1package murmur3
2
3import (
4	"hash"
5)
6
7// Make sure interfaces are correctly implemented.
8var (
9	_ hash.Hash   = new(digest64)
10	_ hash.Hash64 = new(digest64)
11	_ bmixer      = new(digest64)
12)
13
14// digest64 is half a digest128.
15type digest64 digest128
16
17// New64 returns a 64-bit hasher
18func New64() hash.Hash64 { return New64WithSeed(0) }
19
20// New64WithSeed returns a 64-bit hasher set with explicit seed value
21func New64WithSeed(seed uint32) hash.Hash64 {
22	d := (*digest64)(New128WithSeed(seed).(*digest128))
23	return d
24}
25
26func (d *digest64) Sum(b []byte) []byte {
27	h1 := d.Sum64()
28	return append(b,
29		byte(h1>>56), byte(h1>>48), byte(h1>>40), byte(h1>>32),
30		byte(h1>>24), byte(h1>>16), byte(h1>>8), byte(h1))
31}
32
33func (d *digest64) Sum64() uint64 {
34	h1, _ := (*digest128)(d).Sum128()
35	return h1
36}
37
38// Sum64 returns the MurmurHash3 sum of data. It is equivalent to the
39// following sequence (without the extra burden and the extra allocation):
40//     hasher := New64()
41//     hasher.Write(data)
42//     return hasher.Sum64()
43func Sum64(data []byte) uint64 { return Sum64WithSeed(data, 0) }
44
45// Sum64WithSeed returns the MurmurHash3 sum of data. It is equivalent to the
46// following sequence (without the extra burden and the extra allocation):
47//     hasher := New64WithSeed(seed)
48//     hasher.Write(data)
49//     return hasher.Sum64()
50func Sum64WithSeed(data []byte, seed uint32) uint64 {
51	d := &digest128{h1: uint64(seed), h2: uint64(seed)}
52	d.seed = seed
53	d.tail = d.bmix(data)
54	d.clen = len(data)
55	h1, _ := d.Sum128()
56	return h1
57}
58