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 // https://en.wikipedia.org/wiki/Fowler-Noll-Vo_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 // Its Sum method will lay the value out in big-endian byte order.
  31 func New32() hash.Hash32 {
  32         var s sum32 = offset32
  33         return &s
  34 }
  35
  36 // New32a returns a new 32-bit FNV-1a hash.Hash.
  37 // Its Sum method will lay the value out in big-endian byte order.
  38 func New32a() hash.Hash32 {
  39         var s sum32a = offset32
  40         return &s
  41 }
  42
  43 // New64 returns a new 64-bit FNV-1 hash.Hash.
  44 // Its Sum method will lay the value out in big-endian byte order.
  45 func New64() hash.Hash64 {
  46         var s sum64 = offset64
  47         return &s
  48 }
  49
  50 // New64a returns a new 64-bit FNV-1a hash.Hash.
  51 // Its Sum method will lay the value out in big-endian byte order.
  52 func New64a() hash.Hash64 {
  53         var s sum64a = offset64
  54         return &s
  55 }
  56
  57 func (s *sum32) Reset()  { *s = offset32 }
  58 func (s *sum32a) Reset() { *s = offset32 }
  59 func (s *sum64) Reset()  { *s = offset64 }
  60 func (s *sum64a) Reset() { *s = offset64 }
  61
  62 func (s *sum32) Sum32() uint32  { return uint32(*s) }
  63 func (s *sum32a) Sum32() uint32 { return uint32(*s) }
  64 func (s *sum64) Sum64() uint64  { return uint64(*s) }
  65 func (s *sum64a) Sum64() uint64 { return uint64(*s) }
  66
  67 func (s *sum32) Write(data []byte) (int, error) {
  68         hash := *s
  69         for _, c := range data {
  70                 hash *= prime32
  71                 hash ^= sum32(c)
  72         }
  73         *s = hash
  74         return len(data), nil
  75 }
  76
  77 func (s *sum32a) Write(data []byte) (int, error) {
  78         hash := *s
  79         for _, c := range data {
  80                 hash ^= sum32a(c)
  81                 hash *= prime32
  82         }
  83         *s = hash
  84         return len(data), nil
  85 }
  86
  87 func (s *sum64) Write(data []byte) (int, error) {
  88         hash := *s
  89         for _, c := range data {
  90                 hash *= prime64
  91                 hash ^= sum64(c)
  92         }
  93         *s = hash
  94         return len(data), nil
  95 }
  96
  97 func (s *sum64a) Write(data []byte) (int, error) {
  98         hash := *s
  99         for _, c := range data {
 100                 hash ^= sum64a(c)
 101                 hash *= prime64
 102         }
 103         *s = hash
 104         return len(data), nil
 105 }
 106
 107 func (s *sum32) Size() int  { return 4 }
 108 func (s *sum32a) Size() int { return 4 }
 109 func (s *sum64) Size() int  { return 8 }
 110 func (s *sum64a) Size() int { return 8 }
 111
 112 func (s *sum32) BlockSize() int  { return 1 }
 113 func (s *sum32a) BlockSize() int { return 1 }
 114 func (s *sum64) BlockSize() int  { return 1 }
 115 func (s *sum64a) BlockSize() int { return 1 }
 116
 117 func (s *sum32) Sum(in []byte) []byte {
 118         v := uint32(*s)
 119         return append(in, byte(v>>24), byte(v>>16), byte(v>>8), byte(v))
 120 }
 121
 122 func (s *sum32a) Sum(in []byte) []byte {
 123         v := uint32(*s)
 124         return append(in, byte(v>>24), byte(v>>16), byte(v>>8), byte(v))
 125 }
 126
 127 func (s *sum64) Sum(in []byte) []byte {
 128         v := uint64(*s)
 129         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))
 130 }
 131
 132 func (s *sum64a) Sum(in []byte) []byte {
 133         v := uint64(*s)
 134         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))
 135 }