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Merge "libc: memset: improve performance by avoiding single byte writes" into integration

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Mark Dykes 2020-09-09 18:36:08 +00:00 committed by TrustedFirmware Code Review
parent 7fbb3dbac4 75fab6496e
commit 0b96df769f
1 changed files with 32 additions and 2 deletions
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34
lib/libc/memset.c
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@ -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;
}