Source file src/pkg/hash/fnv/fnv.go
1 // Copyright 2011 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 // Package fnv implements FNV-1 and FNV-1a, non-cryptographic hash functions 6 // created by Glenn Fowler, Landon Curt Noll, and Phong Vo. 7 // See http://isthe.com/chongo/tech/comp/fnv/. 8 package fnv 9 10 import ( 11 "hash" 12 ) 13 14 type ( 15 sum32 uint32 16 sum32a uint32 17 sum64 uint64 18 sum64a uint64 19 ) 20 21 const ( 22 offset32 = 2166136261 23 offset64 = 14695981039346656037 24 prime32 = 16777619 25 prime64 = 1099511628211 26 ) 27 28 // New32 returns a new 32-bit FNV-1 hash.Hash. 29 func New32() hash.Hash32 { 30 var s sum32 = offset32 31 return &s 32 } 33 34 // New32a returns a new 32-bit FNV-1a hash.Hash. 35 func New32a() hash.Hash32 { 36 var s sum32a = offset32 37 return &s 38 } 39 40 // New64 returns a new 64-bit FNV-1 hash.Hash. 41 func New64() hash.Hash64 { 42 var s sum64 = offset64 43 return &s 44 } 45 46 // New64a returns a new 64-bit FNV-1a hash.Hash. 47 func New64a() hash.Hash64 { 48 var s sum64a = offset64 49 return &s 50 } 51 52 func (s *sum32) Reset() { *s = offset32 } 53 func (s *sum32a) Reset() { *s = offset32 } 54 func (s *sum64) Reset() { *s = offset64 } 55 func (s *sum64a) Reset() { *s = offset64 } 56 57 func (s *sum32) Sum32() uint32 { return uint32(*s) } 58 func (s *sum32a) Sum32() uint32 { return uint32(*s) } 59 func (s *sum64) Sum64() uint64 { return uint64(*s) } 60 func (s *sum64a) Sum64() uint64 { return uint64(*s) } 61 62 func (s *sum32) Write(data []byte) (int, error) { 63 hash := *s 64 for _, c := range data { 65 hash *= prime32 66 hash ^= sum32(c) 67 } 68 *s = hash 69 return len(data), nil 70 } 71 72 func (s *sum32a) Write(data []byte) (int, error) { 73 hash := *s 74 for _, c := range data { 75 hash ^= sum32a(c) 76 hash *= prime32 77 } 78 *s = hash 79 return len(data), nil 80 } 81 82 func (s *sum64) Write(data []byte) (int, error) { 83 hash := *s 84 for _, c := range data { 85 hash *= prime64 86 hash ^= sum64(c) 87 } 88 *s = hash 89 return len(data), nil 90 } 91 92 func (s *sum64a) Write(data []byte) (int, error) { 93 hash := *s 94 for _, c := range data { 95 hash ^= sum64a(c) 96 hash *= prime64 97 } 98 *s = hash 99 return len(data), nil 100 } 101 102 func (s *sum32) Size() int { return 4 } 103 func (s *sum32a) Size() int { return 4 } 104 func (s *sum64) Size() int { return 8 } 105 func (s *sum64a) Size() int { return 8 } 106 107 func (s *sum32) BlockSize() int { return 1 } 108 func (s *sum32a) BlockSize() int { return 1 } 109 func (s *sum64) BlockSize() int { return 1 } 110 func (s *sum64a) BlockSize() int { return 1 } 111 112 func (s *sum32) Sum(in []byte) []byte { 113 v := uint32(*s) 114 in = append(in, byte(v>>24)) 115 in = append(in, byte(v>>16)) 116 in = append(in, byte(v>>8)) 117 in = append(in, byte(v)) 118 return in 119 } 120 121 func (s *sum32a) Sum(in []byte) []byte { 122 v := uint32(*s) 123 in = append(in, byte(v>>24)) 124 in = append(in, byte(v>>16)) 125 in = append(in, byte(v>>8)) 126 in = append(in, byte(v)) 127 return in 128 } 129 130 func (s *sum64) Sum(in []byte) []byte { 131 v := uint64(*s) 132 in = append(in, byte(v>>56)) 133 in = append(in, byte(v>>48)) 134 in = append(in, byte(v>>40)) 135 in = append(in, byte(v>>32)) 136 in = append(in, byte(v>>24)) 137 in = append(in, byte(v>>16)) 138 in = append(in, byte(v>>8)) 139 in = append(in, byte(v)) 140 return in 141 } 142 143 func (s *sum64a) Sum(in []byte) []byte { 144 v := uint64(*s) 145 in = append(in, byte(v>>56)) 146 in = append(in, byte(v>>48)) 147 in = append(in, byte(v>>40)) 148 in = append(in, byte(v>>32)) 149 in = append(in, byte(v>>24)) 150 in = append(in, byte(v>>16)) 151 in = append(in, byte(v>>8)) 152 in = append(in, byte(v)) 153 return in 154 }