diff options
Diffstat (limited to 'firmware/asm/strlen.c')
-rw-r--r-- | firmware/asm/strlen.c | 93 |
1 files changed, 93 insertions, 0 deletions
diff --git a/firmware/asm/strlen.c b/firmware/asm/strlen.c new file mode 100644 index 0000000000..649df6764b --- /dev/null +++ b/firmware/asm/strlen.c | |||
@@ -0,0 +1,93 @@ | |||
1 | /* | ||
2 | FUNCTION | ||
3 | <<strlen>>---character string length | ||
4 | |||
5 | INDEX | ||
6 | strlen | ||
7 | |||
8 | ANSI_SYNOPSIS | ||
9 | #include <string.h> | ||
10 | size_t strlen(const char *<[str]>); | ||
11 | |||
12 | TRAD_SYNOPSIS | ||
13 | #include <string.h> | ||
14 | size_t strlen(<[str]>) | ||
15 | char *<[src]>; | ||
16 | |||
17 | DESCRIPTION | ||
18 | The <<strlen>> function works out the length of the string | ||
19 | starting at <<*<[str]>>> by counting chararacters until it | ||
20 | reaches a <<NULL>> character. | ||
21 | |||
22 | RETURNS | ||
23 | <<strlen>> returns the character count. | ||
24 | |||
25 | PORTABILITY | ||
26 | <<strlen>> is ANSI C. | ||
27 | |||
28 | <<strlen>> requires no supporting OS subroutines. | ||
29 | |||
30 | QUICKREF | ||
31 | strlen ansi pure | ||
32 | */ | ||
33 | |||
34 | #include "config.h" | ||
35 | #include "_ansi.h" | ||
36 | #include <string.h> | ||
37 | #include <limits.h> | ||
38 | |||
39 | #define LBLOCKSIZE (sizeof (long)) | ||
40 | #define UNALIGNED(X) ((long)X & (LBLOCKSIZE - 1)) | ||
41 | |||
42 | #if LONG_MAX == 2147483647L | ||
43 | #define DETECTNULL(X) (((X) - 0x01010101) & ~(X) & 0x80808080) | ||
44 | #else | ||
45 | #if LONG_MAX == 9223372036854775807L | ||
46 | /* Nonzero if X (a long int) contains a NULL byte. */ | ||
47 | #define DETECTNULL(X) (((X) - 0x0101010101010101) & ~(X) & 0x8080808080808080) | ||
48 | #else | ||
49 | #error long int is not a 32bit or 64bit type. | ||
50 | #endif | ||
51 | #endif | ||
52 | |||
53 | #ifndef DETECTNULL | ||
54 | #error long int is not a 32bit or 64bit byte | ||
55 | #endif | ||
56 | |||
57 | size_t | ||
58 | _DEFUN (strlen, (str), | ||
59 | _CONST char *str) ICODE_ATTR; | ||
60 | |||
61 | size_t | ||
62 | _DEFUN (strlen, (str), | ||
63 | _CONST char *str) | ||
64 | { | ||
65 | #if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__) | ||
66 | _CONST char *start = str; | ||
67 | |||
68 | while (*str) | ||
69 | str++; | ||
70 | |||
71 | return str - start; | ||
72 | #else | ||
73 | _CONST char *start = str; | ||
74 | unsigned long *aligned_addr; | ||
75 | |||
76 | if (!UNALIGNED (str)) | ||
77 | { | ||
78 | /* If the string is word-aligned, we can check for the presence of | ||
79 | a null in each word-sized block. */ | ||
80 | aligned_addr = (unsigned long*)str; | ||
81 | while (!DETECTNULL (*aligned_addr)) | ||
82 | aligned_addr++; | ||
83 | |||
84 | /* Once a null is detected, we check each byte in that block for a | ||
85 | precise position of the null. */ | ||
86 | str = (char*)aligned_addr; | ||
87 | } | ||
88 | |||
89 | while (*str) | ||
90 | str++; | ||
91 | return str - start; | ||
92 | #endif /* not PREFER_SIZE_OVER_SPEED */ | ||
93 | } | ||