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

#include "DoublePaul.h"

#ifdef SHR3D_SFX_CORE_AIRWINDOWS

namespace airwinconsolidated::DoublePaul {

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

	double currentDitherL;
	double currentDitherR;

	double inputSampleL;
	double inputSampleR;
	    
    while (--sampleFrames >= 0)
    {
		inputSampleL = *in1;
		inputSampleR = *in2;
		if (fabs(inputSampleL)<1.18e-23) inputSampleL = fpdL * 1.18e-17;
		if (fabs(inputSampleR)<1.18e-23) inputSampleR = fpdR * 1.18e-17;

		inputSampleL *= 8388608.0;
		inputSampleR *= 8388608.0;
		//0-1 is now one bit, now we dither
		
		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] = (double(fpdL)/UINT32_MAX);
		
		currentDitherL  = (bL[0] * 0.061);
		currentDitherL -= (bL[1] * 0.11);
		currentDitherL += (bL[8] * 0.126);
		currentDitherL -= (bL[7] * 0.23);
		currentDitherL += (bL[2] * 0.25);
		currentDitherL -= (bL[3] * 0.43);
		currentDitherL += (bL[6] * 0.5);
		currentDitherL -= bL[5];
		currentDitherL += bL[4];
		//this sounds different from doing it in order of sample position
		//cumulative tiny errors seem to build up even at this buss depth
		//considerably more pronounced at 32 bit float.
		//Therefore we add the most significant components LAST.
		//trying to keep values on like exponents of the floating point value.
		inputSampleL += currentDitherL;
		
		inputSampleL = floor(inputSampleL);
			//done with L
		
		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] = (double(fpdR)/UINT32_MAX);
		
		currentDitherR  = (bR[0] * 0.061);
		currentDitherR -= (bR[1] * 0.11);
		currentDitherR += (bR[8] * 0.126);
		currentDitherR -= (bR[7] * 0.23);
		currentDitherR += (bR[2] * 0.25);
		currentDitherR -= (bR[3] * 0.43);
		currentDitherR += (bR[6] * 0.5);
		currentDitherR -= bR[5];
		currentDitherR += bR[4];
		//this sounds different from doing it in order of sample position
		//cumulative tiny errors seem to build up even at this buss depth
		//considerably more pronounced at 32 bit float.
		//Therefore we add the most significant components LAST.
		//trying to keep values on like exponents of the floating point value.
		inputSampleR += currentDitherR;
		
		inputSampleR = floor(inputSampleR);
			//done with R
		
		inputSampleL /= 8388608.0;
		inputSampleR /= 8388608.0;
		
		fpdL ^= fpdL << 13; fpdL ^= fpdL >> 17; fpdL ^= fpdL << 5;
		fpdR ^= fpdR << 13; fpdR ^= fpdR >> 17; fpdR ^= fpdR << 5;
		//pseudorandom number updater

		*out1 = float(inputSampleL);
		*out2 = float(inputSampleR);

		in1++;
		in2++;
		out1++;
		out2++;
    }
}

} // end namespace

#endif // SHR3D_SFX_CORE_AIRWINDOWS
