function interleaveBit(bit, len) {
    let h = Math.ceil(len / 2);
    let group = Math.floor(bit / h);
    let stride = bit % h;
    return stride * 2 + group;
}
Transforms from a block bit position to a striped bit position.
@param {!int} bit
@param {!int} len
@returns {!int}