libgo/go/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
   8 // http://en.wikipedia.org/wiki/Fowler%E2%80%93Noll%E2%80%93Vo_hash_function.
   9 package fnv
  10
  11 import (
  12         "hash"
  13 )
  14
  15 type (
  16         sum32  uint32
  17         sum32a uint32
  18         sum64  uint64
  19         sum64a uint64
  20 )
  21
  22 const (
  23         offset32 = 2166136261
  24         offset64 = 14695981039346656037
  25         prime32  = 16777619
  26         prime64  = 1099511628211
  27 )
  28
  29 // New32 returns a new 32-bit FNV-1 hash.Hash.
  30 func New32() hash.Hash32 {
  31         var s sum32 = offset32
  32         return &s
  33 }
  34
  35 // New32a returns a new 32-bit FNV-1a hash.Hash.
  36 func New32a() hash.Hash32 {
  37         var s sum32a = offset32
  38         return &s
  39 }
  40
  41 // New64 returns a new 64-bit FNV-1 hash.Hash.
  42 func New64() hash.Hash64 {
  43         var s sum64 = offset64
  44         return &s
  45 }
  46
  47 // New64a returns a new 64-bit FNV-1a hash.Hash.
  48 func New64a() hash.Hash64 {
  49         var s sum64a = offset64
  50         return &s
  51 }
  52
  53 func (s *sum32) Reset()  { *s = offset32 }
  54 func (s *sum32a) Reset() { *s = offset32 }
  55 func (s *sum64) Reset()  { *s = offset64 }
  56 func (s *sum64a) Reset() { *s = offset64 }
  57
  58 func (s *sum32) Sum32() uint32  { return uint32(*s) }
  59 func (s *sum32a) Sum32() uint32 { return uint32(*s) }
  60 func (s *sum64) Sum64() uint64  { return uint64(*s) }
  61 func (s *sum64a) Sum64() uint64 { return uint64(*s) }
  62
  63 func (s *sum32) Write(data []byte) (int, error) {
  64         hash := *s
  65         for _, c := range data {
  66                 hash *= prime32
  67                 hash ^= sum32(c)
  68         }
  69         *s = hash
  70         return len(data), nil
  71 }
  72
  73 func (s *sum32a) Write(data []byte) (int, error) {
  74         hash := *s
  75         for _, c := range data {
  76                 hash ^= sum32a(c)
  77                 hash *= prime32
  78         }
  79         *s = hash
  80         return len(data), nil
  81 }
  82
  83 func (s *sum64) Write(data []byte) (int, error) {
  84         hash := *s
  85         for _, c := range data {
  86                 hash *= prime64
  87                 hash ^= sum64(c)
  88         }
  89         *s = hash
  90         return len(data), nil
  91 }
  92
  93 func (s *sum64a) Write(data []byte) (int, error) {
  94         hash := *s
  95         for _, c := range data {
  96                 hash ^= sum64a(c)
  97                 hash *= prime64
  98         }
  99         *s = hash
 100         return len(data), nil
 101 }
 102
 103 func (s *sum32) Size() int  { return 4 }
 104 func (s *sum32a) Size() int { return 4 }
 105 func (s *sum64) Size() int  { return 8 }
 106 func (s *sum64a) Size() int { return 8 }
 107
 108 func (s *sum32) BlockSize() int  { return 1 }
 109 func (s *sum32a) BlockSize() int { return 1 }
 110 func (s *sum64) BlockSize() int  { return 1 }
 111 func (s *sum64a) BlockSize() int { return 1 }
 112
 113 func (s *sum32) Sum(in []byte) []byte {
 114         v := uint32(*s)
 115         return append(in, byte(v>>24), byte(v>>16), byte(v>>8), byte(v))
 116 }
 117
 118 func (s *sum32a) Sum(in []byte) []byte {
 119         v := uint32(*s)
 120         return append(in, byte(v>>24), byte(v>>16), byte(v>>8), byte(v))
 121 }
 122
 123 func (s *sum64) Sum(in []byte) []byte {
 124         v := uint64(*s)
 125         return append(in, byte(v>>56), byte(v>>48), byte(v>>40), byte(v>>32), byte(v>>24), byte(v>>16), byte(v>>8), byte(v))
 126 }
 127
 128 func (s *sum64a) Sum(in []byte) []byte {
 129         v := uint64(*s)
 130         return append(in, byte(v>>56), byte(v>>48), byte(v>>40), byte(v>>32), byte(v>>24), byte(v>>16), byte(v>>8), byte(v))
 131 }