/* ========================================
 *  Biquad2 - Biquad2.h
 *  Copyright (c) 2016 airwindows, Airwindows uses the MIT license
 * ======================================== */

#include "Biquad2.h"

#ifdef SHR3D_SFX_CORE_AIRWINDOWS

namespace airwinconsolidated::Biquad2 {

void Biquad2::processBlock(float **inputs, float **outputs, int sampleFrames) 
{
    float* in1  =  inputs[0];
    float* in2  =  inputs[1];
    float* out1 = outputs[0];
    float* out2 = outputs[1];

	double overallscale = 1.0;
	overallscale /= 44100.0;
	overallscale *= getSampleRate();
	
	int type = ceil((A*3.999)+0.00001);
	
	double average = B*B;
	double frequencytarget = average*0.39; //biquad[0], goes to 1.0
	frequencytarget /= overallscale;
	if (frequencytarget < 0.0015/overallscale) frequencytarget = 0.0015/overallscale;
    double resonancetarget = (C*C*49.99)+0.01; //biquad[1], goes to 50.0
	if (resonancetarget < 1.0) resonancetarget = 1.0;
	double outputtarget = D; //scaled to res
	if (type < 3) outputtarget /= sqrt(resonancetarget);
	double wettarget = (E*2.0)-1.0; //wet, goes -1.0 to 1.0
	
	//biquad contains these values:
	//[0] is frequency: 0.000001 to 0.499999 is near-zero to near-Nyquist
	//[1] is resonance, 0.7071 is Butterworth. Also can't be zero
	//[2] is a0 but you need distinct ones for additional biquad instances so it's here
	//[3] is a1 but you need distinct ones for additional biquad instances so it's here
	//[4] is a2 but you need distinct ones for additional biquad instances so it's here
	//[5] is b1 but you need distinct ones for additional biquad instances so it's here
	//[6] is b2 but you need distinct ones for additional biquad instances so it's here
	//[7] is a stored delayed sample (freq and res are stored so you can move them sample by sample)
	//[8] is a stored delayed sample (you have to include the coefficient making code if you do that)
	//[9] is a stored delayed sample (you have to include the coefficient making code if you do that)
	//[10] is a stored delayed sample (you have to include the coefficient making code if you do that)
	double K = tan(M_PI * biquad[0]);
	double norm = 1.0 / (1.0 + K / biquad[1] + K * K);
	//finished setting up biquad
	
	average = (1.0-average)*10.0; //max taps is 10, and low settings use more
	
	if (type == 1 || type == 3) average = 1.0;
	
	double gain = average;
	if (gain > 1.0) {f[0] = 1.0; gain -= 1.0;} else {f[0] = gain; gain = 0.0;}
	if (gain > 1.0) {f[1] = 1.0; gain -= 1.0;} else {f[1] = gain; gain = 0.0;}
	if (gain > 1.0) {f[2] = 1.0; gain -= 1.0;} else {f[2] = gain; gain = 0.0;}
	if (gain > 1.0) {f[3] = 1.0; gain -= 1.0;} else {f[3] = gain; gain = 0.0;}
	if (gain > 1.0) {f[4] = 1.0; gain -= 1.0;} else {f[4] = gain; gain = 0.0;}
	if (gain > 1.0) {f[5] = 1.0; gain -= 1.0;} else {f[5] = gain; gain = 0.0;}
	if (gain > 1.0) {f[6] = 1.0; gain -= 1.0;} else {f[6] = gain; gain = 0.0;}
	if (gain > 1.0) {f[7] = 1.0; gain -= 1.0;} else {f[7] = gain; gain = 0.0;}
	if (gain > 1.0) {f[8] = 1.0; gain -= 1.0;} else {f[8] = gain; gain = 0.0;}
	if (gain > 1.0) {f[9] = 1.0; gain -= 1.0;} else {f[9] = gain; gain = 0.0;}
	//there, now we have a neat little moving average with remainders
	
	if (average < 1.0) average = 1.0;
	f[0] /= average;
	f[1] /= average;
	f[2] /= average;
	f[3] /= average;
	f[4] /= average;
	f[5] /= average;
	f[6] /= average;
	f[7] /= average;
	f[8] /= average;
	f[9] /= average;
	//and now it's neatly scaled, too
	//finished setting up average
	
	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;
		
		double chasespeed = 50000;
		if (frequencychase < frequencytarget) chasespeed = 500000;
		chasespeed /= resonancechase;
		chasespeed *= overallscale;
		
		frequencychase = (((frequencychase*chasespeed)+frequencytarget)/(chasespeed+1.0));
				
		double fasterchase = 1000 * overallscale;		
		resonancechase = (((resonancechase*fasterchase)+resonancetarget)/(fasterchase+1.0));
		outputchase = (((outputchase*fasterchase)+outputtarget)/(fasterchase+1.0));
		wetchase = (((wetchase*fasterchase)+wettarget)/(fasterchase+1.0));
		if (biquad[0] != frequencychase) {biquad[0] = frequencychase; K = tan(M_PI * biquad[0]);}
		if (biquad[1] != resonancechase) {biquad[1] = resonancechase; norm = 1.0 / (1.0 + K / biquad[1] + K * K);}
		
