/**
* Converts the floating point value to its exponent-mantissa representation. The mantissa
* occupies the 11 least significant bits (bits 10-0), and the exponent the previous 5 bits (bits
* 15-11).
*
* @param step The quantization step, normalized to a dynamic range of 1.
* @return The exponent mantissa representation of the step.
*/
public static int convertToExpMantissa(float step) {
int exp;
exp = (int) Math.ceil(-Math.log(step) / log2);
if (exp > QSTEP_MAX_EXPONENT) {
// If step size is too small for exponent representation, use the
// minimum, which is exponent QSTEP_MAX_EXPONENT and mantissa 0.
return (QSTEP_MAX_EXPONENT << QSTEP_MANTISSA_BITS);
}
// NOTE: this formula does not support more than 5 bits for the
// exponent, otherwise (-1<<exp) might overflow (the - is used to be
// able to represent 2**31)
return (exp << QSTEP_MANTISSA_BITS)
| ((int) ((-step * (-1 << exp) - 1f) * (1 << QSTEP_MANTISSA_BITS) + 0.5f));
}
