47 lines
1,008 B
C
47 lines
1,008 B
C
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#include "trap.h"
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typedef unsigned char uint8_t;
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__attribute__((noinline))
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bool getbit(void *buf, int offset){
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int byte = offset >> 3;
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offset &= 7;
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uint8_t mask = 1 << offset;
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return (((uint8_t *)buf)[byte] & mask) != 0;
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}
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__attribute__((noinline))
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void setbit(void *buf, int offset, bool bit){
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int byte = offset >> 3;
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offset &= 7;
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uint8_t mask = 1 << offset;
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uint8_t * volatile p = buf + byte;
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*p = (bit == 0 ? (*p & ~mask) : (*p | mask));
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}
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int main() {
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uint8_t buf[2];
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buf[0] = 0xaa;
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buf[1] = 0x0;
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nemu_assert(getbit(buf, 0) == 0);
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nemu_assert(getbit(buf, 1) == 1);
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nemu_assert(getbit(buf, 2) == 0);
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nemu_assert(getbit(buf, 3) == 1);
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nemu_assert(getbit(buf, 4) == 0);
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nemu_assert(getbit(buf, 5) == 1);
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nemu_assert(getbit(buf, 6) == 0);
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nemu_assert(getbit(buf, 7) == 1);
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setbit(buf, 8, 1);
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setbit(buf, 9, 0);
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setbit(buf, 10, 1);
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setbit(buf, 11, 0);
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setbit(buf, 12, 1);
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setbit(buf, 13, 0);
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setbit(buf, 14, 1);
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setbit(buf, 15, 0);
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nemu_assert(buf[1] == 0x55);
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return 0;
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}
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