source: azure_iot_hub/trunk/musl-1.1.18/src/string/memcpy.c@ 388

Last change on this file since 388 was 388, checked in by coas-nagasima, 5 years ago

Azure IoT Hub Device C SDK を使ったサンプルの追加
  • Property svn:eol-style set to native
  • Property svn:keywords set to Id
  • Property svn:mime-type set to text/x-csrc
File size: 2.6 KB
Line 
1#include <string.h>
2#include <stdint.h>
3#include <endian.h>
4
5void *memcpy(void *restrict dest, const void *restrict src, size_t n)
6{
7 unsigned char *d = dest;
8 const unsigned char *s = src;
9
10#ifdef __GNUC__
11
12#if __BYTE_ORDER == __LITTLE_ENDIAN
13#define LS >>
14#define RS <<
15#else
16#define LS <<
17#define RS >>
18#endif
19
20 typedef uint32_t __attribute__((__may_alias__)) u32;
21 uint32_t w, x;
22
23 for (; (uintptr_t)s % 4 && n; n--) *d++ = *s++;
24
25 if ((uintptr_t)d % 4 == 0) {
26 for (; n>=16; s+=16, d+=16, n-=16) {
27 *(u32 *)(d+0) = *(u32 *)(s+0);
28 *(u32 *)(d+4) = *(u32 *)(s+4);
29 *(u32 *)(d+8) = *(u32 *)(s+8);
30 *(u32 *)(d+12) = *(u32 *)(s+12);
31 }
32 if (n&8) {
33 *(u32 *)(d+0) = *(u32 *)(s+0);
34 *(u32 *)(d+4) = *(u32 *)(s+4);
35 d += 8; s += 8;
36 }
37 if (n&4) {
38 *(u32 *)(d+0) = *(u32 *)(s+0);
39 d += 4; s += 4;
40 }
41 if (n&2) {
42 *d++ = *s++; *d++ = *s++;
43 }
44 if (n&1) {
45 *d = *s;
46 }
47 return dest;
48 }
49
50 if (n >= 32) switch ((uintptr_t)d % 4) {
51 case 1:
52 w = *(u32 *)s;
53 *d++ = *s++;
54 *d++ = *s++;
55 *d++ = *s++;
56 n -= 3;
57 for (; n>=17; s+=16, d+=16, n-=16) {
58 x = *(u32 *)(s+1);
59 *(u32 *)(d+0) = (w LS 24) | (x RS 8);
60 w = *(u32 *)(s+5);
61 *(u32 *)(d+4) = (x LS 24) | (w RS 8);
62 x = *(u32 *)(s+9);
63 *(u32 *)(d+8) = (w LS 24) | (x RS 8);
64 w = *(u32 *)(s+13);
65 *(u32 *)(d+12) = (x LS 24) | (w RS 8);
66 }
67 break;
68 case 2:
69 w = *(u32 *)s;
70 *d++ = *s++;
71 *d++ = *s++;
72 n -= 2;
73 for (; n>=18; s+=16, d+=16, n-=16) {
74 x = *(u32 *)(s+2);
75 *(u32 *)(d+0) = (w LS 16) | (x RS 16);
76 w = *(u32 *)(s+6);
77 *(u32 *)(d+4) = (x LS 16) | (w RS 16);
78 x = *(u32 *)(s+10);
79 *(u32 *)(d+8) = (w LS 16) | (x RS 16);
80 w = *(u32 *)(s+14);
81 *(u32 *)(d+12) = (x LS 16) | (w RS 16);
82 }
83 break;
84 case 3:
85 w = *(u32 *)s;
86 *d++ = *s++;
87 n -= 1;
88 for (; n>=19; s+=16, d+=16, n-=16) {
89 x = *(u32 *)(s+3);
90 *(u32 *)(d+0) = (w LS 8) | (x RS 24);
91 w = *(u32 *)(s+7);
92 *(u32 *)(d+4) = (x LS 8) | (w RS 24);
93 x = *(u32 *)(s+11);
94 *(u32 *)(d+8) = (w LS 8) | (x RS 24);
95 w = *(u32 *)(s+15);
96 *(u32 *)(d+12) = (x LS 8) | (w RS 24);
97 }
98 break;
99 }
100 if (n&16) {
101 *d++ = *s++; *d++ = *s++; *d++ = *s++; *d++ = *s++;
102 *d++ = *s++; *d++ = *s++; *d++ = *s++; *d++ = *s++;
103 *d++ = *s++; *d++ = *s++; *d++ = *s++; *d++ = *s++;
104 *d++ = *s++; *d++ = *s++; *d++ = *s++; *d++ = *s++;
105 }
106 if (n&8) {
107 *d++ = *s++; *d++ = *s++; *d++ = *s++; *d++ = *s++;
108 *d++ = *s++; *d++ = *s++; *d++ = *s++; *d++ = *s++;
109 }
110 if (n&4) {
111 *d++ = *s++; *d++ = *s++; *d++ = *s++; *d++ = *s++;
112 }
113 if (n&2) {
114 *d++ = *s++; *d++ = *s++;
115 }
116 if (n&1) {
117 *d = *s;
118 }
119 return dest;
120#endif
121
122 for (; n; n--) *d++ = *s++;
123 return dest;
124}
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