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

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

'stns.idx' contains 177 4-byte integers. Each integer is the number of the record at which each broadcaster's frequencies start within 'stns.dat'.
The first 4-byte integer is the number of broadcasters, thus the index num-
bers of the broadcasters run fron 1 to 176. 'stns.dat' contains all the fre-
quencies of all the broadcasters in one continuous stream of integers. */

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

char FN[28] = "../hfbrx_freqs/freqs000.txt";
char S[8];

/* CONVERT AN 'int x' TO AN l-DIGIT NUMERIC STRING WITH LEADING SPACES OR
   ZEROS IN ARRAY S2[]). */

void showInt(int x, int l, int y) {
  char s = ' ';               // for leading spaces
  if(y) s = '0';              // for leading zeros
  if(l > 11) l = 11;          // safety precaution
  for(int i = 0; i < l; i++)
    S[i] = s;                // fill the whole field with spaces or zeros
  S[l - 1] = '0';
  S[l] = (char)0;            // terminating NULL character
  if(x > 0) {                 // if the number is non-zero:
    int i = l;                // total of 'l' possible digits in the number

    /* While there're still more digits to process, work backwards from [8]
    to [0], storing the remainder after dividing the number by 10 as a numeric
    character in array S[]. Then divide the number by 10 [unrounded] and loop
    back. */

    while(x > 0 && i > 0) {
      S[--i] = (char)(x % 10 + 48);
      x /= 10;
    }
  }
}

int getNum(FILE *F) {
  int x = 0, c;
  char S[8];
  while(!feof(F) && (c = fgetc(F)) != '\n')
    S[x++] = c;
  S[x] = '\0';
  return atoi(S);             // number of frequencies in this file
}

void putInt(int x, FILE *F) {  // SAVE AN INT TO FILE AS 4-BYTE TRAIN
  fputc((x >> 24) & 0xFF, F);  // Store the new number of records
  fputc((x >> 16) & 0xFF, F);  // as a 4 byte int in the first
  fputc((x >>  8) & 0xFF, F);  // 4 bytes of the records file.
  fputc(x & 0xFF, F);
}



void main() {
  FILE *FI = fopen("stns.idx","wb");  // open for writing
  FILE *FF = fopen("stns.dat","wb");  // open for writing
  int Q = 0;
  int N = 176;                  // number of broadcasters
  putInt(N,FI);                 // store the total number of broadcasters
  putInt(N,FI);                 // twice to make an 8-byte record
  int R = 0;                    // 'stns.dat' record number
  for(int K = 0; K < N; K++) {  // for each broadcaster:
    showInt(K,3,1);             // Insert sequence number [000 to 175] of 
    for(int k = 0; k < 3; k++)  // current freqs file as a 3-digit string
      FN[k + 20] = S[k];        // with leading zeros into file name string
    FILE *FT = fopen(FN,"rb");  // and open the input file for reading.
    int I = getNum(FT);         // number of freqs for this broadcaster
    if(I > Q) Q = I;
    if(I > 200) {
      printf("Input File error: K=%i I=%i\n",K,I);
      break;
    }
    putInt(R,FI);  // start record in stns.dat' for this broadcaster's freqs
    putInt(I,FI);  // number of frequencies for this broadcaster
    R += I;        // start record for next broadcaster

    for(int i = 0; i < I; i++) { // for each freq for this broadcaster
      int F = getNum(FT);
      putInt(F,FF);    // copy it into 'stns.dat'
    }
    fclose(FT);  // close the input file
  }
  fclose(FF);    // close 'stns.dat'
  fclose(FI);    // close 'stns.idx'
  printf("Max=%i\n",Q);
}