function pdf_find_xref() {
       	fseek ($this->f, -min(filesize($this->filename),1500), SEEK_END);
        $data = fread($this->f, 1500);
        
        $pos = strlen($data) - strpos(strrev($data), strrev('startxref')); 
        $data = substr($data, $pos);
        
        if (!preg_match('/\s*(\d+).*$/s', $data, $matches)) {
	 	// mPDF 4.0
           	$this->success = false;
            $this->errormsg = sprintf("Unable to find pointer to xref table");
		return false;
    	}

    	return (int) $matches[1];
    }