sine.c.txt

This program produces a Frequency Domain display from the Time Domain * data input using the Fast

/* 
 *  sine.c 
 * 
 *  Unix Version 2.4 by Steve Sampson, Public Domain, September 1988 
 * 
 *  This program is used to generate time domain sinewave data 
 *  for fft.c.  If you want an opening target - negate the 
 *  test frequency. 
 */  
  
#include <STDIO.H>   
#include <MALLOC.H>   
#include <MATH.H>   
  
#define TWO_PI  (2.0 * 3.14159265358979324)   
#define Chunk   (Samples * sizeof(double))   
  
static double   Sample, Freq, Time, *Real, *Imag;  
static int  Samples;  
static void err_report();  
static FILE *Fp;  
  
  
main(argc, argv)  
int argc;  
char    **argv;  
{  
    register int    loop;  
  
    if (argc != 3)  
        err_report(0);  
  
    Samples = abs(atoi(*++argv));  
  
    if ((Real = (double *)malloc(Chunk)) == NULL)  
        err_report(1);  
  
    if ((Imag = (double *)malloc(Chunk)) == NULL)  
        err_report(2);  
  
    printf("Input The Test Frequency (Hz) ? ");  
    scanf("%lf", &Freq);  
    printf("Input The Sampling Frequency (Hz) ? ");  
    scanf("%lf", &Sample);  
    Sample = 1.0 / Sample;  
  
    Time = 0.0;  
    for (loop = 0; loop < Samples; loop++)  {  
        Real[loop] =  sin(TWO_PI * Freq * Time);  
        Imag[loop] = -cos(TWO_PI * Freq * Time);  
        Time += Sample;  
    }  
  
    if ((Fp = fopen(*++argv, "w")) == NULL)  
        err_report(3);  
  
    fwrite(Real, sizeof(double), Samples, Fp);  
    fwrite(Imag, sizeof(double), Samples, Fp);  
    fclose(Fp);  
  
    putchar('\n');  
  
    free((char *)Real);  
    free((char *)Imag);  
  
    exit(0);  
}  
  
  
static void err_report(n)  
int n;  
{  
    switch (n)  {  
    case 0:  
        fprintf(stderr,"Usage: sine samples output_file\n");  
        fprintf(stderr,"Where samples is a power of two\n");  
        break;  
    case 1:  
        fprintf(stderr,"sine: Out of memory getting real space\n");  
        break;  
    case 2:  
        fprintf(stderr,"sine: Out of memory getting imag space\n");  
        free((char *)Real);  
        break;  
    case 3:  
        fprintf(stderr,"sine: Unable to create write file\n");  
    }  
  
    exit(1);  
}  
  
/* EOF */