73 lines
1.6 KiB
Go
73 lines
1.6 KiB
Go
// Copyright 2013, Sébastien Paolacci. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style
|
|
// license that can be found in the LICENSE file.
|
|
|
|
// Package murmur3 provides an amd64 native (Go generic fallback)
|
|
// implementation of the murmur3 hash algorithm for strings and slices.
|
|
//
|
|
// Assembly is provided for amd64 go1.5+; pull requests are welcome for other
|
|
// architectures.
|
|
package murmur3
|
|
|
|
import (
|
|
"reflect"
|
|
"unsafe"
|
|
)
|
|
|
|
type bmixer interface {
|
|
bmix(p []byte) (tail []byte)
|
|
Size() (n int)
|
|
reset()
|
|
}
|
|
|
|
type digest struct {
|
|
clen int // Digested input cumulative length.
|
|
tail []byte // 0 to Size()-1 bytes view of `buf'.
|
|
buf [16]byte // Expected (but not required) to be Size() large.
|
|
bmixer
|
|
}
|
|
|
|
func (d *digest) BlockSize() int { return 1 }
|
|
|
|
func (d *digest) Write(p []byte) (n int, err error) {
|
|
n = len(p)
|
|
d.clen += n
|
|
|
|
if len(d.tail) > 0 {
|
|
// Stick back pending bytes.
|
|
nfree := d.Size() - len(d.tail) // nfree ∈ [1, d.Size()-1].
|
|
if nfree < len(p) {
|
|
// One full block can be formed.
|
|
block := append(d.tail, p[:nfree]...)
|
|
p = p[nfree:]
|
|
_ = d.bmix(block) // No tail.
|
|
} else {
|
|
// Tail's buf is large enough to prevent reallocs.
|
|
p = append(d.tail, p...)
|
|
}
|
|
}
|
|
|
|
d.tail = d.bmix(p)
|
|
|
|
// Keep own copy of the 0 to Size()-1 pending bytes.
|
|
nn := copy(d.buf[:], d.tail)
|
|
d.tail = d.buf[:nn]
|
|
|
|
return n, nil
|
|
}
|
|
|
|
func (d *digest) Reset() {
|
|
d.clen = 0
|
|
d.tail = nil
|
|
d.bmixer.reset()
|
|
}
|
|
|
|
func strslice(slice []byte) string {
|
|
var str string
|
|
*(*reflect.StringHeader)(unsafe.Pointer(&str)) = reflect.StringHeader{
|
|
Data: ((*reflect.SliceHeader)(unsafe.Pointer(&slice))).Data,
|
|
Len: len(slice),
|
|
}
|
|
return str
|
|
}
|