Obfuscated FizzBuzz in C

#include <stdio.h>

/*
 * Write a program that prints the numbers from 1 to 100. But for multiples of
 * three print "Fizz" instead of the number and for the multiples of five
 * print "Buzz". For numbers which are multiples of both three and five print
 * "FizzBuzz".
 */

#define CHECK_MULT(num) (((buf = (float) index / num) == (int) buf) << (num / 5))

int main(int argc, char **argv) {
    float buf;
    int index;
    unsigned char mult;

    for(index = 1; index <= 100; index++) {
        mult = 0;
        if(((mult |= CHECK_MULT(3)) & 1))
            printf("Fizz");
        if(((mult |= CHECK_MULT(5)) & 2))
            printf("Buzz");
        if(!mult)
            printf("%i", index);

        puts("");
    }

    return 0;
}