		if (type == 1) { //lowpass
			biquad[2] = K * K * norm;
			biquad[3] = 2.0 * biquad[2];
			biquad[4] = biquad[2];
			biquad[5] = 2.0 * (K * K - 1.0) * norm;
		}
		
		if (type == 2) { //highpass
			biquad[2] = norm;
			biquad[3] = -2.0 * biquad[2];
			biquad[4] = biquad[2];
			biquad[5] = 2.0 * (K * K - 1.0) * norm;
		}
		
		if (type == 3) { //bandpass
			biquad[2] = K / biquad[1] * norm;
			biquad[3] = 0.0; //bandpass can simplify the biquad kernel: leave out this multiply
			biquad[4] = -biquad[2];
			biquad[5] = 2.0 * (K * K - 1.0) * norm;
		}
		
		if (type == 4) { //notch
			biquad[2] = (1.0 + K * K) * norm;
			biquad[3] = 2.0 * (K * K - 1) * norm;
			biquad[4] = biquad[2];
			biquad[5] = biquad[3];
		}
		
		biquad[6] = (1.0 - K / biquad[1] + K * K) * norm;
		
		inputSampleL = sin(inputSampleL);
		inputSampleR = sin(inputSampleR);
		//encode Console5: good cleanness
		
		double outSampleL = biquad[2]*inputSampleL+biquad[3]*biquad[7]+biquad[4]*biquad[8]-biquad[5]*biquad[9]-biquad[6]*biquad[10];
		biquad[8] = biquad[7]; biquad[7] = inputSampleL; inputSampleL = outSampleL; biquad[10] = biquad[9]; biquad[9] = inputSampleL; //DF1 left
		
		double outSampleR = biquad[2]*inputSampleR+biquad[3]*biquad[11]+biquad[4]*biquad[12]-biquad[5]*biquad[13]-biquad[6]*biquad[14];
		biquad[12] = biquad[11]; biquad[11] = inputSampleR; inputSampleR = outSampleR; biquad[14] = biquad[13]; biquad[13] = inputSampleR; //DF1 right
				
		if (inputSampleL > 1.0) inputSampleL = 1.0;
		if (inputSampleL < -1.0) inputSampleL = -1.0;
		if (inputSampleR > 1.0) inputSampleR = 1.0;
		if (inputSampleR < -1.0) inputSampleR = -1.0;
		
		bL[9] = bL[8]; bL[8] = bL[7]; bL[7] = bL[6]; bL[6] = bL[5];
		bL[5] = bL[4]; bL[4] = bL[3]; bL[3] = bL[2]; bL[2] = bL[1];
		bL[1] = bL[0]; bL[0] = inputSampleL;

		bR[9] = bR[8]; bR[8] = bR[7]; bR[7] = bR[6]; bR[6] = bR[5];
		bR[5] = bR[4]; bR[4] = bR[3]; bR[3] = bR[2]; bR[2] = bR[1];
		bR[1] = bR[0]; bR[0] = inputSampleR;
		
		inputSampleL *= f[0];
		inputSampleL += (bL[1] * f[1]);
		inputSampleL += (bL[2] * f[2]);
		inputSampleL += (bL[3] * f[3]);
		inputSampleL += (bL[4] * f[4]);
		inputSampleL += (bL[5] * f[5]);
		inputSampleL += (bL[6] * f[6]);
		inputSampleL += (bL[7] * f[7]);
		inputSampleL += (bL[8] * f[8]);
		inputSampleL += (bL[9] * f[9]); //intense averaging on deeper cutoffs
		
		inputSampleR *= f[0];
		inputSampleR += (bR[1] * f[1]);
		inputSampleR += (bR[2] * f[2]);
		inputSampleR += (bR[3] * f[3]);
		inputSampleR += (bR[4] * f[4]);
		inputSampleR += (bR[5] * f[5]);
		inputSampleR += (bR[6] * f[6]);
		inputSampleR += (bR[7] * f[7]);
		inputSampleR += (bR[8] * f[8]);
		inputSampleR += (bR[9] * f[9]); //intense averaging on deeper cutoffs
		
		if (inputSampleL > 1.0) inputSampleL = 1.0;
		if (inputSampleL < -1.0) inputSampleL = -1.0;
		if (inputSampleR > 1.0) inputSampleR = 1.0;
		if (inputSampleR < -1.0) inputSampleR = -1.0;
		//without this, you can get a NaN condition where it spits out DC offset at full blast!
		inputSampleL = asin(inputSampleL);
		inputSampleR = asin(inputSampleR);
		//amplitude aspect
		if (inputSampleL > 1.0) inputSampleL = 1.0;
		if (inputSampleL < -1.0) inputSampleL = -1.0;
		if (inputSampleR > 1.0) inputSampleR = 1.0;
		if (inputSampleR < -1.0) inputSampleR = -1.0;
		//and then Console5 will spit out overs if you let it
				
		if (outputchase < 1.0) {
			inputSampleL *= outputchase;
			inputSampleR *= outputchase;
		}
		
		if (wetchase < 1.0) {
			inputSampleL = (inputSampleL*wetchase) + (drySampleL*(1.0-fabs(wetchase)));
			inputSampleR = (inputSampleR*wetchase) + (drySampleR*(1.0-fabs(wetchase)));
			//inv/dry/wet lets us turn LP into HP and band into notch
		}
		
		//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
