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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

  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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