fnv.go

Documentation: hash/fnv

		 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  //
		10  // All the hash.Hash implementations returned by this package also
		11  // implement encoding.BinaryMarshaler and encoding.BinaryUnmarshaler to
		12  // marshal and unmarshal the internal state of the hash.
		13  package fnv
		14  
		15  import (
		16  	"errors"
		17  	"hash"
		18  	"math/bits"
		19  )
		20  
		21  type (
		22  	sum32	 uint32
		23  	sum32a	uint32
		24  	sum64	 uint64
		25  	sum64a	uint64
		26  	sum128	[2]uint64
		27  	sum128a [2]uint64
		28  )
		29  
		30  const (
		31  	offset32				= 2166136261
		32  	offset64				= 14695981039346656037
		33  	offset128Lower	= 0x62b821756295c58d
		34  	offset128Higher = 0x6c62272e07bb0142
		35  	prime32				 = 16777619
		36  	prime64				 = 1099511628211
		37  	prime128Lower	 = 0x13b
		38  	prime128Shift	 = 24
		39  )
		40  
		41  // New32 returns a new 32-bit FNV-1 hash.Hash.
		42  // Its Sum method will lay the value out in big-endian byte order.
		43  func New32() hash.Hash32 {
		44  	var s sum32 = offset32
		45  	return &s
		46  }
		47  
		48  // New32a returns a new 32-bit FNV-1a hash.Hash.
		49  // Its Sum method will lay the value out in big-endian byte order.
		50  func New32a() hash.Hash32 {
		51  	var s sum32a = offset32
		52  	return &s
		53  }
		54  
		55  // New64 returns a new 64-bit FNV-1 hash.Hash.
		56  // Its Sum method will lay the value out in big-endian byte order.
		57  func New64() hash.Hash64 {
		58  	var s sum64 = offset64
		59  	return &s
		60  }
		61  
		62  // New64a returns a new 64-bit FNV-1a hash.Hash.
		63  // Its Sum method will lay the value out in big-endian byte order.
		64  func New64a() hash.Hash64 {
		65  	var s sum64a = offset64
		66  	return &s
		67  }
		68  
		69  // New128 returns a new 128-bit FNV-1 hash.Hash.
		70  // Its Sum method will lay the value out in big-endian byte order.
		71  func New128() hash.Hash {
		72  	var s sum128
		73  	s[0] = offset128Higher
		74  	s[1] = offset128Lower
		75  	return &s
		76  }
		77  
		78  // New128a returns a new 128-bit FNV-1a hash.Hash.
		79  // Its Sum method will lay the value out in big-endian byte order.
		80  func New128a() hash.Hash {
		81  	var s sum128a
		82  	s[0] = offset128Higher
		83  	s[1] = offset128Lower
		84  	return &s
		85  }
		86  
		87  func (s *sum32) Reset()	 { *s = offset32 }
		88  func (s *sum32a) Reset()	{ *s = offset32 }
		89  func (s *sum64) Reset()	 { *s = offset64 }
		90  func (s *sum64a) Reset()	{ *s = offset64 }
		91  func (s *sum128) Reset()	{ s[0] = offset128Higher; s[1] = offset128Lower }
		92  func (s *sum128a) Reset() { s[0] = offset128Higher; s[1] = offset128Lower }
		93  
		94  func (s *sum32) Sum32() uint32	{ return uint32(*s) }
