1/* strcspn (str, ss) -- Return the length of the initial segment of STR
2 which contains only characters from SS.
3 For Intel 80x86, x>=3.
4 Copyright (C) 1994-2022 Free Software Foundation, Inc.
5 This file is part of the GNU C Library.
6
7 The GNU C Library is free software; you can redistribute it and/or
8 modify it under the terms of the GNU Lesser General Public
9 License as published by the Free Software Foundation; either
10 version 2.1 of the License, or (at your option) any later version.
11
12 The GNU C Library is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 Lesser General Public License for more details.
16
17 You should have received a copy of the GNU Lesser General Public
18 License along with the GNU C Library; if not, see
19 <https://www.gnu.org/licenses/>. */
20
21#include <sysdep.h>
22#include "asm-syntax.h"
23
24#define PARMS 4 /* no space for saved regs */
25#define STR PARMS
26#define SKIP STR+4
27
28 .text
29ENTRY (strspn)
30
31 movl STR(%esp), %edx
32 movl SKIP(%esp), %eax
33
34 /* First we create a table with flags for all possible characters.
35 For the ASCII (7bit/8bit) or ISO-8859-X character sets which are
36 supported by the C string functions we have 256 characters.
37 Before inserting marks for the stop characters we clear the whole
38 table. The unrolled form is much faster than a loop. */
39 xorl %ecx, %ecx /* %ecx = 0 !!! */
40
41 pushl %ecx /* make a 256 bytes long block filled with 0 */
42 cfi_adjust_cfa_offset (4)
43 pushl %ecx
44 cfi_adjust_cfa_offset (4)
45 pushl %ecx
46 cfi_adjust_cfa_offset (4)
47 pushl %ecx
48 cfi_adjust_cfa_offset (4)
49 pushl %ecx
50 cfi_adjust_cfa_offset (4)
51 pushl %ecx
52 cfi_adjust_cfa_offset (4)
53 pushl %ecx
54 cfi_adjust_cfa_offset (4)
55 pushl %ecx
56 cfi_adjust_cfa_offset (4)
57 pushl %ecx
58 cfi_adjust_cfa_offset (4)
59 pushl %ecx
60 cfi_adjust_cfa_offset (4)
61 pushl %ecx
62 cfi_adjust_cfa_offset (4)
63 pushl %ecx
64 cfi_adjust_cfa_offset (4)
65 pushl %ecx
66 cfi_adjust_cfa_offset (4)
67 pushl %ecx
68 cfi_adjust_cfa_offset (4)
69 pushl %ecx
70 cfi_adjust_cfa_offset (4)
71 pushl %ecx
72 cfi_adjust_cfa_offset (4)
73 pushl %ecx
74 cfi_adjust_cfa_offset (4)
75 pushl %ecx
76 cfi_adjust_cfa_offset (4)
77 pushl %ecx
78 cfi_adjust_cfa_offset (4)
79 pushl %ecx
80 cfi_adjust_cfa_offset (4)
81 pushl %ecx
82 cfi_adjust_cfa_offset (4)
83 pushl %ecx
84 cfi_adjust_cfa_offset (4)
85 pushl %ecx
86 cfi_adjust_cfa_offset (4)
87 pushl %ecx
88 cfi_adjust_cfa_offset (4)
89 pushl %ecx
90 cfi_adjust_cfa_offset (4)
91 pushl %ecx
92 cfi_adjust_cfa_offset (4)
93 pushl %ecx
94 cfi_adjust_cfa_offset (4)
95 pushl %ecx
96 cfi_adjust_cfa_offset (4)
97 pushl %ecx
98 cfi_adjust_cfa_offset (4)
99 pushl %ecx
100 cfi_adjust_cfa_offset (4)
101 pushl %ecx
102 cfi_adjust_cfa_offset (4)
103 pushl %ecx
104 cfi_adjust_cfa_offset (4)
105 pushl %ecx
106 cfi_adjust_cfa_offset (4)
107 pushl %ecx
108 cfi_adjust_cfa_offset (4)
109 pushl %ecx
110 cfi_adjust_cfa_offset (4)
111 pushl %ecx
112 cfi_adjust_cfa_offset (4)
113 pushl %ecx
114 cfi_adjust_cfa_offset (4)
115 pushl %ecx
116 cfi_adjust_cfa_offset (4)
117 pushl %ecx
118 cfi_adjust_cfa_offset (4)
119 pushl %ecx
120 cfi_adjust_cfa_offset (4)
121 pushl %ecx
122 cfi_adjust_cfa_offset (4)
123 pushl %ecx
124 cfi_adjust_cfa_offset (4)
125 pushl %ecx
126 cfi_adjust_cfa_offset (4)
127 pushl %ecx
128 cfi_adjust_cfa_offset (4)
129 pushl %ecx
130 cfi_adjust_cfa_offset (4)
131 pushl %ecx
132 cfi_adjust_cfa_offset (4)
133 pushl %ecx
134 cfi_adjust_cfa_offset (4)
135 pushl %ecx
136 cfi_adjust_cfa_offset (4)
137 pushl %ecx
