1/* ----------------------------------------------------------------------- *
2 *
3 *   Copyright 2008 H. Peter Anvin - All Rights Reserved
4 *
5 *   Permission is hereby granted, free of charge, to any person
6 *   obtaining a copy of this software and associated documentation
7 *   files (the "Software"), to deal in the Software without
8 *   restriction, including without limitation the rights to use,
9 *   copy, modify, merge, publish, distribute, sublicense, and/or
10 *   sell copies of the Software, and to permit persons to whom
11 *   the Software is furnished to do so, subject to the following
12 *   conditions:
13 *
14 *   The above copyright notice and this permission notice shall
15 *   be included in all copies or substantial portions of the Software.
16 *
17 *   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
18 *   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
19 *   OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
20 *   NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
21 *   HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
22 *   WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
23 *   FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
24 *   OTHER DEALINGS IN THE SOFTWARE.
25 *
26 * ----------------------------------------------------------------------- */
27
28/*
29 * memset.S
30 *
31 * Reasonably efficient memset, using aligned transfers at least
32 * for the destination operand.
33 */
34
35	.globl	memset
36	.type	memset,@function
37	.text
38memset:
39	jecxz	6f
40
41	pushl	%edi
42	pushl	%ebx
43	pushl	%eax		/* Return value */
44
45	movl	%eax,%edi
46	movb	%dl,%dh
47	movzwl	%dx,%eax
48	shll	$16,%edx
49	orl	%edx,%eax
50
51	/* Initial alignment */
52	movl	%edi,%edx
53	shrl	$1,%edx
54	jnc	1f
55	stosb
56	decl	%ecx
571:
58	movb	%cl,%bl
59	cmpl	$2,%ecx
60	jb	3f
61	shrl	$1,%edx
62	jnc	2f
63	stosw
64	subl	$2,%ecx
652:
66	/* Bulk transfer */
67	movb	%cl,%bl
68	shrl	$2,%ecx
69	rep; stosl
70
71	testb	$2,%bl
72	jz	4f
73	stosw
743:
754:
76	testb	$1,%bl
77	jz	5f
78	stosb
795:
80	popl	%eax		/* Return value */
81	popl	%ebx
82	popl	%edi
836:
84	ret
85
86	.size	memset, .-memset
87