		95  func (s *sum32a) Sum32() uint32 { return uint32(*s) }
		96  func (s *sum64) Sum64() uint64	{ return uint64(*s) }
		97  func (s *sum64a) Sum64() uint64 { return uint64(*s) }
		98  
		99  func (s *sum32) Write(data []byte) (int, error) {
	 100  	hash := *s
	 101  	for _, c := range data {
	 102  		hash *= prime32
	 103  		hash ^= sum32(c)
	 104  	}
	 105  	*s = hash
	 106  	return len(data), nil
	 107  }
	 108  
	 109  func (s *sum32a) Write(data []byte) (int, error) {
	 110  	hash := *s
	 111  	for _, c := range data {
	 112  		hash ^= sum32a(c)
	 113  		hash *= prime32
	 114  	}
	 115  	*s = hash
	 116  	return len(data), nil
	 117  }
	 118  
	 119  func (s *sum64) Write(data []byte) (int, error) {
	 120  	hash := *s
	 121  	for _, c := range data {
	 122  		hash *= prime64
	 123  		hash ^= sum64(c)
	 124  	}
	 125  	*s = hash
	 126  	return len(data), nil
	 127  }
	 128  
	 129  func (s *sum64a) Write(data []byte) (int, error) {
	 130  	hash := *s
	 131  	for _, c := range data {
	 132  		hash ^= sum64a(c)
	 133  		hash *= prime64
	 134  	}
	 135  	*s = hash
	 136  	return len(data), nil
	 137  }
	 138  
	 139  func (s *sum128) Write(data []byte) (int, error) {
	 140  	for _, c := range data {
	 141  		// Compute the multiplication
	 142  		s0, s1 := bits.Mul64(prime128Lower, s[1])
	 143  		s0 += s[1]<<prime128Shift + prime128Lower*s[0]
	 144  		// Update the values
	 145  		s[1] = s1
	 146  		s[0] = s0
	 147  		s[1] ^= uint64(c)
	 148  	}
	 149  	return len(data), nil
	 150  }
	 151  
	 152  func (s *sum128a) Write(data []byte) (int, error) {
	 153  	for _, c := range data {
	 154  		s[1] ^= uint64(c)
	 155  		// Compute the multiplication
	 156  		s0, s1 := bits.Mul64(prime128Lower, s[1])
	 157  		s0 += s[1]<<prime128Shift + prime128Lower*s[0]
	 158  		// Update the values
	 159  		s[1] = s1
	 160  		s[0] = s0
	 161  	}
	 162  	return len(data), nil
	 163  }
	 164  
	 165  func (s *sum32) Size() int	 { return 4 }
	 166  func (s *sum32a) Size() int	{ return 4 }
	 167  func (s *sum64) Size() int	 { return 8 }
	 168  func (s *sum64a) Size() int	{ return 8 }
	 169  func (s *sum128) Size() int	{ return 16 }
	 170  func (s *sum128a) Size() int { return 16 }
	 171  
	 172  func (s *sum32) BlockSize() int	 { return 1 }
	 173  func (s *sum32a) BlockSize() int	{ return 1 }
	 174  func (s *sum64) BlockSize() int	 { return 1 }
	 175  func (s *sum64a) BlockSize() int	{ return 1 }
	 176  func (s *sum128) BlockSize() int	{ return 1 }
	 177  func (s *sum128a) BlockSize() int { return 1 }
	 178  
	 179  func (s *sum32) Sum(in []byte) []byte {
	 180  	v := uint32(*s)
	 181  	return append(in, byte(v>>24), byte(v>>16), byte(v>>8), byte(v))
	 182  }
	 183  
	 184  func (s *sum32a) Sum(in []byte) []byte {
	 185  	v := uint32(*s)
