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//go:build (!amd64 && !arm64) || appengine || !gc || purego || noasm
// +build !amd64,!arm64 appengine !gc purego noasm
package xxhash
// Sum64 computes the 64-bit xxHash digest of b.
func Sum64(b []byte) uint64 {
// A simpler version would be
// d := New()
// d.Write(b)
// return d.Sum64()
// but this is faster, particularly for small inputs.
n := len(b)
var h uint64
if n >= 32 {
v1 := primes[0] + prime2
v2 := prime2
v3 := uint64(0)
v4 := -primes[0]
for len(b) >= 32 {
v1 = round(v1, u64(b[0:8:len(b)]))
v2 = round(v2, u64(b[8:16:len(b)]))
v3 = round(v3, u64(b[16:24:len(b)]))
v4 = round(v4, u64(b[24:32:len(b)]))
b = b[32:len(b):len(b)]
}
h = rol1(v1) + rol7(v2) + rol12(v3) + rol18(v4)
h = mergeRound(h, v1)
h = mergeRound(h, v2)
h = mergeRound(h, v3)
h = mergeRound(h, v4)
} else {
h = prime5
}
h += uint64(n)
for ; len(b) >= 8; b = b[8:] {
k1 := round(0, u64(b[:8]))
h ^= k1
h = rol27(h)*prime1 + prime4
}
if len(b) >= 4 {
h ^= uint64(u32(b[:4])) * prime1
h = rol23(h)*prime2 + prime3
b = b[4:]
}
for ; len(b) > 0; b = b[1:] {
h ^= uint64(b[0]) * prime5
h = rol11(h) * prime1
}
h ^= h >> 33
h *= prime2
h ^= h >> 29
h *= prime3
h ^= h >> 32
return h
}
func writeBlocks(d *Digest, b []byte) int {
v1, v2, v3, v4 := d.v1, d.v2, d.v3, d.v4
n := len(b)
for len(b) >= 32 {
v1 = round(v1, u64(b[0:8:len(b)]))
v2 = round(v2, u64(b[8:16:len(b)]))
v3 = round(v3, u64(b[16:24:len(b)]))
v4 = round(v4, u64(b[24:32:len(b)]))
b = b[32:len(b):len(b)]
}
d.v1, d.v2, d.v3, d.v4 = v1, v2, v3, v4
return n - len(b)
}
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