<?php
class code128 {
    private $code = '';
    private $leafB = NULL, $leafC = NULL;
    public function __construct($text, $mode = 'B')
    {
      if (strlen($text) == 0) return NULL;
      $this->mode = $mode;
      if ($mode == 'B') {
          $this->code = substr($text, 0, 1);
          $text = substr($text, 1);
      }
      else if ($mode == 'C') {
          if (strlen($text) < 2) return NULL;
          if (!is_numeric($text[0])) return NULL;
          if (!is_numeric($text[1])) return NULL;
          $this->code = substr($text, 0, 2);
          $text = substr($text, 2);
      }
      else
          return NULL;
      $this->leafB = new code128($text, 'B');
      $this->leafC = new code128($text, 'C');
    }
    public function draw()
    {
        echo "Code [" . $this->code . "]\n";
        if ($this->leafB != NULL) $this->leafB->draw();
        if ($this->leafC != NULL) $this->leafC->draw();
    }
}
    $n = new code128('s92317lsdfa4324', 'B');
    $n->draw();
?>

public function __construct($text, $mode = 'B')
    {
      $this->mode = $mode;
      if ($mode == 'B') {
          $this->code = substr($text, 0, 1);
          $text = substr($text, 1);
      }
      else if ($mode == 'C') {
          $this->code = substr($text, 0, 2);
          $text = substr($text, 2);
      }
      if(strlen($text)>0) $this->leafB = new code128($text, 'B');
      if(strlen($text)>1)
          if(is_numeric($text[0]) && is_numeric($text[1])) $this->leafC = new code128($text, 'C');
    }

if($mode == 'B') list($this->code, $text) = sscanf($text, '%c%s');
  if($mode == 'C') list($this->code, $text) = sscanf($text, '%2d%s');
  if(strlen($text)>0)
      if(array_key_exists(substr($text, 0, 1), $symCode)) $this->leafB = new code128($text, 'B', $this);
  if(strlen($text)>1)
      if(array_key_exists(substr($text, 0, 2), $symCode)) $this->leafC = new code128($text, 'C', $this);

$symCode = array(
/*  alphabet B  alphabet C */
  ' ' => 0,  '00' => 0,
  '!' => 1,  '01' => 1,
  '"' => 2,  '02' => 2,
  '#' => 3,  '03' => 3,
  '$' => 4,  '04' => 4,
  '%' => 5,  '05' => 5,
  '&' => 6,  '06' => 6,

require 'tables.php';
class code128 {
    private $code = NULL;
    private $text = '';
    private $mode = 'Auto';
    private $len = 1;
    private $leafB = NULL, $leafC = NULL, $parent = NULL, $minCode = NULL;
    public function __construct($text, $mode = 'Auto', $parent = NULL)
    {
      global $symCode;
      $this->parent = $parent;
      $this->text = $text;
      $this->mode = $mode;
      if($parent != NULL) {
          $this->len = $this->parent->len + 1;
          if($this->parent->mode != $mode) $this->len++;
       }
      if($mode == 'B') list($this->code, $text) = sscanf($text, '%c%s');
      if($mode == 'C') list($this->code, $text) = sscanf($text, '%2d%s');
      if(strlen($text)>0)
         if(array_key_exists(substr($text, 0, 1), $symCode)) $this->leafB = new code128($text, 'B', $this);
      if(strlen($text)>1)
         if(array_key_exists(substr($text, 0, 2), $symCode)) $this->leafC = new code128($text, 'C', $this);
      if($this->leafB == NULL && $this->leafC == NULL) $this->minCode = $this;
      else {
         $this->minCode = ($this->leafB != NULL) ? $this->leafB->minCode : $this->leafC->minCode;
         if($this->leafC != NULL)
            if($this->minCode->len > $this->leafC->minCode->len) $this->minCode = $this->leafC->minCode;
      }
      return $this;
     }

private function getCode()
{
    $stack = array();
    $p = $this->minCode;
    while($p != NULL) {
        array_push($stack, $p->code);
        if($p->parent != NULL) {
            if($p->parent->mode == 'Auto') { array_push($stack, 'Start'.$p->mode); break;}
            if($p->mode != $p->parent->mode) array_push($stack, 'Code'.$p->mode);
        }
        $p = $p->parent;
    }
    return $stack;
  }

private function printPattern($code, $posX, $res, $height)
  {
    for($i = 0; $i < strlen($code); $i++) {
        $w = $res*intval($code[$i]);
        if(!($i%2))
            echo "  <rect x='$posX' y='0' width='$w' height='$height' fill='#0'/>\n";
        $posX += $w;
      }
      return $posX;
   }
   public function printSVG($resolution=1, $height=50)
   {
      global $symCode;
      global $barPattern;
      $s = $this->getCode();
      $pos = 1;
      $offset = $resolution*11;
      $width = ((count($s) + 4)*11 + 2)*$resolution;
      echo "<svg xmlns='http://www.w3.org/2000/svg' width='$width' height='$height'>\n";
      $start = $symCode[array_pop($s)];
      $checksum = $start;
      $offset = $this->printPattern($barPattern[$start], $offset, $resolution, $height);
      while(!empty($s)) {
          $code = $symCode[array_pop($s)];
          $offset = $this->printPattern($barPattern[$code], $offset, $resolution, $height);
          $checksum += $code*$pos;
          $pos++;
      }
      $offset = $this->printPattern($barPattern[$checksum%103], $offset, $resolution, $height);
      $offset = $this->printPattern($barPattern[$symCode['Stop']], $offset, $resolution, $height);
      echo "</svg>\n";
    }

$barPattern = array(
  '212222',  /* 0 */
  '222122',  /* 1 */
  '222221',  /* 2 */
  '121223',  /* 3 */
  '121322',  /* 4 */

header('Content-Type: image/svg+xml');
    echo "<?xml version='1.0' encoding='UTF-8' standalone='no'?>\n\n";
    $n = new code128(html_entity_decode($_SERVER["QUERY_STRING"]));
    $n->printSVG();

<img src="barcode128.php?ad32324adsFAE13413ldsFf">