tiir.c

汇编源代码,IIR滤波器

/****************************************************************************
 Copyright (c) 2000 Analog Devices/Intel. All rights reserved.
 Developed by JD(FRIO), IPDC, Bangalore, INDIA.
 ***************************************************************************
  File Name      : tiir.c
  Module Name    : Test IIR 
  Description    : This module tests the iir function.

***************************************************************************/
// Constants 

#define BUFFER_SIZE     64
#define BASE_NSAMPLES   64
#define DELAY_SIZE      15
#define TEST_ERROR  0x0620



// Includes 

#include "mds_def.h"
#include "filter.h"
#include "tiir.h"

/***************************************************************************
 * Func name   :  tiir

****************************************************************************

  Purpose     :  Test iir() function.
  Description :  Performs the following test on either function:
		 1) Low pass attenuation test (Fourth order)
				 
		 multiple value input test, Order = 4 ((N % 2) = 0)
		 				
*************************************************************************/

extern fract16 out[];
extern fract16 in[];        
extern fract16 delay[];     
extern fract16 c[];

extern void _iir(const fract16 [], fract16 [], int, iir_state_fr16 *);


int             // return - Test status flag 
tiir(void (*_iir)(const fract16 [], fract16 [], int , iir_state_fr16 *))

{
    fract16 energy;
    fract32 acc=0;
	int i, nsamples, nstages;
	int error_flag, error = 0;
	int bitaccuracy=4;
    iir_state_fr16 s;
    	
	error_flag = 0; // Clear status flag 
 
 
    /**************************************************************************
     *  Test : Multiple Value Test (Fourth Order, N % 2 = 0)
     *  Type: Correctness
     *  Description: Coefficients for a fourth order low pass filter generated 
	 *                   using Matlab will be passed to the iir routine. . The entire array is 
	 *                               passed to the routine. The energy of the filtered 
	 *                               output using the iir routine and Matlab are compared.
     ***************************************************************************/
	
	printf("\n Testing property ...\n");

    //{ Initialization for Test : Multiple Value Test, N % 2 = 0} 
     
     c[0] = 0x1EFD;
	 c[1] = 0x2B75;
	 c[2] = 0x1F04;
	 c[3] = 0x2776;
	 c[4] = 0xC6B1;
	 c[5] = 0x62ED;
	 c[6] = 0x26DB;
	 c[7] = 0x62F0;
	 c[8] = 0x6F10;
	 c[9] = 0x0108;


    nsamples = BUFFER_SIZE;
    nstages = 2;
    
	for (i = 0; i < DELAY_SIZE; i++)
	 delay[i] = 0;
    
	iir_init(s, c, delay, nstages);

	// Store the Input samples having a frequency in the pass band 

	for(i=0;i<nsamples;i++)
	   in[i] = INPPASS[i]; 

    // Perform Test by calling iir() or _iir() }
// For stall analysis of 64 inputs, test1 is used and test2a and test 2b are masked	
// For testing purposes test2a and test2b are used and test1 is masked.
// Test2a finds iir biquad filter output for Ni/2 samples and dslay line gets updated.
// Test2b finds iir biquad filter output for the next Ni/2 samples with the delay line
	// previously updated by test2a.	
	_iir(in, out, nsamples, &s);								// Test 1
//	_iir(in, out, nsamples/2, &s);								// Test 2a
//	_iir(&in[nsamples/2], &out[nsamples/2], nsamples/2, &s);	// Test 2b


	// Check the energy of the output 
	acc = 0;
	for(i=0;i < nsamples;i++)
		acc += (out[i] * out[i]);
	
	energy = (acc>> NBITS1); // Store accumlated power
												//in fract16 format  
	error = thresh - energy;
	if(error < 0)
		error = -error;
	
//	bitaccuracy = 4;
		
	if ( error > bitaccuracy )
    {
		error_flag = TEST_ERROR|i;
		printf("\n Test failed \n"); 
		printf("\nExpected Output Energy = %x Computed Output Energy = %x\n", thresh, energy);
		printf("\nBit accuracy = %d\n", bitaccuracy);
		return error_flag;   
	}
	else
		printf("Passed Test (two stage biquad)\n");
    return error_flag;   
   	}

main()
{
 int r;
 r = tiir(_iir);
 if(r) 
 printf("\nfunction failed");
}