	 186  	return append(in, byte(v>>24), byte(v>>16), byte(v>>8), byte(v))
	 187  }
	 188  
	 189  func (s *sum64) Sum(in []byte) []byte {
	 190  	v := uint64(*s)
	 191  	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))
	 192  }
	 193  
	 194  func (s *sum64a) Sum(in []byte) []byte {
	 195  	v := uint64(*s)
	 196  	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))
	 197  }
	 198  
	 199  func (s *sum128) Sum(in []byte) []byte {
	 200  	return append(in,
	 201  		byte(s[0]>>56), byte(s[0]>>48), byte(s[0]>>40), byte(s[0]>>32), byte(s[0]>>24), byte(s[0]>>16), byte(s[0]>>8), byte(s[0]),
	 202  		byte(s[1]>>56), byte(s[1]>>48), byte(s[1]>>40), byte(s[1]>>32), byte(s[1]>>24), byte(s[1]>>16), byte(s[1]>>8), byte(s[1]),
	 203  	)
	 204  }
	 205  
	 206  func (s *sum128a) Sum(in []byte) []byte {
	 207  	return append(in,
	 208  		byte(s[0]>>56), byte(s[0]>>48), byte(s[0]>>40), byte(s[0]>>32), byte(s[0]>>24), byte(s[0]>>16), byte(s[0]>>8), byte(s[0]),
	 209  		byte(s[1]>>56), byte(s[1]>>48), byte(s[1]>>40), byte(s[1]>>32), byte(s[1]>>24), byte(s[1]>>16), byte(s[1]>>8), byte(s[1]),
	 210  	)
	 211  }
	 212  
	 213  const (
	 214  	magic32					= "fnv\x01"
	 215  	magic32a				 = "fnv\x02"
	 216  	magic64					= "fnv\x03"
	 217  	magic64a				 = "fnv\x04"
	 218  	magic128				 = "fnv\x05"
	 219  	magic128a				= "fnv\x06"
	 220  	marshaledSize32	= len(magic32) + 4
	 221  	marshaledSize64	= len(magic64) + 8
	 222  	marshaledSize128 = len(magic128) + 8*2
	 223  )
	 224  
	 225  func (s *sum32) MarshalBinary() ([]byte, error) {
	 226  	b := make([]byte, 0, marshaledSize32)
	 227  	b = append(b, magic32...)
	 228  	b = appendUint32(b, uint32(*s))
	 229  	return b, nil
	 230  }
	 231  
	 232  func (s *sum32a) MarshalBinary() ([]byte, error) {
	 233  	b := make([]byte, 0, marshaledSize32)
	 234  	b = append(b, magic32a...)
	 235  	b = appendUint32(b, uint32(*s))
	 236  	return b, nil
	 237  }
	 238  
	 239  func (s *sum64) MarshalBinary() ([]byte, error) {
	 240  	b := make([]byte, 0, marshaledSize64)
	 241  	b = append(b, magic64...)
	 242  	b = appendUint64(b, uint64(*s))
	 243  	return b, nil
	 244  
	 245  }
	 246  
	 247  func (s *sum64a) MarshalBinary() ([]byte, error) {
	 248  	b := make([]byte, 0, marshaledSize64)
	 249  	b = append(b, magic64a...)
	 250  	b = appendUint64(b, uint64(*s))
	 251  	return b, nil
	 252  }
	 253  
	 254  func (s *sum128) MarshalBinary() ([]byte, error) {
	 255  	b := make([]byte, 0, marshaledSize128)
	 256  	b = append(b, magic128...)
	 257  	b = appendUint64(b, s[0])
	 258  	b = appendUint64(b, s[1])
	 259  	return b, nil
	 260  }
	 261  
	 262  func (s *sum128a) MarshalBinary() ([]byte, error) {
	 263  	b := make([]byte, 0, marshaledSize128)
	 264  	b = append(b, magic128a...)
