1/*	$OpenBSD: memset.S,v 1.4 2014/11/29 18:51:23 tedu Exp $	*/
2
3/*
4 * Written by J.T. Conklin <jtc@netbsd.org>.
5 * Public domain.
6 */
7
8#include <machine/asm.h>
9
10ENTRY(memset)
11	pushl	%edi
12	pushl	%ebx
13	movl	12(%esp),%edi
14	movzbl	16(%esp),%eax		/* unsigned char, zero extend */
15	movl	20(%esp),%ecx
16	pushl	%edi			/* push address of buffer */
17
18	/*
19	 * if the string is too short, it's really not worth the overhead
20	 * of aligning to word boundaries, etc.  So we jump to a plain
21	 * unaligned set.
22	 */
23	cmpl	$0x0f,%ecx
24	jle	L1
25
26	movb	%al,%ah			/* copy char to all bytes in word */
27	movl	%eax,%edx
28	sall	$16,%eax
29	orl	%edx,%eax
30
31	movl	%edi,%edx		/* compute misalignment */
32	negl	%edx
33	andl	$3,%edx
34	movl	%ecx,%ebx
35	subl	%edx,%ebx
36
37	movl	%edx,%ecx		/* set until word aligned */
38	rep
39	stosb
40
41	movl	%ebx,%ecx
42	shrl	$2,%ecx			/* set by words */
43	rep
44	stosl
45
46	movl	%ebx,%ecx		/* set remainder by bytes */
47	andl	$3,%ecx
48L1:	rep
49	stosb
50
51	popl	%eax			/* pop address of buffer */
52	popl	%ebx
53	popl	%edi
54	ret
55