Number.toGrayCode = function(n) {
    if (n < 0) {
        throw new RangeError("cannot convert negative numbers to gray code");
    }
    return n ^ (n >>> 1);
};

Number.fromGrayCode = function(gn) {
    if (gn < 0) {
        throw new RangeError("gray code numbers cannot be negative");
    }
    var mask;
    for (mask = gn >> 1; mask != 0; mask = mask >> 1) {
        gn ^= mask;
    }
    return gn;
};