1 files changed, 72 insertions, 0 deletions
diff --git a/v_windows/v/vlib/hash/wyhash.v b/v_windows/v/vlib/hash/wyhash.v
new file mode 100644
index 0000000..fb438a1
--- /dev/null
+++ b/v_windows/v/vlib/hash/wyhash.v
@@ -0,0 +1,72 @@
+// Copyright (c) 2019-2021 Alexander Medvednikov. All rights reserved.
+// Use of this source code is governed by an MIT license
+// that can be found in the LICENSE file.
+//
+// this is an implementation of wyhash v4
+// from https://github.com/wangyi-fudan/wyhash
+//
+// TODO: use u128 once implemented
+// currently the C version performs slightly better
+// because it uses 128 bit int when available and
+// branch prediction hints. the C version will be
+// removed once the perfomance is matched.
+// you can test performance by running:
+// `v run cmd/tools/bench/wyhash.v`
+// try running with and without the `-prod` flag
+module hash
+
+const (
+	wyp0 = u64(0xa0761d6478bd642f)
+	wyp1 = u64(0xe7037ed1a0b428db)
+	wyp2 = u64(0x8ebc6af09c88c6e3)
+	wyp3 = u64(0x589965cc75374cc3)
+	wyp4 = u64(0x1d8e4e27c47d124f)
+)
+
+[inline]
+fn wyrotr(v u64, k u32) u64 {
+	return (v >> k) | (v << (64 - k))
+}
+
+[inline]
+pub fn wymum(a u64, b u64) u64 {
+	/*
+	mut r := u128(a)
+	r = r*b
+	return (r>>64)^r
+	*/
+	mask32 := u32(4294967295)
+	x0 := a & mask32
+	x1 := a >> 32
+	y0 := b & mask32
+	y1 := b >> 32
+	w0 := x0 * y0
+	t := x1 * y0 + (w0 >> 32)
+	mut w1 := t & mask32
+	w2 := t >> 32
+	w1 += x0 * y1
+	hi := x1 * y1 + w2 + (w1 >> 32)
+	lo := a * b
+	return hi ^ lo
+}
+
+[inline]
+fn wyr3(p &byte, k u64) u64 {
+	unsafe {
+		return (u64(p[0]) << 16) | (u64(p[k >> 1]) << 8) | u64(p[k - 1])
+	}
+}
+
+[inline]
+fn wyr4(p &byte) u64 {
+	unsafe {
+		return u32(p[0]) | (u32(p[1]) << u32(8)) | (u32(p[2]) << u32(16)) | (u32(p[3]) << u32(24))
+	}
+}
+
+[inline]
+fn wyr8(p &byte) u64 {
+	unsafe {
+		return u64(p[0]) | (u64(p[1]) << 8) | (u64(p[2]) << 16) | (u64(p[3]) << 24) | (u64(p[4]) << 32) | (u64(p[5]) << 40) | (u64(p[6]) << 48) | (u64(p[7]) << 56)
+	}
+}