[U-Boot] [PATCH 1/3] memcpy: use 32-bit copies if possible

[Mike Frysinger]

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
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