This is an "aired-out" version of Mark Sheppard's 145 bytes quicksort

quicksort_aired_out.c

/*
 * This is an "aired-out" version of Mark Sheppard's
 * 145 bytes quicksort, also found on GitHub Gist:
 * https://gist.github.com/marksheppard/31cd41b527efe1187983
 */

s(*l, n)
{
        int i, j;
        if(n > 1) {
                for(i = -1, j = n;; ++i, --j) {
                        while(l[++i] < l[1]);
                        while(l[1] < l[--j]);
                        if(i >= j) break;
                        l[j] += l[i] - (l[i] = l[j]);
                };
                s(l, i);
                s(l + i, n - i);
        }
}