mirror of
https://github.com/apache/nuttx.git
synced 2026-05-12 09:48:31 +08:00
anjiahao
4db4252a7c
Add lib_bsdmemset.c from newlib (Red Hat BSD license) which provides an optimized memset using word-aligned writes and loop unrolling for improved performance on larger buffers. Signed-off-by: anjiahao <anjiahao@xiaomi.com>
114 lines
3.2 KiB
C
114 lines
3.2 KiB
C
/****************************************************************************
|
|
* libs/libc/string/lib_bsdmemset.c
|
|
*
|
|
* SPDX-License-Identifier: BSD
|
|
* SPDX-FileCopyrightText: 1994-2009 Red Hat, Inc. All rights reserved
|
|
*
|
|
* Copyright (c) 1994-2009 Red Hat, Inc. All rights reserved.
|
|
*
|
|
* This copyrighted material is made available to anyone wishing to use,
|
|
* modify, copy, or redistribute it subject to the terms and conditions
|
|
* of the BSD License. This program is distributed in the hope that
|
|
* it will be useful, but WITHOUT ANY WARRANTY expressed or implied,
|
|
* including the implied warranties of MERCHANTABILITY or FITNESS FOR
|
|
* A PARTICULAR PURPOSE. A copy of this license is available at
|
|
* http://www.opensource.org/licenses. Any Red Hat trademarks that are
|
|
* incorporated in the source code or documentation are not subject to
|
|
* the BSD License and may only be used or replicated with the express
|
|
* permission of Red Hat, Inc.
|
|
*
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Included Files
|
|
****************************************************************************/
|
|
|
|
#include <nuttx/config.h>
|
|
#include <sys/types.h>
|
|
#include <string.h>
|
|
|
|
#include "libc.h"
|
|
|
|
/****************************************************************************
|
|
* Pre-processor Definitions
|
|
****************************************************************************/
|
|
|
|
#define LBLOCKSIZE (sizeof(long))
|
|
#define UNALIGNED(x) ((long)(x) & (LBLOCKSIZE - 1))
|
|
#define TOO_SMALL(len) ((len) < LBLOCKSIZE)
|
|
|
|
/****************************************************************************
|
|
* Public Functions
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Name: memset
|
|
****************************************************************************/
|
|
|
|
#if !defined(CONFIG_LIBC_ARCH_MEMSET) && defined(LIBC_BUILD_MEMSET)
|
|
#undef memset
|
|
no_builtin("memset")
|
|
FAR void *memset(FAR void *m, int c, size_t n)
|
|
{
|
|
FAR unsigned long *aligned_addr;
|
|
FAR char *s = (FAR char *)m;
|
|
unsigned long buffer;
|
|
int i;
|
|
|
|
/* To avoid sign extension, copy C to an unsigned variable. */
|
|
|
|
while (UNALIGNED(s))
|
|
{
|
|
if (n--)
|
|
{
|
|
*s++ = c;
|
|
}
|
|
else
|
|
{
|
|
return m;
|
|
}
|
|
}
|
|
|
|
if (!TOO_SMALL(n))
|
|
{
|
|
/* If we get this far, we know that n is large and s is word-aligned. */
|
|
|
|
aligned_addr = (FAR unsigned long *)s;
|
|
buffer = ((unsigned int)c << 8) | c;
|
|
buffer |= (buffer << 16);
|
|
for (i = 32; i < LBLOCKSIZE * 8; i <<= 1)
|
|
{
|
|
buffer = (buffer << i) | buffer;
|
|
}
|
|
|
|
/* Unroll the loop. */
|
|
|
|
while (n >= LBLOCKSIZE * 4)
|
|
{
|
|
*aligned_addr++ = buffer;
|
|
*aligned_addr++ = buffer;
|
|
*aligned_addr++ = buffer;
|
|
*aligned_addr++ = buffer;
|
|
n -= 4 * LBLOCKSIZE;
|
|
}
|
|
|
|
while (n >= LBLOCKSIZE)
|
|
{
|
|
*aligned_addr++ = buffer;
|
|
n -= LBLOCKSIZE;
|
|
}
|
|
|
|
/* Pick up the remainder with a bytewise loop. */
|
|
|
|
s = (FAR char *)aligned_addr;
|
|
}
|
|
|
|
while (n--)
|
|
{
|
|
*s++ = c;
|
|
}
|
|
|
|
return m;
|
|
}
|
|
#endif
|