88 lines
2.2 KiB
Go
88 lines
2.2 KiB
Go
// Package fnv128a implements FNV-1 and FNV-1a, non-cryptographic hash functions
|
|
// created by Glenn Fowler, Landon Curt Noll, and Phong Vo.
|
|
// See https://en.wikipedia.org/wiki/Fowler-Noll-Vo_hash_function.
|
|
//
|
|
// Write() algorithm taken and modified from github.com/romain-jacotin/quic
|
|
package fnv128a
|
|
|
|
import "hash"
|
|
|
|
// Hash128 is the common interface implemented by all 128-bit hash functions.
|
|
type Hash128 interface {
|
|
hash.Hash
|
|
Sum128() (uint64, uint64)
|
|
}
|
|
|
|
type sum128a struct {
|
|
v0, v1, v2, v3 uint64
|
|
}
|
|
|
|
var _ Hash128 = &sum128a{}
|
|
|
|
// New1 returns a new 128-bit FNV-1a hash.Hash.
|
|
func New() Hash128 {
|
|
s := &sum128a{}
|
|
s.Reset()
|
|
return s
|
|
}
|
|
|
|
func (s *sum128a) Reset() {
|
|
s.v0 = 0x6295C58D
|
|
s.v1 = 0x62B82175
|
|
s.v2 = 0x07BB0142
|
|
s.v3 = 0x6C62272E
|
|
}
|
|
|
|
func (s *sum128a) Sum128() (uint64, uint64) {
|
|
return s.v3<<32 | s.v2, s.v1<<32 | s.v0
|
|
}
|
|
|
|
func (s *sum128a) Write(data []byte) (int, error) {
|
|
var t0, t1, t2, t3 uint64
|
|
const fnv128PrimeLow = 0x0000013B
|
|
const fnv128PrimeShift = 24
|
|
|
|
for _, v := range data {
|
|
// xor the bottom with the current octet
|
|
s.v0 ^= uint64(v)
|
|
|
|
// multiply by the 128 bit FNV magic prime mod 2^128
|
|
// fnv_prime = 309485009821345068724781371 (decimal)
|
|
// = 0x0000000001000000000000000000013B (hexadecimal)
|
|
// = 0x00000000 0x01000000 0x00000000 0x0000013B (in 4*32 words)
|
|
// = 0x0 1<<fnv128PrimeShift 0x0 fnv128PrimeLow
|
|
//
|
|
// fnv128PrimeLow = 0x0000013B
|
|
// fnv128PrimeShift = 24
|
|
|
|
// multiply by the lowest order digit base 2^32 and by the other non-zero digit
|
|
t0 = s.v0 * fnv128PrimeLow
|
|
t1 = s.v1 * fnv128PrimeLow
|
|
t2 = s.v2*fnv128PrimeLow + s.v0<<fnv128PrimeShift
|
|
t3 = s.v3*fnv128PrimeLow + s.v1<<fnv128PrimeShift
|
|
|
|
// propagate carries
|
|
t1 += (t0 >> 32)
|
|
t2 += (t1 >> 32)
|
|
t3 += (t2 >> 32)
|
|
|
|
s.v0 = t0 & 0xffffffff
|
|
s.v1 = t1 & 0xffffffff
|
|
s.v2 = t2 & 0xffffffff
|
|
s.v3 = t3 // & 0xffffffff
|
|
// Doing a s.v3 &= 0xffffffff is not really needed since it simply
|
|
// removes multiples of 2^128. We can discard these excess bits
|
|
// outside of the loop when writing the hash in Little Endian.
|
|
}
|
|
|
|
return len(data), nil
|
|
}
|
|
|
|
func (s *sum128a) Size() int { return 16 }
|
|
|
|
func (s *sum128a) BlockSize() int { return 1 }
|
|
|
|
func (s *sum128a) Sum(in []byte) []byte {
|
|
panic("FNV: not supported")
|
|
}
|