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// Copyright (c) 2019. Temple3x (temple3x@gmail.com)
//
// Use of this source code is governed by the MIT License
// that can be found in the LICENSE file.
package xorsimd
import "github.com/templexxx/cpu"
// EnableAVX512 may slow down CPU Clock (maybe not).
// TODO need more research:
// https://lemire.me/blog/2018/04/19/by-how-much-does-avx-512-slow-down-your-cpu-a-first-experiment/
var EnableAVX512 = true
// cpuFeature indicates which instruction set will be used.
var cpuFeature = getCPUFeature()
const (
avx512 = iota
avx2
sse2
generic
)
// TODO: Add ARM feature...
func getCPUFeature() int {
if hasAVX512() && EnableAVX512 {
return avx512
} else if cpu.X86.HasAVX2 {
return avx2
} else {
return sse2 // amd64 must has sse2
}
}
func hasAVX512() (ok bool) {
return cpu.X86.HasAVX512VL &&
cpu.X86.HasAVX512BW &&
cpu.X86.HasAVX512F &&
cpu.X86.HasAVX512DQ
}
// Encode encodes elements from source slice into a
// destination slice. The source and destination may overlap.
// Encode returns the number of bytes encoded, which will be the minimum of
// len(src[i]) and len(dst).
func Encode(dst []byte, src [][]byte) (n int) {
n = checkLen(dst, src)
if n == 0 {
return
}
dst = dst[:n]
for i := range src {
src[i] = src[i][:n]
}
if len(src) == 1 {
copy(dst, src[0])
return
}
encode(dst, src)
return
}
func checkLen(dst []byte, src [][]byte) int {
n := len(dst)
for i := range src {
if len(src[i]) < n {
n = len(src[i])
}
}
if n <= 0 {
return 0
}
return n
}
// Bytes XORs the bytes in a and b into a
// destination slice. The source and destination may overlap.
//
// Bytes returns the number of bytes encoded, which will be the minimum of
// len(dst), len(a), len(b).
func Bytes(dst, a, b []byte) int {
return Encode(dst, [][]byte{a, b})
}
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