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hash.go
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hash.go
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package bloom
// MurmurHash3 implementation adapted from Sébastien Paolacci
// github.com/spaolacci/murmur3, released under BSD-3-Clause.
const (
c1 = 0x87c37b91114253d5
c2 = 0x4cf5ad432745937f
)
func fmix(k uint64) uint64 {
k ^= k >> 33
k *= 0xff51afd7ed558ccd
k ^= k >> 33
k *= 0xc4ceb9fe1a85ec53
k ^= k >> 33
return k
}
func uint64byte(b []byte) uint64 {
return uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24 |
uint64(b[4])<<32 | uint64(b[5])<<40 | uint64(b[6])<<48 | uint64(b[7])<<56
}
func uint64string(s string) uint64 {
return uint64(s[0]) | uint64(s[1])<<8 | uint64(s[2])<<16 | uint64(s[3])<<24 |
uint64(s[4])<<32 | uint64(s[5])<<40 | uint64(s[6])<<48 | uint64(s[7])<<56
}
func hash(b []byte) (h1, h2 uint64) {
nblocks := len(b) / 16
for i := 0; i < nblocks; i++ {
j := 16 * i
k1, k2 := uint64byte(b[j:j+8]), uint64byte(b[j+8:j+16])
k1 *= c1
k1 = (k1 << 31) | (k1 >> 33) // rotl64(k1, 31)
k1 *= c2
h1 ^= k1
h1 = (h1 << 27) | (h1 >> 37) // rotl64(h1, 27)
h1 += h2
h1 = h1*5 + 0x52dce729
k2 *= c2
k2 = (k2 << 33) | (k2 >> 31) // rotl64(k2, 33)
k2 *= c1
h2 ^= k2
h2 = (h2 << 31) | (h2 >> 33) // rotl64(h2, 31)
h2 += h1
h2 = h2*5 + 0x38495ab5
}
tail := b[nblocks*16:]
var k1, k2 uint64
switch len(tail) {
case 15:
k2 ^= uint64(tail[14]) << 48
fallthrough
case 14:
k2 ^= uint64(tail[13]) << 40
fallthrough
case 13:
k2 ^= uint64(tail[12]) << 32
fallthrough
case 12:
k2 ^= uint64(tail[11]) << 24
fallthrough
case 11:
k2 ^= uint64(tail[10]) << 16
fallthrough
case 10:
k2 ^= uint64(tail[9]) << 8
fallthrough
case 9:
k2 ^= uint64(tail[8]) << 0
k2 *= c2
k2 = (k2 << 33) | (k2 >> 31) // rotl64(k2, 33)
k2 *= c1
h2 ^= k2
fallthrough
case 8:
k1 ^= uint64(tail[7]) << 56
fallthrough
case 7:
k1 ^= uint64(tail[6]) << 48
fallthrough
case 6:
k1 ^= uint64(tail[5]) << 40
fallthrough
case 5:
k1 ^= uint64(tail[4]) << 32
fallthrough
case 4:
k1 ^= uint64(tail[3]) << 24
fallthrough
case 3:
k1 ^= uint64(tail[2]) << 16
fallthrough
case 2:
k1 ^= uint64(tail[1]) << 8
fallthrough
case 1:
k1 ^= uint64(tail[0]) << 0
k1 *= c1
k1 = (k1 << 31) | (k1 >> 33) // rotl64(k1, 31)
k1 *= c2
h1 ^= k1
}
h1 ^= uint64(len(b))
h2 ^= uint64(len(b))
h1 += h2
h2 += h1
h1, h2 = fmix(h1), fmix(h2)
h1 += h2
h2 += h1
return
}
func hashString(s string) (h1, h2 uint64) {
nblocks := len(s) / 16
for i := 0; i < nblocks; i++ {
j := 16 * i
k1, k2 := uint64string(s[j:j+8]), uint64string(s[j+8:j+16])
k1 *= c1
k1 = (k1 << 31) | (k1 >> 33) // rotl64(k1, 31)
k1 *= c2
h1 ^= k1
h1 = (h1 << 27) | (h1 >> 37) // rotl64(h1, 27)
h1 += h2
h1 = h1*5 + 0x52dce729
k2 *= c2
k2 = (k2 << 33) | (k2 >> 31) // rotl64(k2, 33)
k2 *= c1
h2 ^= k2
h2 = (h2 << 31) | (h2 >> 33) // rotl64(h2, 31)
h2 += h1
h2 = h2*5 + 0x38495ab5
}
tail := s[nblocks*16:]
var k1, k2 uint64
switch len(tail) {
case 15:
k2 ^= uint64(tail[14]) << 48
fallthrough
case 14:
k2 ^= uint64(tail[13]) << 40
fallthrough
case 13:
k2 ^= uint64(tail[12]) << 32
fallthrough
case 12:
k2 ^= uint64(tail[11]) << 24
fallthrough
case 11:
k2 ^= uint64(tail[10]) << 16
fallthrough
case 10:
k2 ^= uint64(tail[9]) << 8
fallthrough
case 9:
k2 ^= uint64(tail[8]) << 0
k2 *= c2
k2 = (k2 << 33) | (k2 >> 31) // rotl64(k2, 33)
k2 *= c1
h2 ^= k2
fallthrough
case 8:
k1 ^= uint64(tail[7]) << 56
fallthrough
case 7:
k1 ^= uint64(tail[6]) << 48
fallthrough
case 6:
k1 ^= uint64(tail[5]) << 40
fallthrough
case 5:
k1 ^= uint64(tail[4]) << 32
fallthrough
case 4:
k1 ^= uint64(tail[3]) << 24
fallthrough
case 3:
k1 ^= uint64(tail[2]) << 16
fallthrough
case 2:
k1 ^= uint64(tail[1]) << 8
fallthrough
case 1:
k1 ^= uint64(tail[0]) << 0
k1 *= c1
k1 = (k1 << 31) | (k1 >> 33) // rotl64(k1, 31)
k1 *= c2
h1 ^= k1
}
h1 ^= uint64(len(s))
h2 ^= uint64(len(s))
h1 += h2
h2 += h1
h1, h2 = fmix(h1), fmix(h2)
h1 += h2
h2 += h1
return
}