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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-28 13:14:23 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-28 13:14:23 +0000 |
commit | 73df946d56c74384511a194dd01dbe099584fd1a (patch) | |
tree | fd0bcea490dd81327ddfbb31e215439672c9a068 /src/runtime/hash32.go | |
parent | Initial commit. (diff) | |
download | golang-1.16-73df946d56c74384511a194dd01dbe099584fd1a.tar.xz golang-1.16-73df946d56c74384511a194dd01dbe099584fd1a.zip |
Adding upstream version 1.16.10.upstream/1.16.10upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r-- | src/runtime/hash32.go | 112 |
1 files changed, 112 insertions, 0 deletions
diff --git a/src/runtime/hash32.go b/src/runtime/hash32.go new file mode 100644 index 0000000..966f70e --- /dev/null +++ b/src/runtime/hash32.go @@ -0,0 +1,112 @@ +// 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 +// xxhash: https://code.google.com/p/xxhash/ +// cityhash: https://code.google.com/p/cityhash/ + +// +build 386 arm mips mipsle + +package runtime + +import "unsafe" + +const ( + // Constants for multiplication: four random odd 32-bit numbers. + m1 = 3168982561 + m2 = 3339683297 + m3 = 832293441 + m4 = 2336365089 +) + +func memhashFallback(p unsafe.Pointer, seed, s uintptr) uintptr { + h := uint32(seed + s*hashkey[0]) +tail: + switch { + case s == 0: + case s < 4: + h ^= uint32(*(*byte)(p)) + h ^= uint32(*(*byte)(add(p, s>>1))) << 8 + h ^= uint32(*(*byte)(add(p, s-1))) << 16 + h = rotl_15(h*m1) * m2 + case s == 4: + h ^= readUnaligned32(p) + h = rotl_15(h*m1) * m2 + case s <= 8: + h ^= readUnaligned32(p) + h = rotl_15(h*m1) * m2 + h ^= readUnaligned32(add(p, s-4)) + h = rotl_15(h*m1) * m2 + case s <= 16: + h ^= readUnaligned32(p) + h = rotl_15(h*m1) * m2 + h ^= readUnaligned32(add(p, 4)) + h = rotl_15(h*m1) * m2 + h ^= readUnaligned32(add(p, s-8)) + h = rotl_15(h*m1) * m2 + h ^= readUnaligned32(add(p, s-4)) + h = rotl_15(h*m1) * m2 + default: + v1 := h + v2 := uint32(seed * hashkey[1]) + v3 := uint32(seed * hashkey[2]) + v4 := uint32(seed * hashkey[3]) + for s >= 16 { + v1 ^= readUnaligned32(p) + v1 = rotl_15(v1*m1) * m2 + p = add(p, 4) + v2 ^= readUnaligned32(p) + v2 = rotl_15(v2*m2) * m3 + p = add(p, 4) + v3 ^= readUnaligned32(p) + v3 = rotl_15(v3*m3) * m4 + p = add(p, 4) + v4 ^= readUnaligned32(p) + v4 = rotl_15(v4*m4) * m1 + p = add(p, 4) + s -= 16 + } + h = v1 ^ v2 ^ v3 ^ v4 + goto tail + } + h ^= h >> 17 + h *= m3 + h ^= h >> 13 + h *= m4 + h ^= h >> 16 + return uintptr(h) +} + +func memhash32Fallback(p unsafe.Pointer, seed uintptr) uintptr { + h := uint32(seed + 4*hashkey[0]) + h ^= readUnaligned32(p) + h = rotl_15(h*m1) * m2 + h ^= h >> 17 + h *= m3 + h ^= h >> 13 + h *= m4 + h ^= h >> 16 + return uintptr(h) +} + +func memhash64Fallback(p unsafe.Pointer, seed uintptr) uintptr { + h := uint32(seed + 8*hashkey[0]) + h ^= readUnaligned32(p) + h = rotl_15(h*m1) * m2 + h ^= readUnaligned32(add(p, 4)) + h = rotl_15(h*m1) * m2 + h ^= h >> 17 + h *= m3 + h ^= h >> 13 + h *= m4 + h ^= h >> 16 + return uintptr(h) +} + +// Note: in order to get the compiler to issue rotl instructions, we +// need to constant fold the shift amount by hand. +// TODO: convince the compiler to issue rotl instructions after inlining. +func rotl_15(x uint32) uint32 { + return (x << 15) | (x >> (32 - 15)) +} |