1 files changed, 104 insertions, 0 deletions
diff --git a/src/hash/maphash/maphash_purego.go b/src/hash/maphash/maphash_purego.go
new file mode 100644
index 0000000..d49a44a
--- /dev/null
+++ b/src/hash/maphash/maphash_purego.go
@@ -0,0 +1,104 @@
+// Copyright 2023 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.
+
+//go:build purego
+
+package maphash
+
+import (
+	"crypto/rand"
+	"math/bits"
+)
+
+func rthash(buf []byte, seed uint64) uint64 {
+	if len(buf) == 0 {
+		return seed
+	}
+	return wyhash(buf, seed, uint64(len(buf)))
+}
+
+func rthashString(s string, state uint64) uint64 {
+	return rthash([]byte(s), state)
+}
+
+func randUint64() uint64 {
+	buf := make([]byte, 8)
+	_, _ = rand.Read(buf)
+	return leUint64(buf)
+}
+
+// This is a port of wyhash implementation in runtime/hash64.go,
+// without using unsafe for purego.
+
+const (
+	m1 = 0xa0761d6478bd642f
+	m2 = 0xe7037ed1a0b428db
+	m3 = 0x8ebc6af09c88c6e3
+	m4 = 0x589965cc75374cc3
+	m5 = 0x1d8e4e27c47d124f
+)
+
+func wyhash(key []byte, seed, len uint64) uint64 {
+	p := key
+	i := len
+	var a, b uint64
+	seed ^= m1
+
+	if i > 16 {
+		if i > 48 {
+			seed1 := seed
+			seed2 := seed
+			for ; i > 48; i -= 48 {
+				seed = mix(r8(p)^m2, r8(p[8:])^seed)
+				seed1 = mix(r8(p[16:])^m3, r8(p[24:])^seed1)
+				seed2 = mix(r8(p[32:])^m4, r8(p[40:])^seed2)
+				p = p[48:]
+			}
+			seed ^= seed1 ^ seed2
+		}
+		for ; i > 16; i -= 16 {
+			seed = mix(r8(p)^m2, r8(p[8:])^seed)
+			p = p[16:]
+		}
+	}
+	switch {
+	case i == 0:
+		return seed
+	case i < 4:
+		a = r3(p, i)
+	default:
+		n := (i >> 3) << 2
+		a = r4(p)<<32 | r4(p[n:])
+		b = r4(p[i-4:])<<32 | r4(p[i-4-n:])
+	}
+	return mix(m5^len, mix(a^m2, b^seed))
+}
+
+func r3(p []byte, k uint64) uint64 {
+	return (uint64(p[0]) << 16) | (uint64(p[k>>1]) << 8) | uint64(p[k-1])
+}
+
+func r4(p []byte) uint64 {
+	return uint64(leUint32(p))
+}
+
+func r8(p []byte) uint64 {
+	return leUint64(p)
+}
+
+func mix(a, b uint64) uint64 {
+	hi, lo := bits.Mul64(a, b)
+	return hi ^ lo
+}
+
+func leUint32(b []byte) uint32 {
+	_ = b[3] // bounds check hint to compiler; see golang.org/issue/14808
+	return uint32(b[0]) | uint32(b[1])<<8 | uint32(b[2])<<16 | uint32(b[3])<<24
+}
+
+func leUint64(b []byte) uint64 {
+	_ = b[7] // bounds check hint to compiler; see golang.org/issue/14808
+	return uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24 |
+		uint64(b[4])<<32 | uint64(b[5])<<40 | uint64(b[6])<<48 | uint64(b[7])<<56
+}