1 files changed, 92 insertions, 0 deletions
diff --git a/src/runtime/hash64.go b/src/runtime/hash64.go
new file mode 100644
index 0000000..2864a4b
--- /dev/null
+++ b/src/runtime/hash64.go
@@ -0,0 +1,92 @@
+// 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 || loong64 || mips64 || mips64le || ppc64 || ppc64le || riscv64 || s390x || wasm
+
+package runtime
+
+import (
+	"runtime/internal/math"
+	"unsafe"
+)
+
+const (
+	m1 = 0xa0761d6478bd642f
+	m2 = 0xe7037ed1a0b428db
+	m3 = 0x8ebc6af09c88c6e3
+	m4 = 0x589965cc75374cc3
+	m5 = 0x1d8e4e27c47d124f
+)
+
+func memhashFallback(p unsafe.Pointer, seed, s uintptr) uintptr {
+	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))
+}
+
+func memhash32Fallback(p unsafe.Pointer, seed uintptr) uintptr {
+	a := r4(p)
+	return mix(m5^4, mix(a^m2, a^seed^hashkey[0]^m1))
+}
+
+func memhash64Fallback(p unsafe.Pointer, seed uintptr) uintptr {
+	a := r8(p)
+	return mix(m5^8, mix(a^m2, a^seed^hashkey[0]^m1))
+}
+
+func mix(a, b uintptr) uintptr {
+	hi, lo := math.Mul64(uint64(a), uint64(b))
+	return uintptr(hi ^ lo)
+}
+
+func r4(p unsafe.Pointer) uintptr {
+	return uintptr(readUnaligned32(p))
+}
+
+func r8(p unsafe.Pointer) uintptr {
+	return uintptr(readUnaligned64(p))
+}