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murmur32_gen.go
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murmur32_gen.go
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package murmur3
import "math/bits"
// Sum32 returns the murmur3 sum of data. It is equivalent to the following
// sequence (without the extra burden and the extra allocation):
//
// hasher := New32()
// hasher.Write(data)
// return hasher.Sum32()
func Sum32(data []byte) uint32 {
return SeedSum32(0, data)
}
// SeedSum32 returns the murmur3 sum of data with the digest initialized to
// seed.
//
// This reads and processes the data in chunks of little endian uint32s;
// thus, the returned hash is portable across architectures.
func SeedSum32(seed uint32, data []byte) (h1 uint32) {
h1 = seed
clen := uint32(len(data))
for len(data) >= 4 {
k1 := uint32(data[0]) | uint32(data[1])<<8 | uint32(data[2])<<16 | uint32(data[3])<<24
data = data[4:]
k1 *= c1_32
k1 = bits.RotateLeft32(k1, 15)
k1 *= c2_32
h1 ^= k1
h1 = bits.RotateLeft32(h1, 13)
h1 = h1*5 + 0xe6546b64
}
var k1 uint32
switch len(data) {
case 3:
k1 ^= uint32(data[2]) << 16
fallthrough
case 2:
k1 ^= uint32(data[1]) << 8
fallthrough
case 1:
k1 ^= uint32(data[0])
k1 *= c1_32
k1 = bits.RotateLeft32(k1, 15)
k1 *= c2_32
h1 ^= k1
}
h1 ^= uint32(clen)
h1 ^= h1 >> 16
h1 *= 0x85ebca6b
h1 ^= h1 >> 13
h1 *= 0xc2b2ae35
h1 ^= h1 >> 16
return h1
}
// StringSum32 is the string version of Sum32.
func StringSum32(data string) uint32 {
return SeedStringSum32(0, data)
}
// SeedStringSum32 is the string version of SeedSum32.
func SeedStringSum32(seed uint32, data string) (h1 uint32) {
h1 = seed
clen := uint32(len(data))
for len(data) >= 4 {
k1 := uint32(data[0]) | uint32(data[1])<<8 | uint32(data[2])<<16 | uint32(data[3])<<24
data = data[4:]
k1 *= c1_32
k1 = bits.RotateLeft32(k1, 15)
k1 *= c2_32
h1 ^= k1
h1 = bits.RotateLeft32(h1, 13)
h1 = h1*5 + 0xe6546b64
}
var k1 uint32
switch len(data) {
case 3:
k1 ^= uint32(data[2]) << 16
fallthrough
case 2:
k1 ^= uint32(data[1]) << 8
fallthrough
case 1:
k1 ^= uint32(data[0])
k1 *= c1_32
k1 = bits.RotateLeft32(k1, 15)
k1 *= c2_32
h1 ^= k1
}
h1 ^= uint32(clen)
h1 ^= h1 >> 16
h1 *= 0x85ebca6b
h1 ^= h1 >> 13
h1 *= 0xc2b2ae35
h1 ^= h1 >> 16
return h1
}