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 <<memccpy>>---copy memory regions with end-token check
4ANSI_SYNOPSIS
5 #include <string.h>
6 void* memccpy(void *restrict <[out]>, const void *restrict <[in]>,
7 int <[endchar]>, size_t <[n]>);
8TRAD_SYNOPSIS
9 void *memccpy(<[out]>, <[in]>, <[endchar]>, <[n]>
10 void *<[out]>;
11 void *<[in]>;
12 int <[endchar]>;
13 size_t <[n]>;
14DESCRIPTION
15 This function copies up to <[n]> bytes from the memory region
16 pointed to by <[in]> to the memory region pointed to by
17 <[out]>. If a byte matching the <[endchar]> is encountered,
18 the byte is copied and copying stops.
19 If the regions overlap, the behavior is undefined.
20RETURNS
21 <<memccpy>> returns a pointer to the first byte following the
22 <[endchar]> in the <[out]> region. If no byte matching
23 <[endchar]> was copied, then <<NULL>> is returned.
24PORTABILITY
25<<memccpy>> is a GNU extension.
26<<memccpy>> requires no supporting OS subroutines.
27 */
28#include <stddef.h>
29#include <string.h>
30#include <limits.h>
31#include "_ansi.h" /* for _DEFUN */
32
33/* Nonzero if either X or Y is not aligned on a "long" boundary. */
34#define ROCKBOX_UNALIGNED(X, Y) \
35 (((long)X & (sizeof (long) - 1)) | ((long)Y & (sizeof (long) - 1)))
36/* How many bytes are copied each iteration of the word copy loop. */
37#define LITTLEBLOCKSIZE (sizeof (long))
38/* Threshhold for punting to the byte copier. */
39#define TOO_SMALL(LEN) ((LEN) < LITTLEBLOCKSIZE)
40/* Macros for detecting endchar */
41#if LONG_MAX == 2147483647L
42#define DETECTNULL(X) (((X) - 0x01010101) & ~(X) & 0x80808080)
43#else
44#if LONG_MAX == 9223372036854775807L
45/* Nonzero if X (a long int) contains a NULL byte. */
46#define DETECTNULL(X) (((X) - 0x0101010101010101) & ~(X) & 0x8080808080808080)
47#else
48#error long int is not a 32bit or 64bit type.
49#endif
50#endif
51_PTR
52_DEFUN (memccpy, (dst0, src0, endchar, len0),
53 _PTR __restrict dst0 _AND
54 _CONST _PTR __restrict src0 _AND
55 int endchar0 _AND
56 size_t len0)
57{
58#if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__)
59 _PTR ptr = NULL;
60 char *dst = (char *) dst0;
61 char *src = (char *) src0;
62 char endchar = endchar0 & 0xff;
63 while (len0--)
64 {
65 if ((*dst++ = *src++) == endchar)
66 {
67 ptr = dst;
68 break;
69 }
70 }
71 return ptr;
72#else
73 _PTR ptr = NULL;
74 char *dst = dst0;
75 _CONST char *src = src0;
76 long *aligned_dst;
77 _CONST long *aligned_src;
78 char endchar = endchar0 & 0xff;
79 /* If the size is small, or either SRC or DST is unaligned,
80 then punt into the byte copy loop. This should be rare. */
81 if (!TOO_SMALL(len0) && !ROCKBOX_UNALIGNED (src, dst))
82 {
83 unsigned int i;
84 unsigned long mask = 0;
85 aligned_dst = (long*)dst;
86 aligned_src = (long*)src;
87 /* The fast code reads the ASCII one word at a time and only
88 performs the bytewise search on word-sized segments if they
89 contain the search character, which is detected by XORing
90 the word-sized segment with a word-sized block of the search
91 character and then detecting for the presence of NULL in the
92 result. */
93 for (i = 0; i < LITTLEBLOCKSIZE; i++)
94 mask = (mask << 8) + endchar;
95 /* Copy one long word at a time if possible. */
96 while (len0 >= LITTLEBLOCKSIZE)
97 {
98 unsigned long buffer = (unsigned long)(*aligned_src);
99 buffer ^= mask;
100 if (DETECTNULL (buffer))
101 break; /* endchar is found, go byte by byte from here */
102 *aligned_dst++ = *aligned_src++;
103 len0 -= LITTLEBLOCKSIZE;
104 }
105 /* Pick up any residual with a byte copier. */
106 dst = (char*)aligned_dst;
107 src = (char*)aligned_src;
108 }
109 while (len0--)
110 {
111 if ((*dst++ = *src++) == endchar)
112 {
113 ptr = dst;
114 break;
115 }
116 }
117 return ptr;
118#endif /* not PREFER_SIZE_OVER_SPEED */
119}