murmur3
|
|
|
|
// https://github.com/spaolacci/murmur3/blob/master/murmur32.go
|
|
|
|
import (
|
|
"hash"
|
|
"unsafe"
|
|
)
|
|
|
|
// Make sure interfaces are correctly implemented.
|
|
var (
|
|
_ hash.Hash32 = new(digest32)
|
|
_ bmixer = new(digest32)
|
|
)
|
|
|
|
const (
|
|
c1_32 uint32 = 0xcc9e2d51
|
|
c2_32 uint32 = 0x1b873593
|
|
)
|
|
|
|
// digest32 represents a partial evaluation of a 32 bites hash.
|
|
type digest32 struct {
|
|
digest
|
|
h1 uint32 // Unfinalized running hash.
|
|
}
|
|
|
|
// New32 returns new 32-bit hasher
|
|
func New32() hash.Hash32 { return New32WithSeed(0) }
|
|
|
|
// New32WithSeed returns new 32-bit hasher set with explicit seed value
|
|
func New32WithSeed(seed uint32) hash.Hash32 {
|
|
d := new(digest32)
|
|
d.seed = seed
|
|
d.bmixer = d
|
|
d.Reset()
|
|
return d
|
|
}
|
|
|
|
func (d *digest32) Size() int { return 4 }
|
|
|
|
func (d *digest32) reset() { d.h1 = d.seed }
|
|
|
|
func (d *digest32) Sum(b []byte) []byte {
|
|
h := d.Sum32()
|
|
return append(b, byte(h>>24), byte(h>>16), byte(h>>8), byte(h))
|
|
}
|
|
|
|
// Digest as many blocks as possible.
|
|
func (d *digest32) bmix(p []byte) (tail []byte) {
|
|
h1 := d.h1
|
|
|
|
nblocks := len(p) / 4
|
|
for i := 0; i < nblocks; i++ {
|
|
k1 := *(*uint32)(unsafe.Pointer(&p[i*4]))
|
|
|
|
k1 *= c1_32
|
|
k1 = (k1 << 15) | (k1 >> 17) // rotl32(k1, 15)
|
|
k1 *= c2_32
|
|
|
|
h1 ^= k1
|
|
h1 = (h1 << 13) | (h1 >> 19) // rotl32(h1, 13)
|
|
h1 = h1*4 + h1 + 0xe6546b64
|
|
}
|
|
d.h1 = h1
|
|
return p[nblocks*d.Size():]
|
|
}
|
|
|
|
func (d *digest32) Sum32() (h1 uint32) {
|
|
|
|
h1 = d.h1
|
|
|
|
var k1 uint32
|
|
switch len(d.tail) & 3 {
|
|
case 3:
|
|
k1 ^= uint32(d.tail[2]) << 16
|
|
fallthrough
|
|
case 2:
|
|
k1 ^= uint32(d.tail[1]) << 8
|
|
fallthrough
|
|
case 1:
|
|
k1 ^= uint32(d.tail[0])
|
|
k1 *= c1_32
|
|
k1 = (k1 << 15) | (k1 >> 17) // rotl32(k1, 15)
|
|
k1 *= c2_32
|
|
h1 ^= k1
|
|
}
|
|
|
|
h1 ^= uint32(d.clen)
|
|
|
|
h1 ^= h1 >> 16
|
|
h1 *= 0x85ebca6b
|
|
h1 ^= h1 >> 13
|
|
h1 *= 0xc2b2ae35
|
|
h1 ^= h1 >> 16
|
|
|
|
return h1
|
|
}
|
|
|
|
func Sum32(data []byte) uint32 { return Sum32WithSeed(data, 0) }
|
|
|
|
func Sum32WithSeed(data []byte, seed uint32) uint32 {
|
|
h1 := seed
|
|
|
|
nblocks := len(data) / 4
|
|
var p uintptr
|
|
if len(data) > 0 {
|
|
p = uintptr(unsafe.Pointer(&data[0]))
|
|
}
|
|
p1 := p + uintptr(4*nblocks)
|
|
for ; p < p1; p += 4 {
|
|
k1 := *(*uint32)(unsafe.Pointer(p))
|
|
|
|
k1 *= c1_32
|
|
k1 = (k1 << 15) | (k1 >> 17) // rotl32(k1, 15)
|
|
k1 *= c2_32
|
|
|
|
h1 ^= k1
|
|
h1 = (h1 << 13) | (h1 >> 19) // rotl32(h1, 13)
|
|
h1 = h1*4 + h1 + 0xe6546b64
|
|
}
|
|
|
|
tail := data[nblocks*4:]
|
|
|
|
var k1 uint32
|
|
switch len(tail) & 3 {
|
|
case 3:
|
|
k1 ^= uint32(tail[2]) << 16
|
|
fallthrough
|
|
case 2:
|
|
k1 ^= uint32(tail[1]) << 8
|
|
fallthrough
|
|
case 1:
|
|
k1 ^= uint32(tail[0])
|
|
k1 *= c1_32
|
|
k1 = (k1 << 15) | (k1 >> 17) // rotl32(k1, 15)
|
|
k1 *= c2_32
|
|
h1 ^= k1
|
|
}
|
|
|
|
h1 ^= uint32(len(data))
|
|
|
|
h1 ^= h1 >> 16
|
|
h1 *= 0x85ebca6b
|
|
h1 ^= h1 >> 13
|
|
h1 *= 0xc2b2ae35
|
|
h1 ^= h1 >> 16
|
|
|
|
return h1
|
|
}
|