1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
|
// Betting on GCC aligning this for efficiency.
#include <stdio.h>
int main()
{
unsigned short int read_16 = 0xF1F2;
unsigned int read_32 = 0xF1F2F3F4;
unsigned short int write_16 = 0xF00D;
unsigned int write_32 = 0xF00DFEED;
// 16bit unsigned reads, we expect 0xF1F2 and 0xF20000F1
fprintf(stderr, "%04x %04x\n",
*((unsigned short int *)((char *)&read_16)),
*((unsigned short int *)((char *)&read_16 + 1)));
// 16bit signed reads, we expect 0xFFFFF1F2 and 0xFFFFFFF1
fprintf(stderr, "%04x %04x\n",
*((short int *)((char *)&read_16)),
*((short int *)((char *)&read_16 + 1)));
// 32bit reads, we expect 0xF1F2F3F4, 0xF4F1F2F3, 0xF3F4F1F2,
// and 0xF2F3F4F1
fprintf(stderr, "%08x %08x %08x %08x\n",
*((int *)((char *)&read_32)),
*((int *)((char *)&read_32 + 1)),
*((int *)((char *)&read_32 + 2)),
*((int *)((char *)&read_32 + 3)));
// 16bit writes, we expect write_16 to remain 0xF00D
*((short int *)((char *)&write_16)) = 0xF00D;
*((short int *)((char *)&write_16) + 1) = 0xF00D;
fprintf(stderr, "%04x\n", write_16);
// 32bit writes, we expect write_32 to remain 0xF00DFEED
*((int *)((char *)&write_16)) = 0xF00DFEED;
*((int *)((char *)&write_16) + 1) = 0xF00DFEED;
*((int *)((char *)&write_16) + 2) = 0xF00DFEED;
*((int *)((char *)&write_16) + 3) = 0xF00DFEED;
fprintf(stderr, "%08x\n", write_32);
return 0;
}
|
