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author | Indrajith K L | 2022-12-03 17:00:20 +0530 |
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committer | Indrajith K L | 2022-12-03 17:00:20 +0530 |
commit | f5c4671bfbad96bf346bd7e9a21fc4317b4959df (patch) | |
tree | 2764fc62da58f2ba8da7ed341643fc359873142f /v_windows/v/vlib/hash/wyhash.v | |
download | cli-tools-windows-f5c4671bfbad96bf346bd7e9a21fc4317b4959df.tar.gz cli-tools-windows-f5c4671bfbad96bf346bd7e9a21fc4317b4959df.tar.bz2 cli-tools-windows-f5c4671bfbad96bf346bd7e9a21fc4317b4959df.zip |
Diffstat (limited to 'v_windows/v/vlib/hash/wyhash.v')
-rw-r--r-- | v_windows/v/vlib/hash/wyhash.v | 72 |
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) + } +} |