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/* memset/bzero -- set memory area to CH/0
Highly optimized version for ix86, x>=5.
Copyright (C) 1996, 1997 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Torbjorn Granlund, <tege@matematik.su.se>
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If not,
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
#include <sysdep.h>
#include "asm-syntax.h"
/*
INPUT PARAMETERS:
(memset) (bzero)
dst (sp + 4) dst (sp + 4)
ch (sp + 8) len (sp + 8)
len (sp + 12)
*/
.text
ENTRY (memset)
pushl %edi
movl 8(%esp), %edi /* destination pointer */
#ifdef memset
xorl %eax, %eax /* we fill with 0 */
movl 12(%esp), %edx /* size (in 8-bit words) */
#else
movb 12(%esp), %al /* use CH to fill */
movl 16(%esp), %edx /* size (in 8-bit words) */
movb %al, %ah
movl %eax, %ecx
shll $16, %eax
movw %cx, %ax
#endif
cld
/* If less than 36 bytes to write, skip tricky code (it wouldn't work). */
cmpl $36, %edx
movl %edx, %ecx /* needed when branch is taken! */
jl L(2)
/* First write 0-3 bytes to make the pointer 32-bit aligned. */
movl %edi, %ecx /* Copy ptr to ecx... */
negl %ecx /* ...and negate that and... */
andl $3, %ecx /* ...mask to get byte count. */
subl %ecx, %edx /* adjust global byte count */
rep
stosb
subl $32, %edx /* offset count for unrolled loop */
movl (%edi), %ecx /* Fetch destination cache line */
.align 2, 0x90 /* supply 0x90 for broken assemblers */
L(1): movl 28(%edi), %ecx /* allocate cache line for destination */
subl $32, %edx /* decr loop count */
movl %eax, 0(%edi) /* store words pairwise */
movl %eax, 4(%edi)
movl %eax, 8(%edi)
movl %eax, 12(%edi)
movl %eax, 16(%edi)
movl %eax, 20(%edi)
movl %eax, 24(%edi)
movl %eax, 28(%edi)
leal 32(%edi), %edi /* update destination pointer */
jge L(1)
leal 32(%edx), %ecx /* reset offset count */
/* Write last 0-7 full 32-bit words (up to 8 words if loop was skipped). */
L(2): shrl $2, %ecx /* convert byte count to longword count */
rep
stosl
/* Finally write the last 0-3 bytes. */
movl %edx, %ecx
andl $3, %ecx
rep
stosb
/* Load result (only if used as memset). */
#ifndef memset
movl 8(%esp), %eax
#endif
popl %edi
ret
END (memset)
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