/*______________________________________________________________________________
MKR2COEF.C		Make Radix-2 FIR Coefficients

This program takes in the direct form FIR coefficients and converts them into
radix-2 FIR coefficients and puts them into a file for R2FIR.ASM.  All data 
will be read and written as floating point.

	USAGE:	mkr2coef <direct coeff src file>  <rad-2 FIR coeff dest. file>
______________________________________________________________________________*/

#include <stdio.h>
#include <math.h>
#define LINELEN    256

main (argc, argv) 
int     argc;
char    *argv[];
{
    FILE    *infile, *outfile;
    char    line[LINELEN];
    double  tmp, x;
    int	    len, i;

    if((argv[1] == NULL) || (argv[2] == NULL)){
        printf("USAGE:	mkr2coef <direct coeff src file> \
 <rad-2 FIR coeff dest. file> \n");
        printf("    This routine converts direct FIR coefficients into  \n");
        printf("    radix-2 FIR coefficients for R2FIR.ASM. \n");
        exit(1);
    }

    if((infile = fopen(argv[1], "r")) == NULL) {
        fprintf(stderr, "Error opening %s\n", argv[1]);
        exit(1);
    }

/* scan for errors, get length of input file */
    len=0;
    while (fgets(line, LINELEN, infile) != NULL) {
        if (sscanf(line, "%lf", &tmp)!=1) {
            fprintf(stderr, "Error: flt pnt number not found:\n", argv[1]);
            fprintf(stderr, "       line=%s\n", line);
            exit(1);
        }
	len++;
    }
    if ((len % 2) != 0 ) {
	fprintf(stderr, "Error: # of taps and filter coeff. must be even!\n");
	exit(1);
    } else if (len == 0) {
	fprintf(stderr, "Error: input file is empty \n");
	exit(1);
    }
    rewind(infile);

/* Open output file */
    if((outfile = fopen(argv[2], "w")) == NULL) {
        fprintf(stderr, "Error opening %s\n", argv[1]);
        exit(1);
    }

/* Write even coeff to output file */
    for (i=0;i<len;i++) {
	fgets(line, LINELEN, infile);
	sscanf(line, "%lf", &x);
	if ((i % 2) == 0)
	    fprintf(outfile,"%14.9e \n",x);
    }	
    rewind(infile);

/* Write odd coeff to output file */
    for (i=0;i<len;i++) {
	fgets(line, LINELEN, infile);
	sscanf(line, "%lf", &x);
	if ((i % 2) != 0)
	    fprintf(outfile,"%14.9e \n",x);
    }	
    rewind(infile);

/* Write even coeff + odd coeff to output file */
    for (i=0;i<len/2;i++) {
	fgets(line, LINELEN, infile);
	sscanf(line, "%lf", &tmp);
	fgets(line, LINELEN, infile);
	sscanf(line, "%lf", &x);
	fprintf(outfile,"%14.9e \n",x+tmp);
    }	

    fclose(infile);	/* We're finished, close all files */
    fclose(outfile);
}