Messages in this thread | | | Subject | Re: [PATCH 1/8] lib/sort: Heapsort implementation of sort() | From | Andreas Gruenbacher <> | Date | Tue, 01 Feb 2005 18:54:18 +0100 |
| |
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 <agruen@suse.de> SUSE Labs, SUSE LINUX GMBH
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |