/*----------------------------------------------------------------------

	File:        gtz.c

	Description: Perform goertzel algorithm on 200 samples of codec input.

		     Sends goetzel value periodically to mailbox.

							 Each sample generates an interrupt, after each 200 

							 interrupts, a goertzel value is generated.

	

 -----------------------------------------------------------------------*/



#include <stdio.h>

#include <string.h>

#include <common.h>

#include <codec.h>

#include <mcbspdrv.h>

#include <board.h>

#include <stdlib.h>

#include <timer.h>

#include <intr.h>

#include <regs.h>



#define SAMPLING_RATE 8000



extern int inicodec (int sampling_rate);



#pragma CODE_SECTION (isr_rint0, ".iprog")

interrupt void isr_rint0 (void)

{

	static short delay;

	static short delay_1 = 0;

	static short delay_2 = 0;

	static int N = 0;

	static int Goertzel_Value = 0;





	int prod1, prod2, prod3;

	int R_in;

	short input;

	int output;

	short coef_1 = 0x4A70;  // For detecting 1209 Hz



	R_in = MCBSP0_DRR;



	input = (short) R_in;

	input = input >> 4;   // Scale down input to prevent overflow.



	prod1 = (delay_1*coef_1)>>14;

	delay = input + (short)prod1 - delay_2;

	delay_2 = delay_1;

	delay_1 = delay;

	N++;



	if (N==206)

	{

		prod1 = (delay_1 * delay_1);

		prod2 = (delay_2 * delay_2);

		prod3 = (delay_1 *  coef_1)>>14;

		prod3 = prod3 * delay_2;

		Goertzel_Value = (prod1 + prod2 - prod3) >> 15;

		Goertzel_Value <<= 4;   // Scale up value for sensitivity.

		N = 0;

		delay_1 = delay_2 = 0;

	}

		     

	output = (((short) R_in) * ((short)Goertzel_Value)) >> 15;

	MCBSP0_DXR = (output<<16) | (output & 0x0000ffff);



	return;

}



void Init_Interrupts ()

{

	intr_reset();                     // Reset the interrupt system,

					  // disable all interrupts.

	INTR_CLR_FLAG (CPU_INT15);        // Clear previous interrupt request

	INTR_ENABLE (CPU_INT15);          // Enable cpu interrupt line 15

	intr_map(CPU_INT15,ISN_RINT0);    // Link receive interrupt of serial

					  // port 0 to interrupt line 15.

	intr_hook (isr_rint0,CPU_INT15);  // Assign the interrupt service routine

}



void main(void)

{

	evm_init();                        // Initialise EVM board.

	inicodec (SAMPLING_RATE);          // Initialise codec, adjust sampling rate.

	Init_Interrupts ();                // Initialise interrupts and hook isr.



	INTR_GLOBAL_ENABLE();              // Enable global interrupt.



	for (;;);                          // Main loop, does nothing.

}