	 265  	b = appendUint64(b, s[0])
	 266  	b = appendUint64(b, s[1])
	 267  	return b, nil
	 268  }
	 269  
	 270  func (s *sum32) UnmarshalBinary(b []byte) error {
	 271  	if len(b) < len(magic32) || string(b[:len(magic32)]) != magic32 {
	 272  		return errors.New("hash/fnv: invalid hash state identifier")
	 273  	}
	 274  	if len(b) != marshaledSize32 {
	 275  		return errors.New("hash/fnv: invalid hash state size")
	 276  	}
	 277  	*s = sum32(readUint32(b[4:]))
	 278  	return nil
	 279  }
	 280  
	 281  func (s *sum32a) UnmarshalBinary(b []byte) error {
	 282  	if len(b) < len(magic32a) || string(b[:len(magic32a)]) != magic32a {
	 283  		return errors.New("hash/fnv: invalid hash state identifier")
	 284  	}
	 285  	if len(b) != marshaledSize32 {
	 286  		return errors.New("hash/fnv: invalid hash state size")
	 287  	}
	 288  	*s = sum32a(readUint32(b[4:]))
	 289  	return nil
	 290  }
	 291  
	 292  func (s *sum64) UnmarshalBinary(b []byte) error {
	 293  	if len(b) < len(magic64) || string(b[:len(magic64)]) != magic64 {
	 294  		return errors.New("hash/fnv: invalid hash state identifier")
	 295  	}
	 296  	if len(b) != marshaledSize64 {
	 297  		return errors.New("hash/fnv: invalid hash state size")
	 298  	}
	 299  	*s = sum64(readUint64(b[4:]))
	 300  	return nil
	 301  }
	 302  
	 303  func (s *sum64a) UnmarshalBinary(b []byte) error {
	 304  	if len(b) < len(magic64a) || string(b[:len(magic64a)]) != magic64a {
	 305  		return errors.New("hash/fnv: invalid hash state identifier")
	 306  	}
	 307  	if len(b) != marshaledSize64 {
	 308  		return errors.New("hash/fnv: invalid hash state size")
	 309  	}
	 310  	*s = sum64a(readUint64(b[4:]))
	 311  	return nil
	 312  }
	 313  
	 314  func (s *sum128) UnmarshalBinary(b []byte) error {
	 315  	if len(b) < len(magic128) || string(b[:len(magic128)]) != magic128 {
	 316  		return errors.New("hash/fnv: invalid hash state identifier")
	 317  	}
	 318  	if len(b) != marshaledSize128 {
	 319  		return errors.New("hash/fnv: invalid hash state size")
	 320  	}
	 321  	s[0] = readUint64(b[4:])
	 322  	s[1] = readUint64(b[12:])
	 323  	return nil
	 324  }
	 325  
	 326  func (s *sum128a) UnmarshalBinary(b []byte) error {
	 327  	if len(b) < len(magic128a) || string(b[:len(magic128a)]) != magic128a {
	 328  		return errors.New("hash/fnv: invalid hash state identifier")
	 329  	}
	 330  	if len(b) != marshaledSize128 {
	 331  		return errors.New("hash/fnv: invalid hash state size")
	 332  	}
	 333  	s[0] = readUint64(b[4:])
	 334  	s[1] = readUint64(b[12:])
	 335  	return nil
	 336  }
	 337  
	 338  func readUint32(b []byte) uint32 {
	 339  	_ = b[3]
	 340  	return uint32(b[3]) | uint32(b[2])<<8 | uint32(b[1])<<16 | uint32(b[0])<<24
	 341  }
	 342  
	 343  func appendUint32(b []byte, x uint32) []byte {
	 344  	a := [4]byte{
	 345  		byte(x >> 24),
	 346  		byte(x >> 16),
	 347  		byte(x >> 8),
	 348  		byte(x),
	 349  	}
	 350  	return append(b, a[:]...)
	 351  }
	 352  
	 353  func appendUint64(b []byte, x uint64) []byte {
	 354  	a := [8]byte{
	 355  		byte(x >> 56),
	 356  		byte(x >> 48),
	 357  		byte(x >> 40),
	 358  		byte(x >> 32),
	 359  		byte(x >> 24),
	 360  		byte(x >> 16),
	 361  		byte(x >> 8),
	 362  		byte(x),
	 363  	}
	 364  	return append(b, a[:]...)
	 365  }
	 366  
	 367  func readUint64(b []byte) uint64 {
	 368  	_ = b[7]
	 369  	return uint64(b[7]) | uint64(b[6])<<8 | uint64(b[5])<<16 | uint64(b[4])<<24 |
	 370  		uint64(b[3])<<32 | uint64(b[2])<<40 | uint64(b[1])<<48 | uint64(b[0])<<56
	 371  }
	 372
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