TCPDFBarcode::barcode_imb PHP Method

    protected function barcode_imb($code)
    {
        $asc_chr = array(4, 0, 2, 6, 3, 5, 1, 9, 8, 7, 1, 2, 0, 6, 4, 8, 2, 9, 5, 3, 0, 1, 3, 7, 4, 6, 8, 9, 2, 0, 5, 1, 9, 4, 3, 8, 6, 7, 1, 2, 4, 3, 9, 5, 7, 8, 3, 0, 2, 1, 4, 0, 9, 1, 7, 0, 2, 4, 6, 3, 7, 1, 9, 5, 8);
        $dsc_chr = array(7, 1, 9, 5, 8, 0, 2, 4, 6, 3, 5, 8, 9, 7, 3, 0, 6, 1, 7, 4, 6, 8, 9, 2, 5, 1, 7, 5, 4, 3, 8, 7, 6, 0, 2, 5, 4, 9, 3, 0, 1, 6, 8, 2, 0, 4, 5, 9, 6, 7, 5, 2, 6, 3, 8, 5, 1, 9, 8, 7, 4, 0, 2, 6, 3);
        $asc_pos = array(3, 0, 8, 11, 1, 12, 8, 11, 10, 6, 4, 12, 2, 7, 9, 6, 7, 9, 2, 8, 4, 0, 12, 7, 10, 9, 0, 7, 10, 5, 7, 9, 6, 8, 2, 12, 1, 4, 2, 0, 1, 5, 4, 6, 12, 1, 0, 9, 4, 7, 5, 10, 2, 6, 9, 11, 2, 12, 6, 7, 5, 11, 0, 3, 2);
        $dsc_pos = array(2, 10, 12, 5, 9, 1, 5, 4, 3, 9, 11, 5, 10, 1, 6, 3, 4, 1, 10, 0, 2, 11, 8, 6, 1, 12, 3, 8, 6, 4, 4, 11, 0, 6, 1, 9, 11, 5, 3, 7, 3, 10, 7, 11, 8, 2, 10, 3, 5, 8, 0, 3, 12, 11, 8, 4, 5, 1, 3, 0, 7, 12, 9, 8, 10);
        $code_arr = explode('-', $code);
        $tracking_number = $code_arr[0];
        if (isset($code_arr[1])) {
            $routing_code = $code_arr[1];
        } else {
            $routing_code = '';
        }
        // Conversion of Routing Code
        switch (strlen($routing_code)) {
            case 0:
                $binary_code = 0;
                break;
            case 5:
                $binary_code = bcadd($routing_code, '1');
                break;
            case 9:
                $binary_code = bcadd($routing_code, '100001');
                break;
            case 11:
                $binary_code = bcadd($routing_code, '1000100001');
                break;
            default:
                return false;
                break;
        }
        $binary_code = bcmul($binary_code, 10);
        $binary_code = bcadd($binary_code, $tracking_number[0]);
        $binary_code = bcmul($binary_code, 5);
        $binary_code = bcadd($binary_code, $tracking_number[1]);
        $binary_code .= substr($tracking_number, 2, 18);
        // convert to hexadecimal
        $binary_code = $this->dec_to_hex($binary_code);
        // pad to get 13 bytes
        $binary_code = str_pad($binary_code, 26, '0', STR_PAD_LEFT);
        // convert string to array of bytes
        $binary_code_arr = chunk_split($binary_code, 2, "\r");
        $binary_code_arr = substr($binary_code_arr, 0, -1);
        $binary_code_arr = explode("\r", $binary_code_arr);
        // calculate frame check sequence
        $fcs = $this->imb_crc11fcs($binary_code_arr);
        // exclude first 2 bits from first byte
        $first_byte = sprintf('%2s', dechex(hexdec($binary_code_arr[0]) << 2 >> 2));
        $binary_code_102bit = $first_byte . substr($binary_code, 2);
        // convert binary data to codewords
        $codewords = array();
        $data = $this->hex_to_dec($binary_code_102bit);
        $codewords[0] = bcmod($data, 636) * 2;
        $data = bcdiv($data, 636);
        for ($i = 1; $i < 9; ++$i) {
            $codewords[$i] = bcmod($data, 1365);
            $data = bcdiv($data, 1365);
        }
        $codewords[9] = $data;
        if ($fcs >> 10 == 1) {
            $codewords[9] += 659;
        }
        // generate lookup tables
        $table2of13 = $this->imb_tables(2, 78);
        $table5of13 = $this->imb_tables(5, 1287);
        // convert codewords to characters
        $characters = array();
        $bitmask = 512;
        foreach ($codewords as $k => $val) {
            if ($val <= 1286) {
                $chrcode = $table5of13[$val];
            } else {
                $chrcode = $table2of13[$val - 1287];
            }
            if (($fcs & $bitmask) > 0) {
                // bitwise invert
                $chrcode = ~$chrcode & 8191;
            }
            $characters[] = $chrcode;
            $bitmask /= 2;
        }
        $characters = array_reverse($characters);
        // build bars
        $k = 0;
        $bararray = array('code' => $code, 'maxw' => 0, 'maxh' => 3, 'bcode' => array());
        for ($i = 0; $i < 65; ++$i) {
            $asc = ($characters[$asc_chr[$i]] & pow(2, $asc_pos[$i])) > 0;
            $dsc = ($characters[$dsc_chr[$i]] & pow(2, $dsc_pos[$i])) > 0;
            if ($asc and $dsc) {
                // full bar (F)
                $p = 0;
                $h = 3;
            } elseif ($asc) {
                // ascender (A)
                $p = 0;
                $h = 2;
            } elseif ($dsc) {
                // descender (D)
                $p = 1;
                $h = 2;
            } else {
                // tracker (T)
                $p = 1;
                $h = 1;
            }
            $bararray['bcode'][$k++] = array('t' => 1, 'w' => 1, 'h' => $h, 'p' => $p);
            $bararray['bcode'][$k++] = array('t' => 0, 'w' => 1, 'h' => 2, 'p' => 0);
            $bararray['maxw'] += 2;
        }
        unset($bararray['bcode'][$k - 1]);
        --$bararray['maxw'];
        return $bararray;
    }