github.com/bytedance/gopkg@v0.0.0-20240514070511-01b2cbcf35e1/util/xxhash3/util.go (about)

     1  // Copyright 2021 ByteDance Inc.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  // Package xxhash3 implements https://github.com/Cyan4973/xxHash/blob/dev/xxhash.h
    16  package xxhash3
    17  
    18  import (
    19  	"math/bits"
    20  	"unsafe"
    21  
    22  	"golang.org/x/sys/cpu"
    23  )
    24  
    25  var (
    26  	avx2        = cpu.X86.HasAVX2
    27  	sse2        = cpu.X86.HasSSE2
    28  	hashfunc    = [2]func(unsafe.Pointer, int) uint64{xxh3HashSmall, xxh3HashLarge}
    29  	hashfunc128 = [2]func(unsafe.Pointer, int) [2]uint64{xxh3HashSmall128, xxh3HashLarge128}
    30  )
    31  
    32  type funcUnsafe int
    33  
    34  const (
    35  	hashSmall funcUnsafe = iota
    36  	hashLarge
    37  )
    38  
    39  func mix(a, b uint64) uint64 {
    40  	hi, lo := bits.Mul64(a, b)
    41  	return hi ^ lo
    42  }
    43  func xxh3RRMXMX(h64 uint64, length uint64) uint64 {
    44  	h64 ^= bits.RotateLeft64(h64, 49) ^ bits.RotateLeft64(h64, 24)
    45  	h64 *= 0x9fb21c651e98df25
    46  	h64 ^= (h64 >> 35) + length
    47  	h64 *= 0x9fb21c651e98df25
    48  	h64 ^= (h64 >> 28)
    49  	return h64
    50  }
    51  
    52  func xxh64Avalanche(h64 uint64) uint64 {
    53  	h64 *= prime64_2
    54  	h64 ^= h64 >> 29
    55  	h64 *= prime64_3
    56  	h64 ^= h64 >> 32
    57  	return h64
    58  }
    59  
    60  func xxh3Avalanche(x uint64) uint64 {
    61  	x ^= x >> 37
    62  	x *= 0x165667919e3779f9
    63  	x ^= x >> 32
    64  	return x
    65  }