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

#include "DarkNoise.h"

#ifdef SHR3D_SFX_CORE_AIRWINDOWS

namespace airwinconsolidated::DarkNoise {

void DarkNoise::processBlock(float **inputs, float **outputs, int sampleFrames) 
{
    float* in1  =  inputs[0];
    float* in2  =  inputs[1];
    float* out1 = outputs[0];
    float* out2 = outputs[1];
	
	int freqTarget = (int)(pow(A,3)*8192.0);
	if (freqTarget < 2) freqTarget = 2;
	double volumeScale = (1.0/freqTarget) * sqrt(freqTarget);
	
	double overalltaps = (pow(A,2)*8.0)+2.0;
	double taps = overalltaps;
	//this is our averaging, which is not integer but continuous
	
	double overallpoles = (A*9.0)+1.0;
	//this is the poles of the filter, also not integer but continuous
	int yLimit = floor(overallpoles)+1;
	double yPartial = overallpoles - floor(overallpoles);
	//now we can do a for loop, and also apply the final pole continuously
	int xLimit = 1;
	for(int x = 0; x < 11; x++) {
		if (taps > 1.0) {
			f[x] = 1.0;
			taps -= 1.0;
			xLimit++;
		} else {
			f[x] = taps;
			taps = 0.0;
		}
	} //there, now we have a neat little moving average with remainders
	if (xLimit > 9) xLimit = 9;
	
	if (overalltaps < 1.0) overalltaps = 1.0;
	for(int x = 0; x < xLimit; x++) {
		f[x] /= overalltaps;
	} //and now it's neatly scaled, too	
	
	double dark  = B;
	double out  = C*0.5;
	double wet = D;
    
    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;
		double drySampleL = inputSampleL;
		double drySampleR = inputSampleR;
		
		if (freqTarget < freq) {
			outputNoiseL = ((outputNoiseL-0.5)*(1.0-(1.0/freq)))+0.5;
			outputNoiseR = ((outputNoiseR-0.5)*(1.0-(1.0/freq)))+0.5;
			rL[freq] = 0.5;
			rR[freq] = 0.5;
			freq--;
		}
		if (freqTarget > freq) freq++;
		//our tone control chases the input one bin at a time
		
		double randyL = (double)fpdL / UINT32_MAX;
		double randyR = (double)fpdR / UINT32_MAX;
		// 0 to 1 random value
		
		int replacementBinL = randyL * freq;
		outputNoiseL -= rL[replacementBinL];
		rL[replacementBinL] = lastRandyL;
		outputNoiseL += lastRandyL;
		lastRandyL = randyL;
		//we update only one of the slots we're using
		
		int replacementBinR = randyR * freq;
		outputNoiseR -= rR[replacementBinR];
		rR[replacementBinR] = lastRandyR;
		outputNoiseR += lastRandyR;
		lastRandyR = randyR;
		//we update only one of the slots we're using
		
		inputSampleL = (-0.5 + outputNoiseL) * volumeScale;
		inputSampleR = (-0.5 + outputNoiseR) * volumeScale;
		
		double nondarkSampleL = inputSampleL;
		double nondarkSampleR = inputSampleR;
		
		double previousPoleL = 0;		
		double previousPoleR = 0;		
		for (int y = 0; y < yLimit; y++) {
			for (int x = xLimit; x >= 0; x--) {bL[x+1][y] = bL[x][y]; bR[x+1][y] = bR[x][y];}
			bL[0][y] = previousPoleL = inputSampleL;
			bR[0][y] = previousPoleR = inputSampleR;
			inputSampleL = 0.0;
			inputSampleR = 0.0;
			for (int x = 0; x < xLimit; x++) {inputSampleL += (bL[x][y] * f[x]);inputSampleR += (bR[x][y] * f[x]);}
		}
		inputSampleL = (previousPoleL * (1.0-yPartial)) + (inputSampleL * yPartial);
		inputSampleR = (previousPoleR * (1.0-yPartial)) + (inputSampleR * yPartial);
		//in this way we can blend in the final pole
				
		if (dark !=1.0) {
			inputSampleL = (inputSampleL * dark) + (nondarkSampleL * (1.0-dark));
			inputSampleR = (inputSampleR * dark) + (nondarkSampleR * (1.0-dark));
		}
		if (out !=1.0) {
			inputSampleL *= out;
			inputSampleR *= out;
		}
		
		if (wet !=1.0) {
			inputSampleL = (inputSampleL * wet) + (drySampleL * (1.0-wet));
			inputSampleR = (inputSampleR * wet) + (drySampleR * (1.0-wet));
		}
		//Dry/Wet control, defaults to the last slider
		
		//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
