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 
34 static inline int
streq9(const char * s1,const char * s2)35 streq9 (const char *s1, const char *s2)
36 {
37   return strcmp (s1 + 9, s2 + 9) == 0;
38 }
39 
40 static inline int
streq8(const char * s1,const char * s2,char s28)41 streq8 (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 
54 static inline int
streq7(const char * s1,const char * s2,char s27,char s28)55 streq7 (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 
68 static inline int
streq6(const char * s1,const char * s2,char s26,char s27,char s28)69 streq6 (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 
82 static inline int
streq5(const char * s1,const char * s2,char s25,char s26,char s27,char s28)83 streq5 (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 
96 static inline int
streq4(const char * s1,const char * s2,char s24,char s25,char s26,char s27,char s28)97 streq4 (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 
110 static inline int
streq3(const char * s1,const char * s2,char s23,char s24,char s25,char s26,char s27,char s28)111 streq3 (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 
124 static inline int
streq2(const char * s1,const char * s2,char s22,char s23,char s24,char s25,char s26,char s27,char s28)125 streq2 (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 
138 static inline int
streq1(const char * s1,const char * s2,char s21,char s22,char s23,char s24,char s25,char s26,char s27,char s28)139 streq1 (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 
152 static inline int
streq0(const char * s1,const char * s2,char s20,char s21,char s22,char s23,char s24,char s25,char s26,char s27,char s28)153 streq0 (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