pop_count
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#include <stdio.h>
unsigned pop_count(unsigned a) {
unsigned b = (a & 0x55555555) + ((a & 0xAAAAAAAA) >> 1);
unsigned c = (b & 0x33333333) + ((b & 0xCCCCCCCC) >> 2);
unsigned d = (c & 0x0F0F0F0F) + ((c & 0xF0F0F0F0) >> 4);
unsigned e = (d & 0x00FF00FF) + ((d & 0xFF00FF00) >> 8);
unsigned f = (e & 0x0000FFFF) + ((e & 0xFFFF0000) >> 16);
return f;
}
int main(void) {
printf("%u\n", pop_count(0xFFFFFFFF));
printf("%u\n", pop_count(0));
printf("%u\n", pop_count(0xFFF0FFFF));
return 0;
}
C
INFO