A little function to take a value in the range 0-x and convert them to values in a different, smaller range.

num_range_shrink.c

unsigned int num_range_shrink(unsigned int orig, unsigned int old_limit, unsigned int new_upper) {
    float interval = old_limit / new_upper;
    for(int i = 1; i <= new_upper; i++) {
        if(orig < i*interval) {
            return i-1;
        }
    }
    return 0;
}