rclone/backend/onedrive/quickxorhash/xor.go
LXY dc5d5de35c
onedrive: improve speed of quickxorhash
This commits ports a fast C-implementation from https://github.com/namazso/QuickXorHash

It uses new crypto/subtle code from go1.20 to avoid the use of unsafe.

Typical speedups are about 25x  when using go1.20

    goos: linux
    goarch: amd64
    cpu: Intel(R) Celeron(R) N5105 @ 2.00GHz
    QuickXorHash-Before  2.49ms   422MB/s ±11%   100.00%
    QuickXorHash-Subtle  87.9µs 11932MB/s ± 5% +2730.83% + 42.17%

Co-Author: @namazso
2023-01-26 11:50:12 +00:00

20 lines
299 B
Go

//go:build !go1.20
package quickxorhash
func xorBytes(dst, src []byte) int {
n := len(dst)
if len(src) < n {
n = len(src)
}
if n == 0 {
return 0
}
dst = dst[:n]
//src = src[:n]
src = src[:len(dst)] // remove bounds check in loop
for i := range dst {
dst[i] ^= src[i]
}
return n
}