Javascript Prime-Generator (Atkins-Sieve)

atkinssieve.js

atkinsSieve = function (e) {
        last = 0;
        for (var d = Array(e + 1), a = 0; a < d.length; a++) d[a] = 0;
        for (var f = Math.floor(Math.sqrt(e)) + 1, b, c, a = 1; a < f; a++) for (c = 1; c < f; c++) {
                        b = 4 * Math.pow(a, 2) + Math.pow(c, 2);
                        if (b <= e && (1 === b % 12 || 5 === b % 12)) d[b] ^= 1;
                        b = 3 * Math.pow(a, 2) + Math.pow(c, 2);
                        b <= e && 7 === b % 12 && (d[b] ^= 1);
                        a > c && (b = 3 * Math.pow(a, 2) - Math.pow(c, 2), b <= e && 11 === b % 12 && (d[b] ^= 1))
        }
        for (a = 5; a < f; a++) if (1 === d[a]) for (c = Math.pow(a, 2); c < e; c += Math.pow(a, 2)) d[c] = 0;
        for (a = 7; a < e; a++) 1 === d[a] && (last = a);
        return last
};