ccsfir.c

一个MATLAB的应用程序

/*-------------------------------------------------------------------*
 * CCSFIR.C - Target Source code for demo : CCSFIRDEMO
 *   Implements a simple FIR filter that uses signed integers (16-bit)
 *   for both data and coefficients.
 *
 * Unintialized data (must be filled in before execution!)
 *  int16 din[];        - input data of storage (data to be filtered)
 *  int32 nbuf          - number of valid elements stored in din[] (and dout)
 *  int16 coeff[];      - FIR filter coefficients
 *  int32 ncoeff;       - number of valid elements stored in coeff[]
 *------------------------------------------------------------------*/
/* Copyright 2001-2002 The MathWorks, Inc.
 * $Revision: 1.6 $ $Date: 2002/06/12 15:31:04 $ */
 
#include <stdio.h> 
#include <stdlib.h> 
#include "tmwtypes.h"

#ifdef DEBUG
#define  dbg_puts(STR)  puts(STR)
#else
#define  dbg_puts(STR)  
#endif 

void fir_filter(void);
 
enum etype { 
       NO_ERROR = 0,
	   COEFF_OVER,
	   COEFF_UNDER,
	   BUF_OVER,
	   BUF_UNDER,
       UNKNOWN
	};
         
enum etype errorcondition = NO_ERROR;

#define MAX_BUFSIZE    2048   /*-- Upper limit on data buffer --*/
#define MAX_COEFF      64     /*-- Upper limit on number of coeff --*/

/*-- define buffers, leave uninitialized, to be supplied by Matlab -*/

int16 din[MAX_BUFSIZE];
int16 dout[MAX_BUFSIZE];
                        
int16 coeff[MAX_COEFF];
/*-- defines actual size, must be less than limit -*/

int32 ncoeff;
int32 nbuf;

/*----------- main ---------------------------------------------*
 *  This program is used with the Demo for the Code Composer Studio(tm) IDE.
 * 
 *  It uses the DSPLIB supplied by Texas Instruments to filter
 *  blocks of data generated by Matlab.  
 *
 * Note - when main 
 *--------------------------------------------------------------*/
void main()
{ 
  dbg_puts("Start");
  fir_filter();  
  if(errorcondition == NO_ERROR)
  	dbg_puts("Completed FIR filter, NO ERRORS!\n");
  else
    dbg_puts("!!! FIR execution failed\n");
    
  /*exit(0);  This routine must cause the program to halt */
}

/*----------- fir_filter ---------------------------------------*
 *  Implementation of FIR filter
 *  By default, this subroutine uses a "C" implementation
 *  of the FIR filter.  However, it is possible to substitute
 *  the default code for the FIR filter routine 'fir-gen' supplied
 *  in the optimized DSP Library created by Texas Instruments.
 *  
 *--------------------------------------------------------------*/
void fir_filter( )
{ 
  /* This is an alternate version of fir_filter program that 
   *  uses the Texas Instruments library file: dsplib.lib
   *  To use this version, include this library in the project,
   *  then substitute this code for the C version of the filter.
   *  the library version is an optimized Assembly language library
   *  routine that should run much faster
   * fir_gen syntax:
   *  void fir_gen (short *x, short *h, short *r, int nh, int nr)  
   *  x = input array
   *  h = coefficient array
   *  r = output array
   *  nh = number of coefficients (nh >= 5)
   *  nr = number of output samples (nr >= 1) 
   */
   /*
   if (nbuf < 1) { 
     errorcondition = DIN_OVER;
     printf("Illegal buffer size\n");
   }
   if (ncoeff < 5) {
     errorcondition = COEFF_OVER;
     printf("Illegal buffer size\n");
   }
   fir_gen(din,coeff,dout,ncoeff,nbuf); 
  */
 
   int32 i, j, sum;  
   if( ncoeff < 1 ) {
     errorcondition= COEFF_UNDER;
     return;
   }
   else if( ncoeff > MAX_COEFF) {
     errorcondition= COEFF_OVER;
     return;
   }
   else if ( nbuf < 1) {
     errorcondition= BUF_UNDER;
     return;
   }    
   else if ( nbuf > MAX_BUFSIZE) {
     errorcondition= BUF_UNDER;
     return;
   } 

   for (j = 0; j < nbuf; j++) {
   	 sum = 0;
     for (i = 0; i < ncoeff; i++) {
       sum += din[i + j] * coeff[i]; 
       dout[j] = sum >> 15;
     } 
   } 
   errorcondition = NO_ERROR;
   return;                                                               
}