/* zipbar.c for surf-mail */
/* by Marshall Plann      */
/* compiled fine in TC++  */
/* 12/91                  */

#include <stdio.h>
#include <string.h>
#include <fcntl.h>
#include <ctype.h>

#define PRINTER_PORT  "lpt1"
#define ESC      27
#define LONG     255
#define SHORT    7
#define SPACE    0
#define K1       7              /* width of a space */
#define K2       4              /* width of a bar */

void write_bars();
void bar_code();
int code_digit();

unsigned char digit_bits[] = { 24, 3, 5, 6, 9, 10, 12, 17, 18, 20 };

main(argc, argv)
int argc;
char *argv[];
{
  int printer;                  /* file to write to */
  char string[256];

  /* first parameter is the zip code or else exit */
  if (argc < 2) {
    printf("Usage: %s zipcode\n" argv[0]);
    exit(-1);
  }

  /* open the printer port */
  if ((printer = open(PRINTER_PORT, O_WRONLY)) == -1) {
    printf("Error opening %s\n", PRINTER_PORT);
    exit(1);
  }

  strcpy(string, argv[1]);

  bar_code(printer, string);    /* print the bar code */
  write(printer, "\n", 1);      /* print a new line */

  close(printer);
  return 0;
}

void bar_code(printer, str)
int printer;
char str[];
{

  char out_str[256];
  int i;
  int digit;
  int count = 0;
  int sum = 0;
  int len = strlen(str);
/* add leading bar */
  count += code_end(&(out_str[count]));
  /* go through the string and  create codes for digits */
  for (i = 0; i < len; i++) {
    if (isdigit(str[i])) {      /* character is a digit */
      digit = str[i] - '0';
      sum += digit;             /* accumulate for checksum */
      if (count > 128) {        /* dump every 128 bytes or so to the printer */
        out_str[count++] = '\0';
        write_bars(printer, out_str, count);
        count = 0;
      }                         /* end if */
      /* code the next digit */

      count += code_digit(digit, &(out_str[count]));
    }                           /* end if */
  }                             /* end for */

  /* generate the checksum     */
  if (sum > 0) {
    count += code_digit((10 - (sum % 10)) % 10, &(out_str[count]));
  }
  /* add trailing bar */
  count += code_end(&(out_str[count]));
  out_str[count++] = '\0';
  write_bars(printer, out_str, count);
}

void write_bars(printer, str, count)
int printer;
char str[];
int count;
{
  char out_str[64];
  int num = 0;
  out_str[num++] = ESC;
  out_str[num++] = '2';
  out_str[num++] = count;
  out_str[num++] = 0;
  out_str[num] = '\0';
  write(printer, out_str, num); /* prepare printer for data */
  write(printer, str, count);   /* write data to printer    */
}

int code_digit(digit, str)
int digit;
char str[];
{
  int i, j, k;
  for (i = 4, k = 0; i >= 0; i--) {

/* use digit_bits as a template
for the bar codes.
If a bit is on then add a long bar.
add a short bar otherwise.
*/

    if ((digit_bits[digit] >> i) & 1) {
      for (j = 0; j < K2; str[k++] = LONG, j++);
    } else {
      for (j = 0; j < K2; str[k++] = SHORT, j++);
    }
    for (j = 0; j < K1; str[k++] = SPACE, j++);
  }
  return k;                     /* number of bytes added */
}

/* adds beginning or trailing bar */
int code_end(str)
char str[];
{
  int j, k = 0;
  for (j = 0; j < K2; str[k++] = LONG, j++);
  for (j = 0; j < K1; str[k++] = SPACE, j++);
  return k;                     /* number of bytes added */
}