xref: /openbsd-src/lib/libc/arch/i386/string/strcpy.S (revision 8500990981f885cbe5e6a4958549cacc238b5ae6)
1/*
2 * Written by J.T. Conklin <jtc@netbsd.org>.
3 * Public domain.
4 */
5
6#include <machine/asm.h>
7
8#if defined(APIWARN)
9#APP
10	.stabs "warning: strcpy() is almost always misused, consider using strlcpy()",30,0,0,0
11	.stabs "_strcpy",1,0,0,0
12#NO_APP
13#endif
14
15#if defined(LIBC_SCCS)
16	.text
17	.asciz "$OpenBSD: strcpy.S,v 1.5 2003/07/24 01:15:42 deraadt Exp $"
18#endif
19
20/*
21 * NOTE: I've unrolled the loop eight times: large enough to make a
22 * significant difference, and small enough not to totally trash the
23 * cache.
24 */
25
26ENTRY(strcpy)
27	movl	4(%esp),%ecx		/* dst address */
28	movl	8(%esp),%edx		/* src address */
29	pushl	%ecx			/* push dst address */
30
31	.align 2,0x90
32L1:	movb	(%edx),%al		/* unroll loop, but not too much */
33	movb	%al,(%ecx)
34	testb	%al,%al
35	jz	L2
36	movb	1(%edx),%al
37	movb	%al,1(%ecx)
38	testb	%al,%al
39	jz	L2
40	movb	2(%edx),%al
41	movb	%al,2(%ecx)
42	testb	%al,%al
43	jz	L2
44	movb	3(%edx),%al
45	movb	%al,3(%ecx)
46	testb	%al,%al
47	jz	L2
48	movb	4(%edx),%al
49	movb	%al,4(%ecx)
50	testb	%al,%al
51	jz	L2
52	movb	5(%edx),%al
53	movb	%al,5(%ecx)
54	testb	%al,%al
55	jz	L2
56	movb	6(%edx),%al
57	movb	%al,6(%ecx)
58	testb	%al,%al
59	jz	L2
60	movb	7(%edx),%al
61	movb	%al,7(%ecx)
62	addl	$8,%edx
63	addl	$8,%ecx
64	testb	%al,%al
65	jnz	L1
66L2:	popl	%eax			/* pop dst address */
67	ret
68