#include "stdio.h"
#define BUF_THRESHOLD 9		

int main(void)
{
	
  	volatile int * red_LED_ptr = (int *) 0x01111000;	// red LED address
        volatile int * green_LED_ptr = (int *) 0x01111010;	// green LED address
	volatile int * audio_ptr = (int *) 0x01111050;		// audio port address
		 int * sw_ptr = (int *) 0x01111020;	 	// sw address


	int fifospace, left_data, right_data, mono_data;
	int x[3], y[3];
	int gain,b1,b2;


gain=3300; // 0.05
b2=65259;  // 0.95
b1=-124000; // -1.9	

printf("Starting \n");		

		
	while(1)
	{
	fifospace = *(audio_ptr + 1);	 		        // read the audio port fifospace register

			if ( (fifospace & 0x000000FF) > BUF_THRESHOLD ) // check RARC
			{
				// store data until the the audio-in FIFO is empty 
				while (fifospace & 0x000000FF) 
				{
					left_data = *(audio_ptr + 2); 		
					right_data = *(audio_ptr + 3);

					mono_data = (left_data+right_data)>>2;

					x[2]=x[1];x[1]=x[0];
					x[0]= mono_data;

					y[2]=y[1];y[1]=y[0];
					y[0]=(gain*((x[0]-x[2])>>16))-(b1*(y[1]>>16))-(b2*(y[2]>>16));	
				
					mono_data= y[0];

					*(audio_ptr + 2) = mono_data;
					*(audio_ptr + 3) = mono_data; 	
				
					fifospace = *(audio_ptr + 1);	// read the audio port fifospace register
				
				*(green_LED_ptr) = (fifospace & 0x00FF0000);
				*(red_LED_ptr) = (fifospace & 0x000000FF);

				}
			}
			
	}
}