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int bitcount(long i)
{
i = ((i & 0xAAAAAAAA) >> 1) + (i & 0x55555555);
i = ((i & 0xCCCCCCCC) >> 2) + (i & 0x33333333);
i = ((i & 0xF0F0F0F0) >> 4) + (i & 0x0F0F0F0F);
i = ((i & 0xFF00FF00) >> 8) + (i & 0x00FF00FF);
i = ((i & 0xFFFF0000) >> 16) + (i & 0x0000FFFF);
return (int)i;
}
#ifdef TEST
#include <stdio.h>
#include <stdlib.h>
#define plural_text(n) &"s"[(1 == (n))]
void main(int argc, char *argv[])
{
long n;
while(--argc)
{
int i;
n = atol(*++argv);
i = bitcount(n);
printf("%ld contains %d bit%s set\n",
n, i, plural_text(i));
}
}
#endif /* TEST */
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