/*______________________________________________________________________
RFFT2TBL.C  Twiddle Factor Generator for ADSP-21020 Radix-2 FFT

Author: 18-FEB-91, Steven Cox, Analog Devices DSP Div. (617) 461-3672
Modified: 3-APR-91, Ronnin Yee, Analog Devices DSP Div. (617) 461-3672
	  12-JUN-91, Ronnin Yee, Analog Devices DSP Div. (617) 461-3672
______________________________________________________________________*/

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

main()
{
  int i, n, iter;
  double freq, c, s;
  double pi;
  FILE *s_file;
  FILE *c_file;
  char filename1[25];
  char filename2[25];

/* initialize pi */
  pi = 4.0*atan(1.0);

  printf("%c%c%c%c",27,91,50,74); /*clear screen*/
  printf("%c%c%c",27,91,72);      /*curser home*/
  printf("________________Radix-2 Real FFT Table Generator____________\n");
  printf("Generates sine and cosine tables for use with the ADSP-21020\n");
  printf("radix-2 real FFT program, RFFT2.ASM.\n");
  printf("12-JUN-91, Ronnin Yee, Analog Devices\n");
  printf("_____________________________________________________________\n");

  printf("Enter the number of points -> ");
  scanf(" %d",&n);
  n=n/2;
  iter=n/2-1;

  printf("\n  Enter the cosine twiddle table filename: ");
  scanf(" %s",filename1);
  c_file=fopen(filename1,"w");

  printf("  Enter the sine twiddle table filename: ");
  scanf(" %s",filename2);
  s_file=fopen(filename2,"w");

  freq=2.0*pi/(double)n;
  for (i=0; i <= iter; i++)
  {
    s=sin((double)i * freq);
    c=cos((double)i * freq);
    fprintf(s_file,"%22.14e\n",s);
    fprintf(c_file,"%22.14e\n",c);
    printf("%d : %22.14e : %22.14e\r",i,s,c);
  }
  fclose(s_file);
  fclose(c_file);

/* Make 0.5*cos(pi*n/N) and 0.5*sin(pi*n/N) tables */

  printf("\n\n  Enter the half cosine coeff table filename: ");
  scanf(" %s",filename1);
  c_file=fopen(filename1,"w");

  printf("  Enter the half sine coeff table filename: ");
  scanf(" %s",filename2);
  s_file=fopen(filename2,"w");

  freq=pi/(double)n;
  for (i=0; i <= iter; i++)
  {
    s=0.5*sin((double)i * freq);
    c=0.5*cos((double)i * freq);
    fprintf(s_file,"%22.14e\n",s);
    fprintf(c_file,"%22.14e\n",c);
    printf("%d : %22.14e : %22.14e\r",i,s,c);
  }
  fclose(s_file);
  fclose(c_file);


  printf("\nFinished\n");
}