Encoding control characters in a Code128 barcode

Question

Below is what I'm using to create a Code128 barcode. I am trying to figure out how to do some sort of regexp search within the $code to find something like "^009" and replace it with "10000110100" without breaking the rest of the encoding. My goal is to be able to use Code128 control characters within the barcode.

I'm going off of this for the control character encoding: http://en.wikipedia.org/wiki/Code_128

  class Barcode128 {
static private $encoding = array(
          '11011001100', '11001101100', '11001100110', '10010011000',
          '10010001100', '10001001100', '10011001000', '10011000100',
          '10001100100', '11001001000', '11001000100', '11000100100',
          '10110011100', '10011011100', '10011001110', '10111001100',
          '10011101100', '10011100110', '11001110010', '11001011100',
          '11001001110', '11011100100', '11001110100', '11101101110',
          '11101001100', '11100101100', '11100100110', '11101100100',
          '11100110100', '11100110010', '11011011000', '11011000110',
          '11000110110', '10100011000', '10001011000', '10001000110',
          '10110001000', '10001101000', '10001100010', '11010001000',
          '11000101000', '11000100010', '10110111000', '10110001110',
          '10001101110', '10111011000', '10111000110', '10001110110',
          '11101110110', '11010001110', '11000101110', '11011101000',
          '11011100010', '11011101110', '11101011000', '11101000110',
          '11100010110', '11101101000', '11101100010', '11100011010',
          '11101111010', '11001000010', '11110001010', '10100110000',
          '10100001100', '10010110000', '10010000110', '10000101100',
          '10000100110', '10110010000', '10110000100', '10011010000',
          '10011000010', '10000110100', '10000110010', '11000010010',
          '11001010000', '11110111010', '11000010100', '10001111010',
          '10100111100', '10010111100', '10010011110', '10111100100',
          '10011110100', '10011110010', '11110100100', '11110010100',
          '11110010010', '11011011110', '11011110110', '11110110110',
          '10101111000', '10100011110', '10001011110', '10111101000',
          '10111100010', '11110101000', '11110100010', '10111011110',
          '10111101110', '11101011110', '11110101110', '11010000100',
          '11010010000', '11010011100', '11000111010');
static public function getDigit($code){
  $tableB = " !\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~";
  $result = "";
  $sum = 0;
  $isum = 0;
  $i = 0;
  $j = 0;
  $value = 0;

  // check each characters
  $len = strlen($code);
  for($i=0; $i<$len; $i++){
    if (strpos($tableB, $code[$i]) === false) return("");
  }

  // check firsts characters : start with C table only if enought numeric
  $tableCActivated = $len> 1;
  $c = '';
  for($i=0; $i<3 && $i<$len; $i++){
    $tableCActivated &= preg_match('`[0-9]`', $code[$i]);
  }

  $sum = $tableCActivated ? 105 : 104;

  // start : [105] : C table or [104] : B table 
  $result = self::$encoding[ $sum ];

  $i = 0;
  while( $i < $len ){
    if (! $tableCActivated){
      $j = 0;
      // check next character to activate C table if interresting
      while ( ($i + $j < $len) && preg_match('`[0-9]`', $code[$i+$j]) ) $j++;

      // 6 min everywhere or 4 mini at the end
      $tableCActivated = ($j > 5) || (($i + $j - 1 == $len) && ($j > 3));

      if ( $tableCActivated ){
        $result .= self::$encoding[ 99 ]; // C table
        $sum += ++$isum * 99;
      }
      // 2 min for table C so need table B
    } else if ( ($i == $len - 1) || (preg_match('`[^0-9]`', $code[$i])) || (preg_match('`[^0-9]`', $code[$i+1])) ) { //todo : verifier le JS : len - 1!!! XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
      $tableCActivated = false;
      $result .= self::$encoding[ 100 ]; // B table
      $sum += ++$isum * 100;
    }

    if ( $tableCActivated ) {
      $value = intval(substr($code, $i, 2)); // Add two characters (numeric)
      $i += 2;
    } else {
      $value = strpos($tableB, $code[$i]); // Add one character
      $i++;
    }
    $result  .= self::$encoding[ $value ];
    $sum += ++$isum * $value;
  }

  // Add CRC
  $result  .= self::$encoding[ $sum % 103 ];

  // Stop
  $result .= self::$encoding[ 106 ];

  // Termination bar
  $result .= '11';

  return($result);
}
}

Can anyone help me with this? How can I do it?

Answer 1

You might try reviewing the code available here:

http://www.davidscotttufts.com/code/barcode.phps

As he seems to have solved quite nicely the generation of several different kinds of barcodes, including CODE128.