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[PATCH] Improve bzero performance
- From: "Wilco Dijkstra" <wdijkstr at arm dot com>
- To: <libc-alpha at sourceware dot org>
- Date: Mon, 12 Jan 2015 15:11:47 -0000
- Subject: [PATCH] Improve bzero performance
- Authentication-results: sourceware.org; auth=none
Rather than using a C implementation of memset, directly call memset, which typically has a much
faster optimized implementation.
ChangeLog:
2015-01-12 Wilco Dijkstra wdijkstr@arm.com
* string/bzero.c (__bzero): Call memset for performance.
---
string/bzero.c | 58 +++-------------------------------------------------------
1 file changed, 3 insertions(+), 55 deletions(-)
diff --git a/string/bzero.c b/string/bzero.c
index 9c220b9..f1a0584 100644
--- a/string/bzero.c
+++ b/string/bzero.c
@@ -16,67 +16,15 @@
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
+#include <stddef.h>
#include <string.h>
-#include <memcopy.h>
#undef __bzero
/* Set N bytes of S to 0. */
void
-__bzero (s, len)
- void *s;
- size_t len;
+__bzero (void *s, size_t len)
{
- long int dstp = (long int) s;
- const op_t zero = 0;
-
- if (len >= 8)
- {
- size_t xlen;
-
- /* There are at least some bytes to zero. No need to test
- for LEN == 0 in this alignment loop. */
- while (dstp % OPSIZ != 0)
- {
- ((byte *) dstp)[0] = 0;
- dstp += 1;
- len -= 1;
- }
-
- /* Write 8 op_t per iteration until less than 8 op_t remain. */
- xlen = len / (OPSIZ * 8);
- while (xlen != 0)
- {
- ((op_t *) dstp)[0] = zero;
- ((op_t *) dstp)[1] = zero;
- ((op_t *) dstp)[2] = zero;
- ((op_t *) dstp)[3] = zero;
- ((op_t *) dstp)[4] = zero;
- ((op_t *) dstp)[5] = zero;
- ((op_t *) dstp)[6] = zero;
- ((op_t *) dstp)[7] = zero;
- dstp += 8 * OPSIZ;
- xlen -= 1;
- }
- len %= OPSIZ * 8;
-
- /* Write 1 op_t per iteration until less than op_t remain. */
- xlen = len / OPSIZ;
- while (xlen != 0)
- {
- ((op_t *) dstp)[0] = zero;
- dstp += OPSIZ;
- xlen -= 1;
- }
- len %= OPSIZ;
- }
-
- /* Write the last few bytes. */
- while (len != 0)
- {
- ((byte *) dstp)[0] = 0;
- dstp += 1;
- len -= 1;
- }
+ memset (s, '\0', len);
}
weak_alias (__bzero, bzero)
--
1.9.1