/*
 * Program: Global Communicator II - scanner signals converter
 * Programmer: Robert John Morton UK-YE572246C
 * Date:  Tue 22 Sep 2020

From the directory in which 12.c resides: 
to compile: gcc 12.c -o 12

File  Metre Band       Range  File Size
  |    |  Bounds[kHz]    |       |                         Plot
ham00 160  1800- 1900  100kHz  100bytes  1.0 kHz/byte  1                 0*
ham01  80  3400- 3900  500kHz 1000bytes  0.5 kHz/byte  skip every other  1  255
ham02  40  7000- 7100  100kHz  100bytes  1.0 kHz/byte  1                 2*
ham03  30 10100-10200  100kHz  100bytes  1.0 kHz/byte  1                 3*
ham04  20 13950-14450  500kHz 1000bytes  0.5 kHz/byte  skip every other  4  0/255
ham05  17 18000-18200  200kHz  100bytes  2.0 kHz/byte  double plot       5*
ham06  15 20950-21450  500kHz 1000bytes  0.5 kHz/byte  skip every other  6
ham07  12 24800-25000  200kHz  100bytes  2.0 kHz/byte  double plot       7*
ham08  10 28000-30000 2000kHz 1000bytes  0.5 kHz/byte  skip every other  8

SPAN				10MHz	5MHz	2MHz	1MHz	500kHz	200kHz	100kHz
Upper Freq		1023	800	620	572	545		118		92
Centre Freq		 512	512	512	512	512		 64		64
Lower Freq		  12	260	410	442	482		  0		29

*/

#include <stdio.h>   // input output to/from the console and keyboard
#include <stdlib.h>  // standard functions for the 'C' language

void main() {
  FILE *FI = fopen("ham12.dat","rb+");  // open the input file for reading
  FILE *HS = fopen("scope.dat","rb+");  // open the output file for writing

  int f = 24890;                  // start frequency of this band
  int r = f;                      // start byte of this band in scope.dat
  fseek(HS,r,SEEK_SET);           // seek start byte of this band's data
  for(int i = 0; i < 100; i++)    // for each byte of the input file
    fputc('\2',HS);               // save the noise level
  fseek(HS,r,SEEK_SET);           // band start frequency
  for(int i = 0; i < 100; i++) {  // for byte of the input file
    int c = fgetc(FI);            // get next char from input file

    if(c < 2) c = 2;

    if(c == 2) {
      c *= i * (1 - i);
      if(c < 0) c = -c;
      if(c > 12) while(c > 12) c /= 12;
      if(c > 6) c = 12 - c;
      if(c == 0) c = 1;
    } 
    c *= 12;
    fputc(c,HS);     // save the groomed signal level
  }
  fclose(FI);        // close the output file */
  fclose(HS);        // close the output file
}