audio_lab_software.c

// Filtering function using 2 for loops instead of one with a modulo because it turned out to be way more efficient
// indexVal is the position of the current sample, it decreases each loop but staying in [0;currentSize]
void filter(){

	for(int w = indexVal ; w < currentSize ; w++){
		toReturn[0] += currentCoeffs[w-indexVal] * bufferL[w];
		toReturn[1] += currentCoeffs[w-indexVal] * bufferR[w];
	}

	for(int l = 0 ; l < indexVal ; l++){
		toReturn[0] += currentCoeffs[currentSize-indexVal+l] * bufferL[l];
		toReturn[1] += currentCoeffs[currentSize-indexVal+l] * bufferR[l];
	}


}

// Changing the used filter by changing the used coefficients and the number of them (currentSize)
void applyFilter(int filter){
	switch(filter){
	case 0: // Basic HP
		currentCoeffs = HP;
		currentSize = N_HP;
		break;

	case 1: // Basic LP
		currentCoeffs = LP;
		currentSize = N_LP;
		break;

	case 2: // None
		currentCoeffs = None;
		currentSize = N_None;
		break;

	case 3: // LP 2
		currentCoeffs = LP2;
		currentSize = N_LP2;
		break;

	case 99:
		currentCoeffs = F99;
		currentSize = N_F99;
		break;
	}

	indexVal = currentSize-1;
}




int main()
{

	init_platform();

	print("Started!\n\r");

	AudioInitialize(SCU_TIMER_ID, AUDIO_IIC_ID, AUDIO_CTRL_BASEADDR);

	initialize_FIFO(AUDIO_FIFO);
	initialize_FIFO(FIR_FIFO);

	applyFilter(99);



	int SampleL, SampleR;


	int j=0;
	int time_now=0;
	int time_func = 0;
	int t = 0;

	int tim_now_filter = 0;

	int currentFilter = 0;

	int indexVal = currentSize-1;



	while (1){

		if(j%2==0){ // Every 2 loops
			t = Xil_In32(GLOBAL_TMR_BASEADDR + GTIMER_COUNTER_LOWER_OFFSET) - time_now;
		}

		int newSample[] = {(int) I2SFifoRead(AUDIO_FIFO), (int) I2SFifoRead(AUDIO_FIFO)};

		bufferL[indexVal] = newSample[0];
		bufferR[indexVal] = newSample[1];

		toReturn[0] = 0;
		toReturn[1] = 0;

		time_now = Xil_In32(GLOBAL_TMR_BASEADDR + GTIMER_COUNTER_LOWER_OFFSET);

		filter();

		time_func = Xil_In32(GLOBAL_TMR_BASEADDR + GTIMER_COUNTER_LOWER_OFFSET) - time_now;


		if(j%100000 == 0){ // Every 2-3 seconds
			xil_printf("Filter : %d, Loop : %d\n",time_func, t);
			j = 0;
		}


		I2SFifoWrite(AUDIO_FIFO, toReturn[0]);
		I2SFifoWrite(AUDIO_FIFO, toReturn[1]);

		j++;
    
    // Updating indexVal
		indexVal = indexVal == 0 ? currentSize-1 : (indexVal-1)%currentSize;
	}

	cleanup_platform();
	return 0;
}