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bitvector-using-bit-op.c
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bitvector-using-bit-op.c
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/*
* bitvector-using-bit-op.c
* Implement set(), clear() and test() with bit operations, like AND, OR, or SHIFT
*/
#include <stdio.h>
#include <string.h>
#define BITS 1000
#define BITSPERWORD 32
#define SHIFT 5
int a[1 + BITS/BITSPERWORD];
#define set(i) a[(i) >> SHIFT] |= 1 << ((i) & (BITSPERWORD - 1))
#define clear(i) a[(i) >> SHIFT] &= ~(1 << ((i) & (BITSPERWORD - 1)))
#define test(i) a[(i) >> SHIFT] & (1 << ((i) & (BITSPERWORD - 1)))
void init()
{
memset(a, 0, sizeof(a));
}
void print()
{
int i;
int j;
for (i = 0; i < sizeof(a) / sizeof(int); i += 4) {
for (j = 0; j < 4; j++) {
printf("0x%08x ", a[i + j]);
}
printf("\n");
}
printf("\n");
return;
}
int main()
{
set(0);
set(10);
set(35);
set(48);
print();
clear(10);
print();
printf("bit 0 %s\n", test(0) ? "set" : "not set");
printf("bit 10 %s\n", test(10) ? "set" : "not set");
printf("bit 35 %s\n", test(35) ? "set" : "not set");
printf("bit 48 %s\n", test(48) ? "set" : "not set");
return 0;
}