/*****************************************************************
*  ale_floatpt.c - Floating-point C program of ALE	             
******************************************************************
*  System configuration:
*
* d(n) ---------------------------
*     |             /             |
* d(n-1)|----------------| out(n) V
*  ---->| ALE (LMS-FIR)  |-----> |+|-----> e(n)
*       |----------------|     -      | 
*             /_______________________|
*
******************************************************************
*  System simulation configuration:
*
*     d(n) is the input data from data file "in.dat"
*     out(n) is the output data to data file "out.dat"
*
*****************************************************************/

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

void main()
{
/*****************************************************************
*    Define variable arrays, define and clear variables
*****************************************************************/

  #define NL 16		     /* number of FIR filter's tap      */
  float yn = 0.0;            /* y(n), output from the filter    */
  float xn;
  float xnbuf[NL];
  float w[NL];
  int i,j,k;
  float mu = 0.01;
  float mu_err;
  float dn = 0;
  float err;
  
/*****************************************************************
*    Declare file pointers
*****************************************************************/

  FILE *xn_in;                     /* file pointer of x(n)      */
  FILE *yn_out;                    /* file pointer of y(n)      */
  FILE *w_out;
  FILE *err_out;
  xn_in = fopen("in.dat","r");     /* open file for input x(n)  */
  yn_out = fopen("out.dat","w");   /* open file for output y(n) */
  w_out = fopen("w.dat","w");	   /* open file for weight w[0] */
  err_out = fopen("err.dat","w");  /* open file for error       */

  /***************************************************************
  *    Start of main program
  ***************************************************************/
  for(k=0;k<NL;k++)
  {
    xnbuf[k]=0.0;                  /* clear signal buffer       */
    w[k] = 0.0;                    /* clear coefficient buffer  */
  }

  while ((fscanf(xn_in,"%f",&xn)) != EOF)
  {           /* read in x(n) from data file and processing it  */

    for (i=NL-1;i>0;i--)
    {
      xnbuf[i]=xnbuf[i-1];         /* refresh signal buffer     */
    }
    xnbuf[0]=dn;                   /* delayed version of dn     */
    dn = xn;                       /* delayed by 1              */

    /*************************************************************
    *    FIR filtering:
    *         y(n) = sum[x(n-i)*w(i)] for i = 0 to NL-1
    *************************************************************/
    yn = 0.0; 
    for (j=0; j< NL; j++)
    {
      yn += xnbuf[j] * w[j];       /* FIR filtering             */	
    } 
	
    err = dn-yn;                   /* e(n) = d(n) - y(n)        */
    mu_err = mu*err;               /* uen = mu * e(n)           */

    /*    update filter coefficients                            */

    for (k=0; k< NL; k++)
    {
      w[k]=w[k]+mu_err*xnbuf[k];   /* LMS update                */
    }
	
    fprintf(yn_out,"%f\n",yn);     /* save output y(n)          */
    fprintf(err_out,"%f\n",err);   /* save error signal e(n)    */
    fprintf(w_out, "%f\n",w[0]);   /* save trajectory of w[0]   */	
  }
  printf("Finish");		   /* complete filtering        */  
  fcloseall();                     /* close all opened files    */
}