GoToSocial/vendor/github.com/zeebo/xxh3/hash64_seed.go

package xxh3

import "math/bits"

// HashSeed returns the hash of the byte slice with given seed.
func HashSeed(b []byte, seed uint64) uint64 {
	return hashAnySeed(*(*str)(ptr(&b)), seed)

}

// HashStringSeed returns the hash of the string slice with given seed.
func HashStringSeed(s string, seed uint64) uint64 {
	return hashAnySeed(*(*str)(ptr(&s)), seed)
}

func hashAnySeed(s str, seed uint64) (acc u64) {
	p, l := s.p, s.l

	switch {
	case l <= 16:
		switch {
		case l > 8:
			inputlo := readU64(p, 0) ^ (key64_024 ^ key64_032 + seed)
			inputhi := readU64(p, ui(l)-8) ^ (key64_040 ^ key64_048 - seed)
			folded := mulFold64(inputlo, inputhi)
			return xxh3Avalanche(u64(l) + bits.ReverseBytes64(inputlo) + inputhi + folded)

		case l > 3:
			seed ^= u64(bits.ReverseBytes32(u32(seed))) << 32
			input1 := readU32(p, 0)
			input2 := readU32(p, ui(l)-4)
			input64 := u64(input2) + u64(input1)<<32
			keyed := input64 ^ (key64_008 ^ key64_016 - seed)
			return rrmxmx(keyed, u64(l))

		case l == 3: // 3
			c12 := u64(readU16(p, 0))
			c3 := u64(readU8(p, 2))
			acc = c12<<16 + c3 + 3<<8

		case l > 1: // 2
			c12 := u64(readU16(p, 0))
			acc = c12*(1<<24+1)>>8 + 2<<8

		case l == 1: // 1
			c1 := u64(readU8(p, 0))
			acc = c1*(1<<24+1<<16+1) + 1<<8

		default:
			return xxhAvalancheSmall(seed ^ key64_056 ^ key64_064)
		}

		acc ^= u64(key32_000^key32_004) + seed
		return xxhAvalancheSmall(acc)

	case l <= 128:
		acc = u64(l) * prime64_1

		if l > 32 {
			if l > 64 {
				if l > 96 {
					acc += mulFold64(readU64(p, 6*8)^(key64_096+seed), readU64(p, 7*8)^(key64_104-seed))
					acc += mulFold64(readU64(p, ui(l)-8*8)^(key64_112+seed), readU64(p, ui(l)-7*8)^(key64_120-seed))
				} // 96
				acc += mulFold64(readU64(p, 4*8)^(key64_064+seed), readU64(p, 5*8)^(key64_072-seed))
				acc += mulFold64(readU64(p, ui(l)-6*8)^(key64_080+seed), readU64(p, ui(l)-5*8)^(key64_088-seed))
			} // 64
			acc += mulFold64(readU64(p, 2*8)^(key64_032+seed), readU64(p, 3*8)^(key64_040-seed))
			acc += mulFold64(readU64(p, ui(l)-4*8)^(key64_048+seed), readU64(p, ui(l)-3*8)^(key64_056-seed))
		} // 32
		acc += mulFold64(readU64(p, 0*8)^(key64_000+seed), readU64(p, 1*8)^(key64_008-seed))
		acc += mulFold64(readU64(p, ui(l)-2*8)^(key64_016+seed), readU64(p, ui(l)-1*8)^(key64_024-seed))

		return xxh3Avalanche(acc)

	case l <= 240:
		acc = u64(l) * prime64_1

		acc += mulFold64(readU64(p, 0*16+0)^(key64_000+seed), readU64(p, 0*16+8)^(key64_008-seed))
		acc += mulFold64(readU64(p, 1*16+0)^(key64_016+seed), readU64(p, 1*16+8)^(key64_024-seed))
		acc += mulFold64(readU64(p, 2*16+0)^(key64_032+seed), readU64(p, 2*16+8)^(key64_040-seed))
		acc += mulFold64(readU64(p, 3*16+0)^(key64_048+seed), readU64(p, 3*16+8)^(key64_056-seed))
		acc += mulFold64(readU64(p, 4*16+0)^(key64_064+seed), readU64(p, 4*16+8)^(key64_072-seed))
		acc += mulFold64(readU64(p, 5*16+0)^(key64_080+seed), readU64(p, 5*16+8)^(key64_088-seed))
		acc += mulFold64(readU64(p, 6*16+0)^(key64_096+seed), readU64(p, 6*16+8)^(key64_104-seed))
		acc += mulFold64(readU64(p, 7*16+0)^(key64_112+seed), readU64(p, 7*16+8)^(key64_120-seed))

		// avalanche
		acc = xxh3Avalanche(acc)

		// trailing groups after 128
		top := ui(l) &^ 15
		for i := ui(8 * 16); i < top; i += 16 {
			acc += mulFold64(readU64(p, i+0)^(readU64(key, i-125)+seed), readU64(p, i+8)^(readU64(key, i-117)-seed))
		}

		// last 16 bytes
		acc += mulFold64(readU64(p, ui(l)-16)^(key64_119+seed), readU64(p, ui(l)-8)^(key64_127-seed))

		return xxh3Avalanche(acc)

	default:
		acc = u64(l) * prime64_1

		secret := key
		if seed != 0 {
			secret = ptr(&[secretSize]byte{})
			initSecret(secret, seed)
		}

		accs := [8]u64{
			prime32_3, prime64_1, prime64_2, prime64_3,
			prime64_4, prime32_2, prime64_5, prime32_1,
		}

		if hasAVX512 && l >= avx512Switch {
			accumAVX512(&accs, p, secret, u64(l))
		} else if hasAVX2 {
			accumAVX2(&accs, p, secret, u64(l))
		} else if hasSSE2 {
			accumSSE(&accs, p, secret, u64(l))
		} else {
			accumScalarSeed(&accs, p, secret, u64(l))
		}

		// merge accs
		acc += mulFold64(accs[0]^readU64(secret, 11), accs[1]^readU64(secret, 19))
		acc += mulFold64(accs[2]^readU64(secret, 27), accs[3]^readU64(secret, 35))
		acc += mulFold64(accs[4]^readU64(secret, 43), accs[5]^readU64(secret, 51))
		acc += mulFold64(accs[6]^readU64(secret, 59), accs[7]^readU64(secret, 67))

		return xxh3Avalanche(acc)
	}
}