FS#8961 - Anti-Aliased Fonts.
[kugel-rb.git] / firmware / common / strncmp.c
blob9801b7d924849d102cdc929527d1af2e25e4097b
1 /*
2 FUNCTION
3 <<strncmp>>---character string compare
5 INDEX
6 strncmp
8 ANSI_SYNOPSIS
9 #include <string.h>
10 int strncmp(const char *<[a]>, const char * <[b]>, size_t <[length]>);
12 TRAD_SYNOPSIS
13 #include <string.h>
14 int strncmp(<[a]>, <[b]>, <[length]>)
15 char *<[a]>;
16 char *<[b]>;
17 size_t <[length]>
19 DESCRIPTION
20 <<strncmp>> compares up to <[length]> characters
21 from the string at <[a]> to the string at <[b]>.
23 RETURNS
24 If <<*<[a]>>> sorts lexicographically after <<*<[b]>>>,
25 <<strncmp>> returns a number greater than zero. If the two
26 strings are equivalent, <<strncmp>> returns zero. If <<*<[a]>>>
27 sorts lexicographically before <<*<[b]>>>, <<strncmp>> returns a
28 number less than zero.
30 PORTABILITY
31 <<strncmp>> is ANSI C.
33 <<strncmp>> requires no supporting OS subroutines.
35 QUICKREF
36 strncmp ansi pure
39 #include <string.h>
40 #include <limits.h>
42 /* Nonzero if either X or Y is not aligned on a "long" boundary. */
43 #define UNALIGNED(X, Y) \
44 (((long)X & (sizeof (long) - 1)) | ((long)Y & (sizeof (long) - 1)))
46 /* DETECTNULL returns nonzero if (long)X contains a NULL byte. */
47 #if LONG_MAX == 2147483647L
48 #define DETECTNULL(X) (((X) - 0x01010101) & ~(X) & 0x80808080)
49 #else
50 #if LONG_MAX == 9223372036854775807L
51 #define DETECTNULL(X) (((X) - 0x0101010101010101) & ~(X) & 0x8080808080808080)
52 #else
53 #error long int is not a 32bit or 64bit type.
54 #endif
55 #endif
57 #ifndef DETECTNULL
58 #error long int is not a 32bit or 64bit byte
59 #endif
61 int
62 _DEFUN (strncmp, (s1, s2, n),
63 _CONST char *s1 _AND
64 _CONST char *s2 _AND
65 size_t n)
67 #if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__)
68 if (n == 0)
69 return 0;
71 while (n-- != 0 && *s1 == *s2)
73 if (n == 0 || *s1 == '\0')
74 break;
75 s1++;
76 s2++;
79 return (*(unsigned char *) s1) - (*(unsigned char *) s2);
80 #else
81 unsigned long *a1;
82 unsigned long *a2;
84 if (n == 0)
85 return 0;
87 /* If s1 or s2 are unaligned, then compare bytes. */
88 if (!UNALIGNED (s1, s2))
90 /* If s1 and s2 are word-aligned, compare them a word at a time. */
91 a1 = (unsigned long*)s1;
92 a2 = (unsigned long*)s2;
93 while (n >= sizeof (long) && *a1 == *a2)
95 n -= sizeof (long);
97 /* If we've run out of bytes or hit a null, return zero
98 since we already know *a1 == *a2. */
99 if (n == 0 || DETECTNULL (*a1))
100 return 0;
102 a1++;
103 a2++;
106 /* A difference was detected in last few bytes of s1, so search bytewise */
107 s1 = (char*)a1;
108 s2 = (char*)a2;
111 while (n-- > 0 && *s1 == *s2)
113 /* If we've run out of bytes or hit a null, return zero
114 since we already know *s1 == *s2. */
115 if (n == 0 || *s1 == '\0')
116 return 0;
117 s1++;
118 s2++;
120 return (*(unsigned char *) s1) - (*(unsigned char *) s2);
121 #endif /* not PREFER_SIZE_OVER_SPEED */