138 cfi_adjust_cfa_offset (4)
139 pushl %ecx
140 cfi_adjust_cfa_offset (4)
141 pushl %ecx
142 cfi_adjust_cfa_offset (4)
143 pushl %ecx
144 cfi_adjust_cfa_offset (4)
145 pushl %ecx
146 cfi_adjust_cfa_offset (4)
147 pushl %ecx
148 cfi_adjust_cfa_offset (4)
149 pushl %ecx
150 cfi_adjust_cfa_offset (4)
151 pushl %ecx
152 cfi_adjust_cfa_offset (4)
153 pushl %ecx
154 cfi_adjust_cfa_offset (4)
155 pushl %ecx
156 cfi_adjust_cfa_offset (4)
157 pushl $0 /* These immediate values make the label 2 */
158 cfi_adjust_cfa_offset (4)
159 pushl $0 /* to be aligned on a 16 byte boundary to */
160 cfi_adjust_cfa_offset (4)
161 pushl $0 /* get a better performance of the loop. */
162 cfi_adjust_cfa_offset (4)
163 pushl $0
164 cfi_adjust_cfa_offset (4)
165 pushl $0
166 cfi_adjust_cfa_offset (4)
167 pushl $0
168 cfi_adjust_cfa_offset (4)
169
170/* For understanding the following code remember that %ecx == 0 now.
171 Although all the following instruction only modify %cl we always
172 have a correct zero-extended 32-bit value in %ecx. */
173
174/* Don't change the "testb $0xff,%%cl" to "testb %%cl,%%cl". We want
175 longer instructions so that the next loop aligns without adding nops. */
176
177L(2): movb (%eax), %cl /* get byte from stopset */
178 testb %cl, %cl /* is NUL char? */
179 jz L(1) /* yes => start compare loop */
180 movb %cl, (%esp,%ecx) /* set corresponding byte in stopset table */
181
182 movb 1(%eax), %cl /* get byte from stopset */
183 testb $0xff, %cl /* is NUL char? */
184 jz L(1) /* yes => start compare loop */
185 movb %cl, (%esp,%ecx) /* set corresponding byte in stopset table */
186
187 movb 2(%eax), %cl /* get byte from stopset */
188 testb $0xff, %cl /* is NUL char? */
189 jz L(1) /* yes => start compare loop */
190 movb %cl, (%esp,%ecx) /* set corresponding byte in stopset table */
191
192 movb 3(%eax), %cl /* get byte from stopset */
193 addl $4, %eax /* increment stopset pointer */
194 movb %cl, (%esp,%ecx) /* set corresponding byte in stopset table */
195 testb $0xff, %cl /* is NUL char? */
196 jnz L(2) /* no => process next dword from stopset */
197
198L(1): leal -4(%edx), %eax /* prepare loop */
199
200 /* We use a neat trick for the following loop. Normally we would
201 have to test for two termination conditions
202 1. a character in the stopset was found
203 and
204 2. the end of the string was found
205 But as a sign that the character is in the stopset we store its
206 value in the table. But the value of NUL is NUL so the loop
207 terminates for NUL in every case. */
208
209L(3): addl $4, %eax /* adjust pointer for full loop round */
210
211 movb (%eax), %cl /* get byte from string */
212 testb %cl, (%esp,%ecx) /* is it contained in skipset? */
213 jz L(4) /* no => return */
214
215 movb 1(%eax), %cl /* get byte from string */
216 testb %cl, (%esp,%ecx) /* is it contained in skipset? */
217 jz L(5) /* no => return */
218
219 movb 2(%eax), %cl /* get byte from string */
220 testb %cl, (%esp,%ecx) /* is it contained in skipset? */
221 jz L(6) /* no => return */
222
223 movb 3(%eax), %cl /* get byte from string */
224 testb %cl, (%esp,%ecx) /* is it contained in skipset? */
225 jnz L(3) /* yes => start loop again */
226
227 incl %eax /* adjust pointer */
228L(6): incl %eax
229L(5): incl %eax
230
231L(4): addl $256, %esp /* remove stopset */
232 cfi_adjust_cfa_offset (-256)
233 subl %edx, %eax /* we have to return the number of valid
234 characters, so compute distance to first
235 non-valid character */
236 ret
237END (strspn)
238libc_hidden_builtin_def (strspn)
239

source code of glibc/sysdeps/i386/strspn.S