function sub( x, y ) {
	// Cast `x` and `y` to signed 32-bit integers and apply a mask which keeps only the lowest 16 bits:
	return ( (x|0) - (y|0) ) & MASK;
}
Subtracts two unsigned 16-bit integers `x` and `y`.

@param {integer} x - first input value
@param {integer} y - second input value
@returns {integer} result

@example
var v = sub( 5, 1 );
// returns 4

@example
var v = sub( 5, 2 );
// returns 3

@example
var v = sub( 5, 0 );
// returns 5