streq.h revision 05436638acc7c010349a69c3395f1a57c642dc62 
1/* Optimized string comparison.
2   Copyright (C) 2001-2002, 2007, 2009-2012 Free Software Foundation, Inc.
3
4   This program is free software: you can redistribute it and/or modify it
5   under the terms of the GNU General Public License as published
6   by the Free Software Foundation; either version 3 of the License, or
7   (at your option) any later version.
8
9   This program is distributed in the hope that it will be useful,
10   but WITHOUT ANY WARRANTY; without even the implied warranty of
11   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
12   General Public License for more details.
13
14   You should have received a copy of the GNU General Public License
15   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
16
17/* Written by Bruno Haible <bruno@clisp.org>.  */
18
19#ifndef _GL_STREQ_H
20#define _GL_STREQ_H
21
22#include <string.h>
23
24/* STREQ_OPT allows to optimize string comparison with a small literal string.
25     STREQ_OPT (s, "EUC-KR", 'E', 'U', 'C', '-', 'K', 'R', 0, 0, 0)
26   is semantically equivalent to
27     strcmp (s, "EUC-KR") == 0
28   just faster.  */
29
30/* Help GCC to generate good code for string comparisons with
31   immediate strings. */
32#if defined (__GNUC__) && defined (__OPTIMIZE__)
33
34static inline int
35streq9 (const char *s1, const char *s2)
36{
37  return strcmp (s1 + 9, s2 + 9) == 0;
38}
39
40static inline int
41streq8 (const char *s1, const char *s2, char s28)
42{
43  if (s1[8] == s28)
44    {
45      if (s28 == 0)
46        return 1;
47      else
48        return streq9 (s1, s2);
49    }
50  else
51    return 0;
52}
53
54static inline int
55streq7 (const char *s1, const char *s2, char s27, char s28)
56{
57  if (s1[7] == s27)
58    {
59      if (s27 == 0)
60        return 1;
61      else
62        return streq8 (s1, s2, s28);
63    }
64  else
65    return 0;
66}
67
68static inline int
69streq6 (const char *s1, const char *s2, char s26, char s27, char s28)
70{
71  if (s1[6] == s26)
72    {
73      if (s26 == 0)
74        return 1;
75      else
76        return streq7 (s1, s2, s27, s28);
77    }
78  else
79    return 0;
80}
81
82static inline int
83streq5 (const char *s1, const char *s2, char s25, char s26, char s27, char s28)
84{
85  if (s1[5] == s25)
86    {
87      if (s25 == 0)
88        return 1;
89      else
90        return streq6 (s1, s2, s26, s27, s28);
91    }
92  else
93    return 0;
94}
95
96static inline int
97streq4 (const char *s1, const char *s2, char s24, char s25, char s26, char s27, char s28)
98{
99  if (s1[4] == s24)
100    {
101      if (s24 == 0)
102        return 1;
103      else
104        return streq5 (s1, s2, s25, s26, s27, s28);
105    }
106  else
107    return 0;
108}
109
110static inline int
111streq3 (const char *s1, const char *s2, char s23, char s24, char s25, char s26, char s27, char s28)
112{
113  if (s1[3] == s23)
114    {
115      if (s23 == 0)
116        return 1;
117      else
118        return streq4 (s1, s2, s24, s25, s26, s27, s28);
119    }
120  else
121    return 0;
122}
123
124static inline int
125streq2 (const char *s1, const char *s2, char s22, char s23, char s24, char s25, char s26, char s27, char s28)
126{
127  if (s1[2] == s22)
128    {
129      if (s22 == 0)
130        return 1;
131      else
132        return streq3 (s1, s2, s23, s24, s25, s26, s27, s28);
133    }
134  else
135    return 0;
136}
137
138static inline int
139streq1 (const char *s1, const char *s2, char s21, char s22, char s23, char s24, char s25, char s26, char s27, char s28)
140{
141  if (s1[1] == s21)
142    {
143      if (s21 == 0)
144        return 1;
145      else
146        return streq2 (s1, s2, s22, s23, s24, s25, s26, s27, s28);
147    }
148  else
149    return 0;
150}
151
152static inline int
153streq0 (const char *s1, const char *s2, char s20, char s21, char s22, char s23, char s24, char s25, char s26, char s27, char s28)
154{
155  if (s1[0] == s20)
156    {
157      if (s20 == 0)
158        return 1;
159      else
160        return streq1 (s1, s2, s21, s22, s23, s24, s25, s26, s27, s28);
161    }
162  else
163    return 0;
164}
165
166#define STREQ_OPT(s1,s2,s20,s21,s22,s23,s24,s25,s26,s27,s28) \
167  streq0 (s1, s2, s20, s21, s22, s23, s24, s25, s26, s27, s28)
168
169#else
170
171#define STREQ_OPT(s1,s2,s20,s21,s22,s23,s24,s25,s26,s27,s28) \
172  (strcmp (s1, s2) == 0)
173
174#endif
175
176#endif /* _GL_STREQ_H */
177