Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Shared/OLERead.php
private function _readData($bl)
    {
        $block = $bl;
        $data = '';

        while ($block != -2) {
            $pos = ($block + 1) * self::BIG_BLOCK_SIZE;
            $data .= substr($this->data, $pos, self::BIG_BLOCK_SIZE);
            $block = self::getInt4d($this->bigBlockChain, $block * 4);
        }

        return $data;
    }
private function _readData($bl)
    {
        $block = $bl;
        $data = '';

        while ($block != -2) {
            $pos = ($block + 1) * self::BIG_BLOCK_SIZE;
            $data .= substr($this->data, $pos, self::BIG_BLOCK_SIZE);
            $block = self::getInt4d($this->bigBlockChain, $block * 4);
        }

        return $data;
    }
Read a standard stream (by joining sectors using information from SAT).

@param int $bl Sector ID where the stream starts

@return string Data for standard stream