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	}