You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: hash64.go
    path of file: ./repos/gccrs/libgo/go/runtime
    
    the code of the file until where you have to start completion: // Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Hashing algorithm inspired by
// wyhash: https://github.com/wangyi-fudan/wyhash

//go:build amd64 || arm64 || mips64 || mips64le || ppc64 || ppc64le || riscv64 || s390x || wasm || alpha || arm64be || ia64 || sparc64

package runtime

import (
	"runtime/internal/math"
	"unsafe"
)

// For gccgo, use go:linkname to export compiler-called functions.
//
//go:linkname memhash

const (
	m1 = 0xa0761d6478bd642f
	m2 = 0xe7037ed1a0b428db
	m3 = 0x8ebc6af09c88c6e3
	m4 = 0x589965cc75374cc3
	m5 = 0x1d8e4e27c47d124f
)

func memhash(p unsafe.Pointer, seed, s uintptr) uintptr {
	if (GOARCH == "amd64" || GOARCH == "arm64") && useAeshash {
		return 
    
func memhash(p unsafe.Pointer, seed, s uintptr) uintptr {
	if (GOARCH == "amd64" || GOARCH == "arm64") && useAeshash {
		return aeshash(p, seed, s)
	}
	var a, b uintptr
	seed ^= hashkey[0] ^ m1
	switch {
	case s == 0:
		return seed
	case s < 4:
		a = uintptr(*(*byte)(p))
		a |= uintptr(*(*byte)(add(p, s>>1))) << 8
		a |= uintptr(*(*byte)(add(p, s-1))) << 16
	case s == 4:
		a = r4(p)
		b = a
	case s < 8:
		a = r4(p)
		b = r4(add(p, s-4))
	case s == 8:
		a = r8(p)
		b = a
	case s <= 16:
		a = r8(p)
		b = r8(add(p, s-8))
	default:
		l := s
		if l > 48 {
			seed1 := seed
			seed2 := seed
			for ; l > 48; l -= 48 {
				seed = mix(r8(p)^m2, r8(add(p, 8))^seed)
				seed1 = mix(r8(add(p, 16))^m3, r8(add(p, 24))^seed1)
				seed2 = mix(r8(add(p, 32))^m4, r8(add(p, 40))^seed2)
				p = add(p, 48)
			}
			seed ^= seed1 ^ seed2
		}
		for ; l > 16; l -= 16 {
			seed = mix(r8(p)^m2, r8(add(p, 8))^seed)
			p = add(p, 16)
		}
		a = r8(add(p, l-16))
		b = r8(add(p, l-8))
	}

	return mix(m5^s, mix(a^m2, b^seed))
}