[U-Boot] [PATCH V2 1/3] memcpy: copy one word at a time if possible
Peter Tyser
ptyser at xes-inc.com
Thu Oct 8 17:12:46 CEST 2009
On Thu, 2009-10-08 at 13:30 +0200, Alessandro Rubini wrote:
> From: Alessandro Rubini <rubini at unipv.it>
>
> Signed-off-by: Alessandro Rubini <rubini at unipv.it>
> Acked-by: Andrea Gallo <andrea.gallo at stericsson.com>
> ---
> lib_generic/string.c | 17 +++++++++++++----
> 1 files changed, 13 insertions(+), 4 deletions(-)
>
> diff --git a/lib_generic/string.c b/lib_generic/string.c
> index 181eda6..9911941 100644
> --- a/lib_generic/string.c
> +++ b/lib_generic/string.c
> @@ -446,12 +446,21 @@ char * bcopy(const char * src, char * dest, int count)
> * You should not use this function to access IO space, use memcpy_toio()
> * or memcpy_fromio() instead.
> */
> -void * memcpy(void * dest,const void *src,size_t count)
> +void * memcpy(void *dest, const void *src, size_t count)
> {
> - char *tmp = (char *) dest, *s = (char *) src;
> + char *d8 = (char *)dest, *s8 = (char *)src;
> + unsigned long *dl = (unsigned long *)dest, *sl = (unsigned long *)src;
>
> + /* if all data is aligned (common case), copy a word at a time */
> + if ( (((int)dest | (int)src | count) & (sizeof(long) - 1)) == 0) {
> + count /= sizeof(unsigned long);
> + while (count--)
> + *dl++ = *sl++;
> + return dest;
> + }
> + /* else, use 1-byte copy */
> while (count--)
> - *tmp++ = *s++;
> + *d8++ = *s8++;
>
> return dest;
> }
Hi Alessandro,
No interest in the suggestion to not require count to be an exact
multiple of 4/8? I don't think it would be that hard to update the
logic accordingly and this would let your code be utilized much more
often, especially if/when we run on a 64-bit machine. Conceptually it
seems like a cleaner implementation too, but that's probably just my
preference:)
Best,
Peter
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