tsiry-sandratraina.com
A modern Music Player Daemon based on Rockbox open source high quality audio player
libadwaita
audio
rust
zig
deno
mpris
rockbox
mpd
1/*
2FUNCTION
3 <<strchr>>---search for character in string
4
5INDEX
6 strchr
7
8ANSI_SYNOPSIS
9 #include <string.h>
10 char * strchr(const char *<[string]>, int <[c]>);
11
12TRAD_SYNOPSIS
13 #include <string.h>
14 char * strchr(<[string]>, <[c]>);
15 char *<[string]>;
16 int *<[c]>;
17
18DESCRIPTION
19 This function finds the first occurence of <[c]> (converted to
20 a char) in the string pointed to by <[string]> (including the
21 terminating null character).
22
23RETURNS
24 Returns a pointer to the located character, or a null pointer
25 if <[c]> does not occur in <[string]>.
26
27PORTABILITY
28<<strchr>> is ANSI C.
29
30<<strchr>> requires no supporting OS subroutines.
31
32QUICKREF
33 strchr ansi pure
34*/
35
36#include <string.h>
37#include <limits.h>
38#include "_ansi.h" /* for _DEFUN */
39
40/* Nonzero if X is not aligned on a "long" boundary. */
41#define ROCKBOX_UNALIGNED(X) ((long)X & (sizeof (long) - 1))
42
43/* How many bytes are loaded each iteration of the word copy loop. */
44#define LBLOCKSIZE (sizeof (long))
45
46#if LONG_MAX == 2147483647L
47#define DETECTNULL(X) (((X) - 0x01010101) & ~(X) & 0x80808080)
48#else
49#if LONG_MAX == 9223372036854775807L
50/* Nonzero if X (a long int) contains a NULL byte. */
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/* DETECTCHAR returns nonzero if (long)X contains the byte used
58 to fill (long)MASK. */
59#define DETECTCHAR(X,MASK) (DETECTNULL(X ^ MASK))
60
61char *
62_DEFUN (strchr, (s1, i),
63 _CONST char *s1 _AND
64 int i)
65{
66 _CONST unsigned char *s = (_CONST unsigned char *)s1;
67#if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__)
68 unsigned char c = (unsigned int)i;
69
70 while (*s && *s != c)
71 {
72 s++;
73 }
74
75 if (*s != c)
76 {
77 s = NULL;
78 }
79
80 return (char *) s;
81#else
82 unsigned char c = (unsigned char)i;
83 unsigned long mask,j;
84 unsigned long *aligned_addr;
85
86 if (!ROCKBOX_UNALIGNED (s))
87 {
88 mask = 0;
89 for (j = 0; j < LBLOCKSIZE; j++)
90 mask = (mask << 8) | c;
91
92 aligned_addr = (unsigned long*)s;
93 while (!DETECTNULL (*aligned_addr) && !DETECTCHAR (*aligned_addr, mask))
94 aligned_addr++;
95
96 /* The block of bytes currently pointed to by aligned_addr
97 contains either a null or the target char, or both. We
98 catch it using the bytewise search. */
99
100 s = (unsigned char*)aligned_addr;
101 }
102
103 while (*s && *s != c)
104 s++;
105 if (*s == c)
106 return (char *)s;
107 return NULL;
108#endif /* not PREFER_SIZE_OVER_SPEED */
109}