src/sha256-001.js
function xor() {
	var args = [].slice.call(arguments),
		bits = args.shift().slice();
	args.forEach(function(arg, y) {
		arg.forEach(function(bit, x) {
			bits[x] ^= bit;
		});
	});
	return bits;
}
function xor() {
	var args = [].slice.call(arguments),
		bits = args.shift().slice();
	args.forEach(function(arg, y) {
		arg.forEach(function(bit, x) {
			bits[x] ^= bit;
		});
	});
	return bits;
}
/* exclusive or all arguments (arrays of bits)