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comparison src/strcmp.c @ 0:376386a54a3c r19-14

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Import from CVS: tag r19-14
author cvs
date Mon, 13 Aug 2007 08:45:50 +0200
parents
children 850242ba4a81
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-1:000000000000 0:376386a54a3c
1 /* This file is part of XEmacs.
2
3 XEmacs is free software; you can redistribute it and/or modify it
4 under the terms of the GNU General Public License as published by the
5 Free Software Foundation; either version 2, or (at your option) any
6 later version.
7
8 XEmacs is distributed in the hope that it will be useful, but WITHOUT
9 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
11 for more details.
12
13 You should have received a copy of the GNU General Public License
14 along with XEmacs; see the file COPYING. If not, write to
15 the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
16 Boston, MA 02111-1307, USA. */
17
18 /* Synched up with: Not in FSF. */
19
20 /* In SunOS 4.1.1 the strcmp and strncmp functions reference memory
21 past the last byte of the string! This will core dump if the memory
22 following the last byte is not mapped.
23
24 Here are correct versions by hbs@lucid.com.
25 */
26
27 #include <string.h>
28 #define ALIGNED(x) (!(((unsigned long) (x)) & (sizeof (unsigned long) - 1)))
29
30 #define MAGIC 0x7efefeff
31 #define HIGH_BIT_P(c) ((c) & hi_bit)
32 #define HAS_ZERO(c) (((((c) + magic) ^ (c)) & not_magic) != not_magic)
33
34 int
35 strcmp (const char *x, const char *y)
36 {
37 if (x == y)
38 return 0;
39 else if (ALIGNED (x) && ALIGNED (y))
40 {
41 const unsigned long *x1 = (const unsigned long *) x;
42 const unsigned long *y1 = (const unsigned long *) y;
43 unsigned long c;
44 unsigned long magic = MAGIC;
45 unsigned long not_magic = ~magic;
46 unsigned long hi_bit = 0x80000000;
47
48 while ((c = *x1) == *y1)
49 {
50 if (HAS_ZERO(c))
51 {
52 if (!HIGH_BIT_P (c))
53 return 0;
54 else
55 {
56 x = (const char *) x1;
57 y = (const char *) y1;
58 goto slow_loop;
59 }
60 }
61
62 x1++;
63 y1++;
64 }
65
66 x = (const char *) x1;
67 y = (const char *) y1;
68 goto slow_loop;
69 }
70 else
71 {
72 char c;
73
74 slow_loop:
75
76 while ((c = *x) == *y)
77 {
78 if (c == (char) 0) return 0;
79 x++;
80 y++;
81 }
82 return (*x - *y);
83 }
84 }
85
86
87 int
88 strncmp (const char *x, const char *y, size_t n)
89 {
90 if ((x == y) || (n <= 0))
91 return 0;
92 else if (ALIGNED (x) && ALIGNED (y))
93 {
94 const unsigned long *x1 = (const unsigned long *) x;
95 const unsigned long *y1 = (const unsigned long *) y;
96 unsigned long c;
97 unsigned long magic = MAGIC;
98 unsigned long not_magic = ~magic;
99 unsigned long hi_bit = 0x80000000;
100
101 while ((c = *x1) == *y1)
102 {
103 n -= sizeof (unsigned long);
104 if (n <= 0)
105 return 0;
106
107 if (HAS_ZERO(c))
108 {
109 if (!HIGH_BIT_P (c))
110 return 0;
111 else
112 {
113 x = (const char *) x1;
114 y = (const char *) y1;
115 goto slow_loop;
116 }
117 }
118
119 x1++;
120 y1++;
121 }
122
123 x = (const char *) x1;
124 y = (const char *) y1;
125 goto slow_loop;
126 }
127 else
128 {
129 char c;
130
131 slow_loop:
132
133 while ((c = *x) == *y)
134 {
135 n--;
136 if (n <= 0)
137 return 0;
138 if (c == (char) 0)
139 return 0;
140 x++;
141 y++;
142 }
143 return (*x - *y);
144 }
145 }