1 /*
2 FUNCTION
3 <<strcmp>>---character string compare
4
5 INDEX
6 strcmp
7
8 ANSI_SYNOPSIS
9 #include <string.h>
10 int strcmp(const char *<[a]>, const char *<[b]>);
11
12 TRAD_SYNOPSIS
13 #include <string.h>
14 int strcmp(<[a]>, <[b]>)
15 char *<[a]>;
16 char *<[b]>;
17
18 DESCRIPTION
19 <<strcmp>> compares the string at <[a]> to
20 the string at <[b]>.
21
22 RETURNS
23 If <<*<[a]>>> sorts lexicographically after <<*<[b]>>>,
24 <<strcmp>> returns a number greater than zero. If the two
25 strings match, <<strcmp>> returns zero. If <<*<[a]>>>
26 sorts lexicographically before <<*<[b]>>>, <<strcmp>> returns a
27 number less than zero.
28
29 PORTABILITY
30 <<strcmp>> is ANSI C.
31
32 <<strcmp>> requires no supporting OS subroutines.
33
34 QUICKREF
35 strcmp ansi pure
36 */
37
38 #include <section_config.h>
39 #include <basic_types.h>
40
41 #include <string.h>
42 #include <limits.h>
43
44 /* Nonzero if either X or Y is not aligned on a "long" boundary. */
45 #define UNALIGNED(X, Y) \
46 (((long)X & (sizeof (long) - 1)) | ((long)Y & (sizeof (long) - 1)))
47
48 /* DETECTNULL returns nonzero if (long)X contains a NULL byte. */
49 #if LONG_MAX == 2147483647L
50 #define DETECTNULL(X) (((X) - 0x01010101) & ~(X) & 0x80808080)
51 #else
52 #if LONG_MAX == 9223372036854775807L
53 #define DETECTNULL(X) (((X) - 0x0101010101010101) & ~(X) & 0x8080808080808080)
54 #else
55 #error long int is not a 32bit or 64bit type.
56 #endif
57 #endif
58
59 #ifndef DETECTNULL
60 #error long int is not a 32bit or 64bit byte
61 #endif
62
63 LIBC_ROM_TEXT_SECTION
64 _LONG_CALL_
_strcmp(const char * s1,const char * s2)65 int _strcmp(const char *s1 , const char *s2)
66 {
67 #if defined(PREFER_SIZE_OVER_SPEED)
68 while (*s1 != '\0' && *s1 == *s2)
69 {
70 s1++;
71 s2++;
72 }
73
74 return (*(unsigned char *) s1) - (*(unsigned char *) s2);
75 #else
76 unsigned long *a1;
77 unsigned long *a2;
78
79 /* If s1 or s2 are unaligned, then compare bytes. */
80 if (!UNALIGNED (s1, s2))
81 {
82 /* If s1 and s2 are word-aligned, compare them a word at a time. */
83 a1 = (unsigned long*)s1;
84 a2 = (unsigned long*)s2;
85 while (*a1 == *a2)
86 {
87 /* To get here, *a1 == *a2, thus if we find a null in *a1,
88 then the strings must be equal, so return zero. */
89 if (DETECTNULL (*a1))
90 return 0;
91
92 a1++;
93 a2++;
94 }
95
96 /* A difference was detected in last few bytes of s1, so search bytewise */
97 s1 = (char*)a1;
98 s2 = (char*)a2;
99 }
100
101 while (*s1 != '\0' && *s1 == *s2)
102 {
103 s1++;
104 s2++;
105 }
106 return (*(unsigned char *) s1) - (*(unsigned char *) s2);
107 #endif /* not PREFER_SIZE_OVER_SPEED */
108 }
109