Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Writer/Xls/Parser.php
private function cellToPackedRowcol($cell)
    {
        $cell = strtoupper($cell);
        list($row, $col, $row_rel, $col_rel) = $this->cellToRowcol($cell);
        if ($col >= 256) {
            throw new WriterException("Column in: $cell greater than 255");
        }
        if ($row >= 65536) {
            throw new WriterException("Row in: $cell greater than 65536 ");
        }

        // Set the high bits to indicate if row or col are relative.
        $col |= $col_rel << 14;
        $col |= $row_rel << 15;
        $col = pack('v', $col);

        $row = pack('v', $row);

        return [$row, $col];
    }
private function cellToPackedRowcol($cell)
    {
        $cell = strtoupper($cell);
        list($row, $col, $row_rel, $col_rel) = $this->cellToRowcol($cell);
        if ($col >= 256) {
            throw new WriterException("Column in: $cell greater than 255");
        }
        if ($row >= 65536) {
            throw new WriterException("Row in: $cell greater than 65536 ");
        }

        // Set the high bits to indicate if row or col are relative.
        $col |= $col_rel << 14;
        $col |= $row_rel << 15;
        $col = pack('v', $col);

        $row = pack('v', $row);

        return [$row, $col];
    }
pack() row and column into the required 3 or 4 byte format.

@param string $cell The Excel cell reference to be packed

@return array Array containing the row and column in packed() format