1// +build !amd64 appengine !gc purego 2 3package xxhash 4 5// Sum64 computes the 64-bit xxHash digest of b. 6func 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 64func 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} 77