C++ function to normalize 8bit input into [-1 1] range with a deadzone in the middle.

normalize

// Normalizes a 8 bit integer value into [-1 1] range.
// The deadzone is the middle portion of the 8 bit range
// to be considered as 0 output. For a deadzone [dz] value
// of n, the deadzone range will be [127-n 128+n].
//
// in  =     0       (127 - dz)     (128 + dz)    255
// out =    -1           0              0          1
//       <---x-----------x--------------x----------x--->
//                       |______________|
//                            2 * dz
//
float normalize(uint8_t value, uint8_t deadzone) {
	// lower and upper zone boundaries
	uint8_t lz = 127 - deadzone;
	uint8_t uz = 128 + deadzone;
	
	// the [lz uz] range is the deadzone range
	if (value >= lz && value <= uz) {
		return 0;
	}

	// value is in [0 lz) range
	if (value < lz) {
		short sValue = (short)value - lz;
		float nValue = (float)sValue / (lz);

		return nValue;
	}
	else /* value is in (uz 255] range */ {
		short sValue = (short)value - uz;
		float nValue = (float)sValue / (lz);

		return nValue;
	}
}