On Wed, Sep 5, 2018 at 2:08 PM Guo Ren <ren_guo@xxxxxxxxx> wrote:
> --- /dev/null
> +++ b/arch/csky/abiv1/memset.c
> @@ -0,0 +1,38 @@
> +// SPDX-License-Identifier: GPL-2.0
> +// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
> +#include <linux/types.h>
> +
> +void *memset(void *dest, int c, size_t l)
> +{
> + char *d = dest;
> + int ch = c;
> + int tmp;
> +
> + if ((long)d & 0x3)
> + while (l--) *d++ = ch;
> + else {
> + ch &= 0xff;
> + tmp = (ch | ch << 8 | ch << 16 | ch << 24);
> +
> + while (l >= 16) {
> + *(((long *)d)) = tmp;
> + *(((long *)d)+1) = tmp;
> + *(((long *)d)+2) = tmp;
> + *(((long *)d)+3) = tmp;
> + l -= 16;
> + d += 16;
> + }
> +
> + while (l > 3) {
> + *(((long *)d)) = tmp;
> + d = d + 4;
> + l -= 4;
> + }
> +
> + while (l) {
> + *d++ = ch;
> + l--;
> + }
> + }
> + return dest;
> +}
I see that we have a trivial memset() implementation in lib/string.c, but yours
seems to be better optimized. Where did you get it from? Is this a version
that works particularly well on C-Sky, or is this a generic optimized memset
that others could use as well? In the latter case, we could add it to
lib/string.c and let architectures select it in place of the triivial version.
Arnd
