xref: /illumos-gate/usr/src/lib/libc/i386/gen/memset.s (revision 9a70fc3b)
1/*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21
22/*
23 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
24 * Use is subject to license terms.
25 */
26
27	.file	"memset.s"
28
29#include <sys/asm_linkage.h>
30
31	ANSI_PRAGMA_WEAK(memset,function)
32
33#include "SYS.h"
34
35	ENTRY(memset)
36	pushl	%edi		/ save register variable
37	movl	8(%esp),%edi	/ %edi = string address
38	movl	12(%esp),%eax	/ %al = byte to duplicate
39	movl	16(%esp),%ecx	/ %ecx = number of copies
40	cmpl	$20,%ecx	/ strings with 20 or more chars should
41	jbe	.byteset	/ byteset one word at a time
42.wordset:
43	andl	$0xff,%eax	/ Duplicate fill const 4 times in %eax
44	shrl	$2,%ecx		/ %ecx = number of words to set
45	movl	%eax,%edx
46	shll	$8,%eax		/ This is ugly, but no P6 partial stalls
47	orl	%edx,%eax	/ get introduced as before
48	shll	$8,%eax
49	orl	%edx,%eax
50	shll	$8,%eax
51	orl	%edx,%eax
52	rep; sstol
53	movl	16(%esp),%ecx
54	andl	$3,%ecx		/ %ecx = number of bytes left
55.byteset:
56	rep; sstob
57	movl	8(%esp),%eax	/ return string address
58	popl	%edi		/ restore register variable
59	ret
60	SET_SIZE(memset)
61