Merge "libc: memset: improve performance by avoiding single byte writes" into integration
diff --git a/lib/libc/memset.c b/lib/libc/memset.c
index d8007d8..f9dd4c5 100644
--- a/lib/libc/memset.c
+++ b/lib/libc/memset.c
@@ -1,18 +1,48 @@
/*
- * Copyright (c) 2013-2019, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2013-2020, ARM Limited and Contributors. All rights reserved.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
#include <stddef.h>
#include <string.h>
+#include <stdint.h>
void *memset(void *dst, int val, size_t count)
{
char *ptr = dst;
+ uint64_t *ptr64;
+ uint64_t fill = (unsigned char)val;
- while (count--)
+ /* Simplify code below by making sure we write at least one byte. */
+ if (count == 0) {
+ return dst;
+ }
+
+ /* Handle the first part, until the pointer becomes 64-bit aligned. */
+ while (((uintptr_t)ptr & 7)) {
+ *ptr++ = val;
+ if (--count == 0) {
+ return dst;
+ }
+ }
+
+ /* Duplicate the fill byte to the rest of the 64-bit word. */
+ fill |= fill << 8;
+ fill |= fill << 16;
+ fill |= fill << 32;
+
+ /* Use 64-bit writes for as long as possible. */
+ ptr64 = (void *)ptr;
+ for (; count >= 8; count -= 8) {
+ *ptr64++ = fill;
+ }
+
+ /* Handle the remaining part byte-per-byte. */
+ ptr = (void *)ptr64;
+ while (count--) {
*ptr++ = val;
+ }
return dst;
}