49 lines
1.4 KiB
C
49 lines
1.4 KiB
C
// Betting on GCC aligning this for efficiency.
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#include <stdio.h>
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int main()
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{
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unsigned short int read_16 = 0xF1F2;
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unsigned int read_32 = 0xF1F2F3F4;
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unsigned short int write_16 = 0xF00D;
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unsigned int write_32 = 0xF00DFEED;
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// 16bit unsigned reads, we expect 0xF1F2 and 0xF20000F1
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fprintf(stderr, "%04x %04x\n",
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*((unsigned short int *)((char *)&read_16)),
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*((unsigned short int *)((char *)&read_16 + 1)));
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// 16bit signed reads, we expect 0xFFFFF1F2 and 0xFFFFFFF1
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fprintf(stderr, "%04x %04x\n",
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*((short int *)((char *)&read_16)),
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*((short int *)((char *)&read_16 + 1)));
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// 32bit reads, we expect 0xF1F2F3F4, 0xF4F1F2F3, 0xF3F4F1F2,
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// and 0xF2F3F4F1
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fprintf(stderr, "%08x %08x %08x %08x\n",
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*((int *)((char *)&read_32)),
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*((int *)((char *)&read_32 + 1)),
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*((int *)((char *)&read_32 + 2)),
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*((int *)((char *)&read_32 + 3)));
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// 16bit writes, we expect write_16 to remain 0xF00D
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*((short int *)((char *)&write_16)) = 0xF00D;
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*((short int *)((char *)&write_16) + 1) = 0xF00D;
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fprintf(stderr, "%04x\n", write_16);
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// 32bit writes, we expect write_32 to remain 0xF00DFEED
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*((int *)((char *)&write_16)) = 0xF00DFEED;
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*((int *)((char *)&write_16) + 1) = 0xF00DFEED;
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*((int *)((char *)&write_16) + 2) = 0xF00DFEED;
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*((int *)((char *)&write_16) + 3) = 0xF00DFEED;
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fprintf(stderr, "%08x\n", write_32);
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return 0;
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}
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