Elia Battiston | 4750d3c | 2022-07-14 13:24:56 +0000 | [diff] [blame] | 1 | // +build !amd64 appengine !gc purego |
| 2 | |
| 3 | package xxhash |
| 4 | |
| 5 | // Sum64 computes the 64-bit xxHash digest of b. |
| 6 | func Sum64(b []byte) uint64 { |
| 7 | // A simpler version would be |
| 8 | // d := New() |
| 9 | // d.Write(b) |
| 10 | // return d.Sum64() |
| 11 | // but this is faster, particularly for small inputs. |
| 12 | |
| 13 | n := len(b) |
| 14 | var h uint64 |
| 15 | |
| 16 | if n >= 32 { |
| 17 | v1 := prime1v + prime2 |
| 18 | v2 := prime2 |
| 19 | v3 := uint64(0) |
| 20 | v4 := -prime1v |
| 21 | for len(b) >= 32 { |
| 22 | v1 = round(v1, u64(b[0:8:len(b)])) |
| 23 | v2 = round(v2, u64(b[8:16:len(b)])) |
| 24 | v3 = round(v3, u64(b[16:24:len(b)])) |
| 25 | v4 = round(v4, u64(b[24:32:len(b)])) |
| 26 | b = b[32:len(b):len(b)] |
| 27 | } |
| 28 | h = rol1(v1) + rol7(v2) + rol12(v3) + rol18(v4) |
| 29 | h = mergeRound(h, v1) |
| 30 | h = mergeRound(h, v2) |
| 31 | h = mergeRound(h, v3) |
| 32 | h = mergeRound(h, v4) |
| 33 | } else { |
| 34 | h = prime5 |
| 35 | } |
| 36 | |
| 37 | h += uint64(n) |
| 38 | |
| 39 | i, end := 0, len(b) |
| 40 | for ; i+8 <= end; i += 8 { |
| 41 | k1 := round(0, u64(b[i:i+8:len(b)])) |
| 42 | h ^= k1 |
| 43 | h = rol27(h)*prime1 + prime4 |
| 44 | } |
| 45 | if i+4 <= end { |
| 46 | h ^= uint64(u32(b[i:i+4:len(b)])) * prime1 |
| 47 | h = rol23(h)*prime2 + prime3 |
| 48 | i += 4 |
| 49 | } |
| 50 | for ; i < end; i++ { |
| 51 | h ^= uint64(b[i]) * prime5 |
| 52 | h = rol11(h) * prime1 |
| 53 | } |
| 54 | |
| 55 | h ^= h >> 33 |
| 56 | h *= prime2 |
| 57 | h ^= h >> 29 |
| 58 | h *= prime3 |
| 59 | h ^= h >> 32 |
| 60 | |
| 61 | return h |
| 62 | } |
| 63 | |
| 64 | func writeBlocks(d *Digest, b []byte) int { |
| 65 | v1, v2, v3, v4 := d.v1, d.v2, d.v3, d.v4 |
| 66 | n := len(b) |
| 67 | for len(b) >= 32 { |
| 68 | v1 = round(v1, u64(b[0:8:len(b)])) |
| 69 | v2 = round(v2, u64(b[8:16:len(b)])) |
| 70 | v3 = round(v3, u64(b[16:24:len(b)])) |
| 71 | v4 = round(v4, u64(b[24:32:len(b)])) |
| 72 | b = b[32:len(b):len(b)] |
| 73 | } |
| 74 | d.v1, d.v2, d.v3, d.v4 = v1, v2, v3, v4 |
| 75 | return n - len(b) |
| 76 | } |