├── README.md
├── license.txt
├── murmur_test.go
└── murmur.go


/README.md:
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1 | murmur
2 | ======
3 | 
4 | Go Murmur3 hash implementation
5 | 
6 | Based on
7 | 
8 | http://en.wikipedia.org/wiki/MurmurHash
9 | 


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/license.txt:
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 1 | Copyright 2013 Hui Chen
 2 | 
 3 | Licensed under the Apache License, Version 2.0 (the "License");
 4 | you may not use this file except in compliance with the License.
 5 | You may obtain a copy of the License at
 6 | 
 7 |     http://www.apache.org/licenses/LICENSE-2.0
 8 | 
 9 | Unless required by applicable law or agreed to in writing, software
10 | distributed under the License is distributed on an "AS IS" BASIS,
11 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 | See the License for the specific language governing permissions and
13 | limitations under the License.
14 | 


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/murmur_test.go:
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 1 | package murmur
 2 | 
 3 | import (
 4 | 	"testing"
 5 | )
 6 | 
 7 | func TestMurmur3(t *testing.T) {
 8 | 	text1 := []byte("The quick brown fox jumps over the lazy dog")
 9 | 	expectedHash1 := uint32(0x78e69e27)
10 | 	actualHash1 := Murmur3(text1)
11 | 	if expectedHash1 != actualHash1 {
12 | 		t.Errorf("Expected hash value: %d, got %d", expectedHash1, actualHash1)
13 | 	}
14 | 
15 | 	text2 := []byte("The quick brown fox jumps over the lazy cog")
16 | 	expectedHash2 := uint32(0xd5ece287)
17 | 	actualHash2 := Murmur3(text2)
18 | 	if expectedHash2 != actualHash2 {
19 | 		t.Errorf("Expected hash value: %d, got %d", expectedHash2, actualHash2)
20 | 	}
21 | }
22 | 


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/murmur.go:
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 1 | // Murmur3 32bit hash function based on
 2 | // http://en.wikipedia.org/wiki/MurmurHash
 3 | package murmur
 4 | 
 5 | const (
 6 | 	c1 = 0xcc9e2d51
 7 | 	c2 = 0x1b873593
 8 | 	c3 = 0x85ebca6b
 9 | 	c4 = 0xc2b2ae35
10 | 	r1 = 15
11 | 	r2 = 13
12 | 	m  = 5
13 | 	n  = 0xe6546b64
14 | )
15 | 
16 | var (
17 | 	Seed = uint32(1)
18 | )
19 | 
20 | func Murmur3(key []byte) (hash uint32) {
21 | 	hash = Seed
22 | 	iByte := 0
23 | 	for ; iByte+4 <= len(key); iByte += 4 {
24 | 		k := uint32(key[iByte]) | uint32(key[iByte+1])<<8 | uint32(key[iByte+2])<<16 | uint32(key[iByte+3])<<24
25 | 		k *= c1
26 | 		k = (k << r1) | (k >> (32 - r1))
27 | 		k *= c2
28 | 		hash ^= k
29 | 		hash = (hash << r2) | (hash >> (32 - r2))
30 | 		hash = hash*m + n
31 | 	}
32 | 
33 | 	var remainingBytes uint32
34 | 	switch len(key) - iByte {
35 | 	case 3:
36 | 		remainingBytes += uint32(key[iByte+2]) << 16
37 | 		fallthrough
38 | 	case 2:
39 | 		remainingBytes += uint32(key[iByte+1]) << 8
40 | 		fallthrough
41 | 	case 1:
42 | 		remainingBytes += uint32(key[iByte])
43 | 		remainingBytes *= c1
44 | 		remainingBytes = (remainingBytes << r1) | (remainingBytes >> (32 - r1))
45 | 		remainingBytes = remainingBytes * c2
46 | 		hash ^= remainingBytes
47 | 	}
48 | 
49 | 	hash ^= uint32(len(key))
50 | 	hash ^= hash >> 16
51 | 	hash *= c3
52 | 	hash ^= hash >> 13
53 | 	hash *= c4
54 | 	hash ^= hash >> 16
55 | 	
56 | 	// 出发吧，狗嬷嬷！
57 | 	return
58 | }
59 | 


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