diff options
Diffstat (limited to 'firmware/libc/strncmp.c')
-rw-r--r-- | firmware/libc/strncmp.c | 122 |
1 files changed, 122 insertions, 0 deletions
diff --git a/firmware/libc/strncmp.c b/firmware/libc/strncmp.c new file mode 100644 index 0000000000..b1d8d9d43a --- /dev/null +++ b/firmware/libc/strncmp.c | |||
@@ -0,0 +1,122 @@ | |||
1 | /* | ||
2 | FUNCTION | ||
3 | <<strncmp>>---character string compare | ||
4 | |||
5 | INDEX | ||
6 | strncmp | ||
7 | |||
8 | ANSI_SYNOPSIS | ||
9 | #include <string.h> | ||
10 | int strncmp(const char *<[a]>, const char * <[b]>, size_t <[length]>); | ||
11 | |||
12 | TRAD_SYNOPSIS | ||
13 | #include <string.h> | ||
14 | int strncmp(<[a]>, <[b]>, <[length]>) | ||
15 | char *<[a]>; | ||
16 | char *<[b]>; | ||
17 | size_t <[length]> | ||
18 | |||
19 | DESCRIPTION | ||
20 | <<strncmp>> compares up to <[length]> characters | ||
21 | from the string at <[a]> to the string at <[b]>. | ||
22 | |||
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. | ||
29 | |||
30 | PORTABILITY | ||
31 | <<strncmp>> is ANSI C. | ||
32 | |||
33 | <<strncmp>> requires no supporting OS subroutines. | ||
34 | |||
35 | QUICKREF | ||
36 | strncmp ansi pure | ||
37 | */ | ||
38 | |||
39 | #include <string.h> | ||
40 | #include <limits.h> | ||
41 | |||
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))) | ||
45 | |||
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 | ||
56 | |||
57 | #ifndef DETECTNULL | ||
58 | #error long int is not a 32bit or 64bit byte | ||
59 | #endif | ||
60 | |||
61 | int | ||
62 | _DEFUN (strncmp, (s1, s2, n), | ||
63 | _CONST char *s1 _AND | ||
64 | _CONST char *s2 _AND | ||
65 | size_t n) | ||
66 | { | ||
67 | #if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__) | ||
68 | if (n == 0) | ||
69 | return 0; | ||
70 | |||
71 | while (n-- != 0 && *s1 == *s2) | ||
72 | { | ||
73 | if (n == 0 || *s1 == '\0') | ||
74 | break; | ||
75 | s1++; | ||
76 | s2++; | ||
77 | } | ||
78 | |||
79 | return (*(unsigned char *) s1) - (*(unsigned char *) s2); | ||
80 | #else | ||
81 | unsigned long *a1; | ||
82 | unsigned long *a2; | ||
83 | |||
84 | if (n == 0) | ||
85 | return 0; | ||
86 | |||
87 | /* If s1 or s2 are unaligned, then compare bytes. */ | ||
88 | if (!UNALIGNED (s1, s2)) | ||
89 | { | ||
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) | ||
94 | { | ||
95 | n -= sizeof (long); | ||
96 | |||
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; | ||
101 | |||
102 | a1++; | ||
103 | a2++; | ||
104 | } | ||
105 | |||
106 | /* A difference was detected in last few bytes of s1, so search bytewise */ | ||
107 | s1 = (char*)a1; | ||
108 | s2 = (char*)a2; | ||
109 | } | ||
110 | |||
111 | while (n-- > 0 && *s1 == *s2) | ||
112 | { | ||
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++; | ||
119 | } | ||
120 | return (*(unsigned char *) s1) - (*(unsigned char *) s2); | ||
121 | #endif /* not PREFER_SIZE_OVER_SPEED */ | ||
122 | } | ||