#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>

int main(int argc, char **argv) {

  int fd;
  long count, recv;
  unsigned char *buf,*tmp_uchptr;
  long check = 0;
  unsigned char tmp_uchar;

  if(argc>1)
    count = strtol(argv[1],NULL,10);
  else {
    fprintf(stderr,"Use %s number_of_bits_you_want_to_read\n",argv[0]);
    fprintf(stderr,"    %s %d  # for example, reads 1000 bits\n",argv[0],1000);
    fprintf(stderr,"    usually there's approx. 700 bits read\n");
    fprintf(stderr,"    so a buffer of 1000 is more than enough\n");
    exit(0);
  }
  buf = (unsigned char *) malloc(count*sizeof(unsigned char));

  if(!buf){
    fprintf(stderr,"malloc\n");
    exit(1); 
  }

  fd = open("/dev/paraseat0", O_RDWR);
  if(fd == -1) {
    fprintf(stderr, "Error: could not open /dev/paraseat0 for reading.\n");
    exit(1);
  }

  recv = read(fd,buf,count);
  close(fd);
//  fprintf(stderr,"%lu bits requested; %lu bits read\n",count,recv);
  tmp_uchptr = buf;
  while(check<recv-6){
    // read the 7 bit (ascii-32) values:
    // start sentinel is ascii 69-32
    tmp_uchar = (unsigned char)(        // finding start sentinel 1000101=69
                                        // start sentinel is 0x45=69
                  tmp_uchptr[6] << 6 | 
                  tmp_uchptr[5] << 5 | 
                  tmp_uchptr[4] << 4 | 
                  tmp_uchptr[3] << 3 | 
                  tmp_uchptr[2] << 2 | 
                  tmp_uchptr[1] << 1 | 
                  tmp_uchptr[0]);
    // negate if using parallel port
    // tmp_uchar = ~tmp_uchar;  // comment out this line on ISA version
    //if(tmp_uchar == 0x45){ // isa
    if(tmp_uchar == 69){ // para
      fprintf(stderr,"readcard: start sentinel found at %ld\n",check);
      break;
    }
    check++;
    tmp_uchptr++;
  }
  tmp_uchptr += 7;
  check += 7;
  while(check<recv-6){
    tmp_uchar = (unsigned char) (        // parsing actual data
                  tmp_uchptr[6] << 6 | 
                  tmp_uchptr[5] << 5 | 
                  tmp_uchptr[4] << 4 | 
                  tmp_uchptr[3] << 3 | 
                  tmp_uchptr[2] << 2 | 
                  tmp_uchptr[1] << 1 | 
                  tmp_uchptr[0]); 
    // negate if using parallel port
    // tmp_uchar = ~tmp_uchar;  // comment out this line on ISA version
    if(tmp_uchar == 31){
      fprintf(stderr,"readcard: end sentinel found\n");
      break;
    }
    printf("%c",(63&tmp_uchar)+32);
    check+=7;
    tmp_uchptr+=7;
  }

  printf("\n");
  return 0;
}