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
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
|
/* strcspn (str, ss) -- Return the length of the initial segment of STR
which contains only characters from SS.
For Intel 80x86, x>=3.
Copyright (C) 1994-2020 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@gnu.ai.mit.edu>
Bug fixes by Alan Modra <Alan@SPRI.Levels.UniSA.Edu.Au>
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
<https://www.gnu.org/licenses/>. */
#include <sysdep.h>
#include "asm-syntax.h"
#define PARMS 4 /* no space for saved regs */
#define STR PARMS
#define SKIP STR+4
.text
ENTRY (strspn)
movl STR(%esp), %edx
movl SKIP(%esp), %eax
/* First we create a table with flags for all possible characters.
For the ASCII (7bit/8bit) or ISO-8859-X character sets which are
supported by the C string functions we have 256 characters.
Before inserting marks for the stop characters we clear the whole
table. The unrolled form is much faster than a loop. */
xorl %ecx, %ecx /* %ecx = 0 !!! */
pushl %ecx /* make a 256 bytes long block filled with 0 */
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl $0 /* These immediate values make the label 2 */
cfi_adjust_cfa_offset (4)
pushl $0 /* to be aligned on a 16 byte boundary to */
cfi_adjust_cfa_offset (4)
pushl $0 /* get a better performance of the loop. */
cfi_adjust_cfa_offset (4)
pushl $0
cfi_adjust_cfa_offset (4)
pushl $0
cfi_adjust_cfa_offset (4)
pushl $0
cfi_adjust_cfa_offset (4)
/* For understanding the following code remember that %ecx == 0 now.
Although all the following instruction only modify %cl we always
have a correct zero-extended 32-bit value in %ecx. */
/* Don't change the "testb $0xff,%%cl" to "testb %%cl,%%cl". We want
longer instructions so that the next loop aligns without adding nops. */
L(2): movb (%eax), %cl /* get byte from stopset */
testb %cl, %cl /* is NUL char? */
jz L(1) /* yes => start compare loop */
movb %cl, (%esp,%ecx) /* set corresponding byte in stopset table */
movb 1(%eax), %cl /* get byte from stopset */
testb $0xff, %cl /* is NUL char? */
jz L(1) /* yes => start compare loop */
movb %cl, (%esp,%ecx) /* set corresponding byte in stopset table */
movb 2(%eax), %cl /* get byte from stopset */
testb $0xff, %cl /* is NUL char? */
jz L(1) /* yes => start compare loop */
movb %cl, (%esp,%ecx) /* set corresponding byte in stopset table */
movb 3(%eax), %cl /* get byte from stopset */
addl $4, %eax /* increment stopset pointer */
movb %cl, (%esp,%ecx) /* set corresponding byte in stopset table */
testb $0xff, %cl /* is NUL char? */
jnz L(2) /* no => process next dword from stopset */
L(1): leal -4(%edx), %eax /* prepare loop */
/* We use a neat trick for the following loop. Normally we would
have to test for two termination conditions
1. a character in the stopset was found
and
2. the end of the string was found
But as a sign that the character is in the stopset we store its
value in the table. But the value of NUL is NUL so the loop
terminates for NUL in every case. */
L(3): addl $4, %eax /* adjust pointer for full loop round */
movb (%eax), %cl /* get byte from string */
testb %cl, (%esp,%ecx) /* is it contained in skipset? */
jz L(4) /* no => return */
movb 1(%eax), %cl /* get byte from string */
testb %cl, (%esp,%ecx) /* is it contained in skipset? */
jz L(5) /* no => return */
movb 2(%eax), %cl /* get byte from string */
testb %cl, (%esp,%ecx) /* is it contained in skipset? */
jz L(6) /* no => return */
movb 3(%eax), %cl /* get byte from string */
testb %cl, (%esp,%ecx) /* is it contained in skipset? */
jnz L(3) /* yes => start loop again */
incl %eax /* adjust pointer */
L(6): incl %eax
L(5): incl %eax
L(4): addl $256, %esp /* remove stopset */
cfi_adjust_cfa_offset (-256)
subl %edx, %eax /* we have to return the number of valid
characters, so compute distance to first
non-valid character */
ret
END (strspn)
libc_hidden_builtin_def (strspn)
|
GitWeb