Read parallel port data and write it to a file

//////////////////////////////////////////////////////////////////////////////////
//    This file is LEEPAR
//    Creation date is sometime in the 90's by Miguel Angel Rodriguez Jodar
//    (c)2020 Miguel Angel Rodriguez Jodar. ZXProjects
//
//    This program is free software: you can redistribute it and/or modify
//    it under the terms of the GNU General Public License as published by
//    the Free Software Foundation, either version 3 of the License, or
//    (at your option) any later version.
//
//    This program is distributed in the hope that it will be useful,
//    but WITHOUT ANY WARRANTY; without even the implied warranty of
//    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//    GNU General Public License for more details.
//
//    You should have received a copy of the GNU General Public License
//    along with this core.  If not, see <https://www.gnu.org/licenses/>.
//
//    All copies of this file must keep this notice intact.
//
//////////////////////////////////////////////////////////////////////////////////

#include <stdio.h>
#include <stdlib.h>
#include <conio.h>
#include <string.h>
#include <dos.h>
#include <bios.h>

int base;

#define DATOS (base)
#define ESTADO (DATOS+1)
#define CONTROL (DATOS+2)

void main (int argc, char *argv[])
{
  char *buffer;
  FILE *f;
  int fin;
  char dato;
  int *dpuerto;
  unsigned long i=0;

  dpuerto=MK_FP (0x40, 0x8);
  base=*dpuerto;

  if (argc<2)
  {
    printf ("Uso: LEEPAR fichero\n");
    exit(1);
  }

  printf ("Encontrado puerto parlelo en %04.4X\n", base);

  buffer=malloc(512);
  f=fopen (argv[1], "wb");

  fin=0;
  while (!fin)
  {
    outp (CONTROL, 0x22); //autofeed=1, el en otro lado, busy=1
    while ((inp(ESTADO) & 0x40))
    {
      if (kbhit())
        if (getch()==27)
        {
          fin=1;
          break;
        }
    }
    outp (CONTROL, 0x20);
    dato=inp (DATOS);
    fwrite (&dato, 1, 1, f);

    printf ("Leidos %lu bytes        \r", ++i);

    while ((inp(ESTADO) & 0x40)==0)
    {
      if (kbhit())
        if (getch()==27)
        {
          fin=1;
          break;
        }
    }
  }

  fclose(f);
  free(buffer);
}