aboutsummaryrefslogtreecommitdiff
path: root/sysdeps/i386/i586/strcpy.S
blob: b06149153249fd9b4b14801a794a0eec9246d52e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
/* strcpy/stpcpy implementation for i586.
   Copyright (C) 1997-2014 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 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
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <http://www.gnu.org/licenses/>.  */

#include <sysdep.h>
#include "asm-syntax.h"

#define PARMS	4+12	/* space for 3 saved regs */
#define RTN	PARMS
#define DEST	RTN
#define SRC	DEST+4

#ifndef USE_AS_STPCPY
# define STRCPY strcpy
#endif

#define magic 0xfefefeff

	.text
ENTRY (STRCPY)

	pushl	%edi
	cfi_adjust_cfa_offset (4)
	pushl	%esi
	cfi_adjust_cfa_offset (4)
	pushl	%ebx
	cfi_adjust_cfa_offset (4)

	movl	DEST(%esp), %edi
	cfi_rel_offset (edi, 8)
	movl	SRC(%esp), %esi
	cfi_rel_offset (esi, 4)

	xorl	%eax, %eax
	leal	-1(%esi), %ecx

	movl	$magic, %ebx
	cfi_rel_offset (ebx, 0)
	andl	$3, %ecx

#ifdef PIC
	call	2f
	cfi_adjust_cfa_offset (4)
2:	popl	%edx
	cfi_adjust_cfa_offset (-4)
	/* 0xb is the distance between 2: and 1: but we avoid writing
	   1f-2b because the assembler generates worse code.  */
	leal	0xb(%edx,%ecx,8), %ecx
#else
	leal	1f(,%ecx,8), %ecx
#endif

	jmp	*%ecx

	.align 8
1:
	orb	(%esi), %al
	jz	L(end)
	stosb
	xorl	%eax, %eax
	incl	%esi

	orb	(%esi), %al
	jz	L(end)
	stosb
	xorl	%eax, %eax
	incl	%esi

	orb	(%esi), %al
	jz	L(end)
	stosb
	xorl	%eax, %eax
	incl	%esi

L(1):	movl	(%esi), %ecx
	leal	4(%esi),%esi

	subl	%ecx, %eax
	addl	%ebx, %ecx

	decl	%eax
	jnc	L(3)

	movl	%ecx, %edx
	xorl	%ecx, %eax

	subl	%ebx, %edx
	andl	$~magic, %eax

	jne	L(4)

	movl	%edx, (%edi)
	leal	4(%edi),%edi

	jmp	L(1)

L(3):	movl	%ecx, %edx

	subl	%ebx, %edx

L(4):	movb	%dl, (%edi)
	testb	%dl, %dl

	movl	%edx, %eax
	jz	L(end2)

	shrl	$16, %eax
	movb	%dh, 1(%edi)
#ifdef USE_AS_STPCPY
	addl	$1, %edi
#endif

	cmpb	$0, %dh
	jz	L(end2)

#ifdef USE_AS_STPCPY
	movb	%al, 1(%edi)
	addl	$1, %edi

	cmpb	$0, %al
	jz	L(end2)

	addl	$1, %edi
#else
	movb	%al, 2(%edi)
	testb	%al, %al

	leal	3(%edi), %edi
	jz	L(end2)
#endif

L(end):	movb	%ah, (%edi)

L(end2):
#ifdef USE_AS_STPCPY
	movl	%edi, %eax
#else
	movl	DEST(%esp), %eax
#endif
	popl	%ebx
	cfi_adjust_cfa_offset (-4)
	cfi_restore (ebx)
	popl	%esi
	cfi_adjust_cfa_offset (-4)
	cfi_restore (esi)
	popl	%edi
	cfi_adjust_cfa_offset (-4)
	cfi_restore (edi)

	ret
END (STRCPY)
#ifndef USE_AS_STPCPY
libc_hidden_builtin_def (strcpy)
#endif