From: Mark Jackson <mpfj-list@mimc.co.uk>
To: u-boot@lists.denx.de
Subject: [U-Boot] [PATCH V2 1/3] memcpy: copy one word at a time if possible
Date: Fri, 09 Oct 2009 11:11:16 +0100 [thread overview]
Message-ID: <4ACF0C44.9040101@mimc.co.uk> (raw)
In-Reply-To: <4ACEBF19.4010902@free.fr>
Chris Moore wrote:
> I agree wholeheartedly with the idea but shouldn't it be more like this
> (untested) code :
>
> void * memcpy(void *dest, const void *src, size_t count)
>
> {
> char *d8, *s8;
> unsigned long *dl = dest, *sl = src;
>
In here, would it be overkill to add byte copying until data is aligned, and
then fall into the aligned copy code.
In that case, you'd still gain a speed increase if you're starting at an unaligned
address ?
> /* while all data is aligned (common case), copy multiple bytes at a time */
> if ( (((int)(long)dest | (int)(long)src) & (sizeof(*dl) - 1)) == 0) {
> while (count >= sizeof(*dl)) {
> *dl++ = *sl++;
> count -= sizeof(*dl);
> }
> }
>
> d8 = (char *)dl;
> s8 = (char *)sl;
>
> /* copy any remaining data byte by byte */
> while (count--)
> *d8++ = *s8++;
>
> return dest;
> }
Regards
Mark
next prev parent reply other threads:[~2009-10-09 10:11 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-10-08 11:29 [U-Boot] [PATCH V2 0/3] make memcpy and memset faster Alessandro Rubini
2009-10-08 11:30 ` [U-Boot] [PATCH V2 1/3] memcpy: copy one word at a time if possible Alessandro Rubini
2009-10-08 15:12 ` Peter Tyser
2009-10-08 16:00 ` Alessandro Rubini
2009-10-08 16:30 ` Peter Tyser
2009-10-08 18:23 ` Alessandro Rubini
2009-10-08 19:09 ` Peter Tyser
2009-10-08 19:17 ` Alessandro Rubini
2009-10-08 20:40 ` Wolfgang Denk
2009-10-08 20:47 ` Wolfgang Denk
2009-10-08 19:14 ` Mike Frysinger
2009-10-08 20:44 ` Wolfgang Denk
2009-10-09 4:42 ` Chris Moore
2009-10-09 10:11 ` Mark Jackson [this message]
2009-10-09 10:26 ` Mike Frysinger
2009-10-11 7:06 ` Chris Moore
2009-10-09 11:12 ` Wolfgang Denk
2009-10-08 11:30 ` [U-Boot] [PATCH V2 2/3] memset: fill " Alessandro Rubini
2009-10-08 20:46 ` Wolfgang Denk
2009-10-08 11:30 ` [U-Boot] [PATCH V2 3/3] lcd: remove '#if 0' 32-bit scroll, now memcpy does it Alessandro Rubini
2009-11-22 22:34 ` Wolfgang Denk
2009-11-24 23:04 ` Anatolij Gustschin
2009-10-08 20:36 ` [U-Boot] [PATCH V2 0/3] make memcpy and memset faster Wolfgang Denk
2009-10-08 21:30 ` Mike Frysinger
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