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

	File:        fir_asm.c (main code)

		     firasm.asm (is called to perform the fir)

	Description: Perform 128-tap fir filtering on codec input.

		     Input: Right channel of line-in

		     Output: Right channel = original signal

			     Left channel  = filtered signal

		     * Note: filter routine is optimized an linked separately.

	

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



#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 44100



extern int inicodec (int sampling_rate);

extern far void fir_asm_init (void);

extern interrupt void fir_asm_intr();



#pragma DATA_ALIGN(h,256)     // Circular buffer of 128 short (2 bytes).

#pragma DATA_ALIGN(R_in,256)  // Circular buffer of 128 short (2 bytes).

short R_in[128];              // Input samples R_in[0] most recent, R_in[127] oldest.

short h[]=                    // Impulse response of FIR filter.

{

	   -2,    10,    14,     7,    -7,   -17,   -13 ,    3,

     19,    21,     4,   -21,   -32,   -16,    18 ,   43,

	   34,    -8,   -51,   -56,   -11,    53,    81 ,   41,

		-44,  -104,   -81,    19,   119,   129,    24 , -119,

   -178,   -88,    95,   222,   171,   -41,  -248 , -266,

		-50,   244,   366,   181,  -195,  -457,  -353 ,   85,

		522,   568,   109,  -540,  -831,  -424,   474 , 1163,

		953,  -245, -1661, -2042,  -463,  2940,  6859 , 9469,

	 9469,  6859,  2940,  -463, -2042, -1661,  -245 ,  953,

	 1163,   474,  -424,  -831,  -540,   109,   568 ,  522,

	   85,  -353,  -457,  -195,   181,   366,   244 ,  -50,

   -266,  -248,   -41,   171,   222,    95,   -88 , -178,

   -119,    24,   129,   119,    19,   -81,  -104 ,  -44,

     41,    81,    53,   -11,   -56,   -51,    -8 ,   34,

     43,    18,   -16,   -32,   -21,     4,    21 ,   19,

	    3,   -13,   -17,    -7,     7,    14,    10 ,   -2

};



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 (fir_asm_intr,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.



	fir_asm_init();

	

	INTR_GLOBAL_ENABLE();              // Enable global interrupt.



	/**************************************************

		Note: In this case, main loop must be empty,

		      Because the interrupt service routine

					uses some registers to implement circular

					buffers. Adding codes may damage the buffer.

	****************************************************/

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

}