On Mon, 2005-01-31 at 18:30, Paulo Marques wrote:
> Andreas Gruenbacher wrote:
> > [...]
> >
> > static inline void swap(void *a, void *b, int size)
> > {
> > if (size % sizeof(long)) {
> > char t;
> > do {
> > t = *(char *)a;
> > *(char *)a++ = *(char *)b;
> > *(char *)b++ = t;
> > } while (--size > 0);
> > } else {
> > long t;
> > do {
> > t = *(long *)a;
> > *(long *)a = *(long *)b;
> > *(long *)b = t;
> > size -= sizeof(long);
> > } while (size > sizeof(long));
>
> You forgot to increment a and b, and this should be "while (size);", no?
Correct, yes.
> Or better yet,
>
> static inline void swap(void *a, void *b, int size)
> {
> long tl;
> char t;
>
> while (size >= sizeof(long)) {
> tl = *(long *)a;
> *(long *)a = *(long *)b;
> *(long *)b = tl;
> a += sizeof(long);
> b += sizeof(long);
> size -= sizeof(long);
> }
> while (size) {
> t = *(char *)a;
> *(char *)a++ = *(char *)b;
> *(char *)b++ = t;
> size--;
> }
> }
>
> This works better if the size is not a multiple of sizeof(long), but is
> bigger than a long.
In case size is not a multiple of sizeof(long) here, you'll have
unaligned memory accesses most of the time anyway, so it probably
doesn't really matter.
Thanks,
--
Andreas Gruenbacher <[EMAIL PROTECTED]>
SUSE Labs, SUSE LINUX GMBH
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