function exponent( x ) {
	// Extract from the input value a higher order word (unsigned 32-bit integer) which contains the exponent:
	var high = getHighWord( x );

	// Apply a mask to isolate only the exponent bits and then shift off all bits which are part of the fraction:
	high = ( high & EXP_MASK ) >>> 20;

	// Remove the bias and return:
	return (high - BIAS)|0; // asm type annotation
}
Returns an integer corresponding to the unbiased exponent of a double-precision floating-point number.

@param {number} x - input value
@returns {integer32} unbiased exponent

@example
var exp = exponent( 3.14e-307 ); // => 2**-1019 ~ 1e-307
// returns -1019

@example
var exp = exponent( -3.14 );
// returns 1

@example
var exp = exponent( 0.0 );
// returns -1023

@example
var exp = exponent( NaN );
// returns 1024