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murmur128_gen.go
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murmur128_gen.go
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// +build !go1.5 !amd64
package murmur3
import "math/bits"
// SeedSum128 returns the murmur3 sum of data with digests initialized to seed1
// and seed2.
//
// The canonical implementation allows only one uint32 seed; to imitate that
// behavior, use the same, uint32-max seed for seed1 and seed2.
//
// This reads and processes the data in chunks of little endian uint64s;
// thus, the returned hashes are portable across architectures.
func SeedSum128(seed1, seed2 uint64, data []byte) (h1 uint64, h2 uint64) {
return SeedStringSum128(seed1, seed2, strslice(data))
}
// Sum128 returns the murmur3 sum of data. It is equivalent to the following
// sequence (without the extra burden and the extra allocation):
// hasher := New128()
// hasher.Write(data)
// return hasher.Sum128()
func Sum128(data []byte) (h1 uint64, h2 uint64) {
return SeedStringSum128(0, 0, strslice(data))
}
// StringSum128 is the string version of Sum128.
func StringSum128(data string) (h1 uint64, h2 uint64) {
return SeedStringSum128(0, 0, data)
}
// SeedStringSum128 is the string version of SeedSum128.
func SeedStringSum128(seed1, seed2 uint64, data string) (h1 uint64, h2 uint64) {
h1, h2 = seed1, seed2
clen := len(data)
for len(data) >= 16 {
// yes, this is faster than using binary.LittleEndian.Uint64
k1 := uint64(data[0]) | uint64(data[1])<<8 | uint64(data[2])<<16 | uint64(data[3])<<24 | uint64(data[4])<<32 | uint64(data[5])<<40 | uint64(data[6])<<48 | uint64(data[7])<<56
k2 := uint64(data[8]) | uint64(data[9])<<8 | uint64(data[10])<<16 | uint64(data[11])<<24 | uint64(data[12])<<32 | uint64(data[13])<<40 | uint64(data[14])<<48 | uint64(data[15])<<56
data = data[16:]
k1 *= c1_128
k1 = bits.RotateLeft64(k1, 31)
k1 *= c2_128
h1 ^= k1
h1 = bits.RotateLeft64(h1, 27)
h1 += h2
h1 = h1*5 + 0x52dce729
k2 *= c2_128
k2 = bits.RotateLeft64(k2, 33)
k2 *= c1_128
h2 ^= k2
h2 = bits.RotateLeft64(h2, 31)
h2 += h1
h2 = h2*5 + 0x38495ab5
}
var k1, k2 uint64
switch len(data) {
case 15:
k2 ^= uint64(data[14]) << 48
fallthrough
case 14:
k2 ^= uint64(data[13]) << 40
fallthrough
case 13:
k2 ^= uint64(data[12]) << 32
fallthrough
case 12:
k2 ^= uint64(data[11]) << 24
fallthrough
case 11:
k2 ^= uint64(data[10]) << 16
fallthrough
case 10:
k2 ^= uint64(data[9]) << 8
fallthrough
case 9:
k2 ^= uint64(data[8]) << 0
k2 *= c2_128
k2 = bits.RotateLeft64(k2, 33)
k2 *= c1_128
h2 ^= k2
fallthrough
case 8:
k1 ^= uint64(data[7]) << 56
fallthrough
case 7:
k1 ^= uint64(data[6]) << 48
fallthrough
case 6:
k1 ^= uint64(data[5]) << 40
fallthrough
case 5:
k1 ^= uint64(data[4]) << 32
fallthrough
case 4:
k1 ^= uint64(data[3]) << 24
fallthrough
case 3:
k1 ^= uint64(data[2]) << 16
fallthrough
case 2:
k1 ^= uint64(data[1]) << 8
fallthrough
case 1:
k1 ^= uint64(data[0]) << 0
k1 *= c1_128
k1 = bits.RotateLeft64(k1, 31)
k1 *= c2_128
h1 ^= k1
}
h1 ^= uint64(clen)
h2 ^= uint64(clen)
h1 += h2
h2 += h1
h1 = fmix64(h1)
h2 = fmix64(h2)
h1 += h2
h2 += h1
return h1, h2
}