forked from gitea/gitea
49 lines
853 B
Go
49 lines
853 B
Go
|
// Copyright (c) 2012, Suryandaru Triandana <syndtr@gmail.com>
|
||
|
|
// All rights reserved.
|
||
|
|
//
|
||
|
|
// Use of this source code is governed by a BSD-style license that can be
|
||
|
|
// found in the LICENSE file.
|
||
|
|
|
||
|
|
package util
|
||
|
|
|
||
|
|
import (
|
||
|
|
"bytes"
|
||
|
|
"encoding/binary"
|
||
|
|
)
|
||
|
|
|
||
|
|
// Hash return hash of the given data.
|
||
|
|
func Hash(data []byte, seed uint32) uint32 {
|
||
|
|
// Similar to murmur hash
|
||
|
|
var m uint32 = 0xc6a4a793
|
||
|
|
var r uint32 = 24
|
||
|
|
h := seed ^ (uint32(len(data)) * m)
|
||
|
|
|
||
|
|
buf := bytes.NewBuffer(data)
|
||
|
|
for buf.Len() >= 4 {
|
||
|
|
var w uint32
|
||
|
|
binary.Read(buf, binary.LittleEndian, &w)
|
||
|
|
h += w
|
||
|
|
h *= m
|
||
|
|
h ^= (h >> 16)
|
||
|
|
}
|
||
|
|
|
||
|
|
rest := buf.Bytes()
|
||
|
|
switch len(rest) {
|
||
|
|
default:
|
||
|
|
panic("not reached")
|
||
|
|
case 3:
|
||
|
|
h += uint32(rest[2]) << 16
|
||
|
|
fallthrough
|
||
|
|
case 2:
|
||
|
|
h += uint32(rest[1]) << 8
|
||
|
|
fallthrough
|
||
|
|
case 1:
|
||
|
|
h += uint32(rest[0])
|
||
|
|
h *= m
|
||
|
|
h ^= (h >> r)
|
||
|
|
case 0:
|
||
|
|
}
|
||
|
|
|
||
|
|
return h
|
||
|
|
}
|