From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Frysinger Date: Wed, 7 Oct 2009 13:04:46 -0400 Subject: [U-Boot] [PATCH 1/3] memcpy: use 32-bit copies if possible In-Reply-To: <1254926119.24664.4957.camel@localhost.localdomain> References: <1254926119.24664.4957.camel@localhost.localdomain> Message-ID: <200910071304.48628.vapier@gentoo.org> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de On Wednesday 07 October 2009 10:35:19 Peter Tyser wrote: > > --- a/lib_generic/string.c > > +++ b/lib_generic/string.c > > @@ -449,7 +449,16 @@ char * bcopy(const char * src, char * dest, int > > count) void * memcpy(void * dest,const void *src,size_t count) > > { > > char *tmp = (char *) dest, *s = (char *) src; > > + u32 *d32 = (u32 *)dest, *s32 = (u32 *) src; > > > > + /* if both are aligned, use 32-bit copy */ > > + if ( (((int)dest & 3) | ((int)src & 3) | (count & 3)) == 0 ) { > > + count /= 4; > > + while (count--) > > + *d32++ = *s32++; > > + return dest; > > + } > > + /* else, use 1-byte copy */ > > while (count--) > > *tmp++ = *s++; > > If we're adding this logic, what about adding it such that: > > if (src/dest are 32-bit aligned and count > 3) { > perform 32-bit copies till count <= 3 > } > perform remaining 8-bit copies till count == 0 > > You'd still get the performance boost but not have the requirement that > count is evenly divisible by 4. You could do byte copies before the > 32-bit copies to align the src/dest in some cases, but that might be > overkill... i thought the same but didnt feel like sending out another e-mail ;) -mike -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: application/pgp-signature Size: 836 bytes Desc: This is a digitally signed message part. Url : http://lists.denx.de/pipermail/u-boot/attachments/20091007/10ed4a62/attachment.pgp