freebsd-dev/lib/libc/i386/string/memset.S
2002-03-23 02:44:19 +00:00

90 lines
2.7 KiB
ArmAsm

/*
* Copyright (c) 1993 Winning Strategies, Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by Winning Strategies, Inc.
* 4. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <machine/asm.h>
__FBSDID("$FreeBSD$");
/*
* memset(void *b, int c, size_t len)
* write len bytes of value c (converted to an unsigned char) to
* the string b.
*
* Written by:
* J.T. Conklin (jtc@wimsey.com), Winning Strategies, Inc.
*/
ENTRY(memset)
pushl %edi
pushl %ebx
movl 12(%esp),%edi
movzbl 16(%esp),%eax /* unsigned char, zero extend */
movl 20(%esp),%ecx
pushl %edi /* push address of buffer */
cld /* set fill direction forward */
/*
* if the string is too short, it's really not worth the overhead
* of aligning to word boundries, etc. So we jump to a plain
* unaligned set.
*/
cmpl $0x0f,%ecx
jle L1
movb %al,%ah /* copy char to all bytes in word */
movl %eax,%edx
sall $16,%eax
orl %edx,%eax
movl %edi,%edx /* compute misalignment */
negl %edx
andl $3,%edx
movl %ecx,%ebx
subl %edx,%ebx
movl %edx,%ecx /* set until word aligned */
rep
stosb
movl %ebx,%ecx
shrl $2,%ecx /* set by words */
rep
stosl
movl %ebx,%ecx /* set remainder by bytes */
andl $3,%ecx
L1: rep
stosb
popl %eax /* pop address of buffer */
popl %ebx
popl %edi
ret