快速遍历变量中所有置1位

#include <stdio.h>

int main(int argc, char *argv[])
{
    int mask = 0x8039;
    while (mask) {
        int i = 31 - __builtin_clz(mask);
        mask &= ~(1<<i);
        printf("[%d]\n", i);
    }
    return 0;
}

lutherge@wiki-server:~/tmp$ ./a.out
[15]
[5]
[4]
[3]
[0]