fgdata/Nasal/bits.nas

var bit = [var _ = 1];
for (var i = 1; i < 32; i += 1)
	append(bit, _ += _);


# returns number <n> as bit string: bits.string(6) -> "110"
var string = func(n) {
	if (!n)
		return '0';
	var s = "";
	while (n) {
		s = ((var v = int(n / 2)) + v != n) ~ s;
		n = v;
	}
	return s;
}


# checks whether bit <b> is set in number <n>
var test = func(n, b) {
	n /= bit[b];
	return int(n) != int(n / 2) * 2;
}


# returns number <n> with bit <b> set
var set = func(n, b) test(n, b) ? n : n + bit[b];


# returns number <n> with bit <b> cleared
var clear = func(n, b) test(n, b) ? n - bit[b] : n;


# returns number <n> with bit <b> toggled
var toggle = func(n, b) test(n, b) ? n - bit[b] : n + bit[b];


# returns number <n> with bit <b> set to value <v>
var switch = func(n, b, v) n - (test(n, b) - !!v) * bit[b];