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 <<memcpy>>---copy memory regions
4
5ANSI_SYNOPSIS
6 #include <string.h>
7 void* memcpy(void *<[out]>, const void *<[in]>, size_t <[n]>);
8
9TRAD_SYNOPSIS
10 void *memcpy(<[out]>, <[in]>, <[n]>
11 void *<[out]>;
12 void *<[in]>;
13 size_t <[n]>;
14
15DESCRIPTION
16 This function copies <[n]> bytes from the memory region
17 pointed to by <[in]> to the memory region pointed to by
18 <[out]>.
19
20 If the regions overlap, the behavior is undefined.
21
22RETURNS
23 <<memcpy>> returns a pointer to the first byte of the <[out]>
24 region.
25
26PORTABILITY
27<<memcpy>> is ANSI C.
28
29<<memcpy>> requires no supporting OS subroutines.
30
31QUICKREF
32 memcpy ansi pure
33 */
34
35#include "config.h"
36#include "_ansi.h" /* for _DEFUN */
37#include <string.h>
38
39/* Nonzero if either X or Y is not aligned on a "long" boundary. */
40#define ROCKBOX_UNALIGNED(X, Y) \
41 (((long)X & (sizeof (long) - 1)) | ((long)Y & (sizeof (long) - 1)))
42
43/* How many bytes are copied each iteration of the 4X unrolled loop. */
44#define BIGBLOCKSIZE (sizeof (long) << 2)
45
46/* How many bytes are copied each iteration of the word copy loop. */
47#define LITTLEBLOCKSIZE (sizeof (long))
48
49/* Threshold for punting to the byte copier. */
50#define TOO_SMALL(LEN) ((LEN) < BIGBLOCKSIZE)
51
52_PTR
53_DEFUN (memcpy, (dst0, src0, len0),
54 _PTR dst0 _AND
55 _CONST _PTR src0 _AND
56 size_t len0) ICODE_ATTR;
57
58_PTR
59_DEFUN (memcpy, (dst0, src0, len0),
60 _PTR dst0 _AND
61 _CONST _PTR src0 _AND
62 size_t len0)
63{
64#if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__)
65 char *dst = (char *) dst0;
66 char *src = (char *) src0;
67
68 _PTR save = dst0;
69
70 while (len0--)
71 {
72 *dst++ = *src++;
73 }
74
75 return save;
76#else
77 char *dst = dst0;
78 _CONST char *src = src0;
79 long *aligned_dst;
80 _CONST long *aligned_src;
81 unsigned int len = len0;
82
83 /* If the size is small, or either SRC or DST is unaligned,
84 then punt into the byte copy loop. This should be rare. */
85 if (!TOO_SMALL(len) && !ROCKBOX_UNALIGNED (src, dst))
86 {
87 aligned_dst = (long*)dst;
88 aligned_src = (long*)src;
89
90 /* Copy 4X long words at a time if possible. */
91 while (len >= BIGBLOCKSIZE)
92 {
93 *aligned_dst++ = *aligned_src++;
94 *aligned_dst++ = *aligned_src++;
95 *aligned_dst++ = *aligned_src++;
96 *aligned_dst++ = *aligned_src++;
97 len -= (unsigned int)BIGBLOCKSIZE;
98 }
99
100 /* Copy one long word at a time if possible. */
101 while (len >= LITTLEBLOCKSIZE)
102 {
103 *aligned_dst++ = *aligned_src++;
104 len -= LITTLEBLOCKSIZE;
105 }
106
107 /* Pick up any residual with a byte copier. */
108 dst = (char*)aligned_dst;
109 src = (char*)aligned_src;
110 }
111
112 while (len--)
113 *dst++ = *src++;
114
115 return dst0;
116#endif /* not PREFER_SIZE_OVER_SPEED */
117}