/* ========================================
 *  PurestFade - PurestFade.h
 *  Copyright (c) 2016 airwindows, Airwindows uses the MIT license
 * ======================================== */

#include "PurestFade.h"

#ifdef SHR3D_SFX_CORE_AIRWINDOWS

namespace airwinconsolidated::PurestFade {

void PurestFade::processBlock(float **inputs, float **outputs, int sampleFrames) 
{
    float* in1  =  inputs[0];
    float* in2  =  inputs[1];
    float* out1 = outputs[0];
    float* out2 = outputs[1];

	double inputgain = (A * 80.0)-40.0;
	if (settingchase != inputgain) {
		chasespeed *= 2.0;
		settingchase = inputgain;
		//increment the slowness for each fader movement
		//continuous alteration makes it react smoother
		//sudden jump to setting, not so much
	}
	if (chasespeed > 2500.0) chasespeed = 2500.0;
	//bail out if it's too extreme
	if (gainchase < -60.0) {
		gainchase = pow(10.0,inputgain/20.0);
		//shouldn't even be a negative number
		//this is about starting at whatever's set, when
		//plugin is instantiated.
		//Otherwise it's the target, in dB.
	}
	double targetgain;	
	//done with top controller
	double targetBgain = B;
	if (gainBchase < 0.0) gainBchase = targetBgain;
	//this one is not a dB value, but straight multiplication
	//done with slow fade controller
	
	double fadeSpeed = targetBgain;
	if (fadeSpeed < 0.0027) fadeSpeed = 0.0027; //minimum fade speed
	fadeSpeed = ((getSampleRate()*0.004) / fadeSpeed);
	//this will tend to be much slower than PurestGain, and also adapt to sample rates
		
	double outputgain;
	
    while (--sampleFrames >= 0)
    {
		double inputSampleL = *in1;
		double inputSampleR = *in2;
		if (fabs(inputSampleL)<1.18e-23) inputSampleL = fpdL * 1.18e-17;
		if (fabs(inputSampleR)<1.18e-23) inputSampleR = fpdR * 1.18e-17;

		targetgain = pow(10.0,settingchase/20.0);
		//now we have the target in our temp variable
		
		chasespeed *= 0.9999;
		chasespeed -= 0.01;
		if (chasespeed < 350.0) chasespeed = 350.0;
		//we have our chase speed compensated for recent fader activity
		
		gainchase = (((gainchase*chasespeed)+targetgain)/(chasespeed+1.0));
		//gainchase is chasing the target, as a simple multiply gain factor
		
		gainBchase = (((gainBchase*fadeSpeed)+targetBgain)/(fadeSpeed+1.0));
		//gainchase is chasing the target, as a simple multiply gain factor
		
		outputgain = gainchase * gainBchase;
		//directly multiply the dB gain by the straight multiply gain
		
		if (1.0 == outputgain)
		{
			*out1 = *in1;
			*out2 = *in2;
		} else {
			inputSampleL *= outputgain;
			inputSampleR *= outputgain;
			
			//begin 32 bit stereo floating point dither
			int expon; frexpf((float)inputSampleL, &expon);
			fpdL ^= fpdL << 13; fpdL ^= fpdL >> 17; fpdL ^= fpdL << 5;
			inputSampleL += double((double(fpdL)-uint32_t(0x7fffffff)) * 5.5e-36l * pow(2.0,expon+62.0));
			frexpf((float)inputSampleR, &expon);
			fpdR ^= fpdR << 13; fpdR ^= fpdR >> 17; fpdR ^= fpdR << 5;
			inputSampleR += double((double(fpdR)-uint32_t(0x7fffffff)) * 5.5e-36l * pow(2.0,expon+62.0));
			//end 32 bit stereo floating point dither
			*out1 = float(inputSampleL);
			*out2 = float(inputSampleR);
		}
		in1++;
		in2++;
		out1++;
		out2++;
	}
}

} // end namespace

#endif // SHR3D_SFX_CORE_AIRWINDOWS
