A test of bitwise and used to increment and wrap access into an array in doom's event-handling.

bitwise_and_test.c

#include<stdio.h>

int main() {
    int SIZE = 10;
    int head = 0;
    int tail = 0;

    head = 3;
    tail = 5;

    printf("size-1: %d, head: %d, tail: %d, tail&SIZE-1: %d\n", SIZE-1, head, tail, tail&(SIZE-1));
    for(; tail != head; tail = (++tail)&(SIZE-1)) {
        printf("size-1: %d, head: %d, tail: %d, tail&SIZE-1: %d\n", SIZE-1, head, tail, tail&(SIZE-1));
    }
    printf("size-1: %d, head: %d, tail: %d, tail&SIZE-1: %d\n", SIZE-1, head, tail, tail&(SIZE-1));

    return 0;
}