A php core script - to repair, restructure it to work in codeigniter framework then make it standalone

Hi. I have an old variant of my website and for some reason the "upload data module" (UDM) which is written in corephp, it gives me some error when uploading .excel files into Mysql database. Now, the new website is a codeigniter framework and i would need the same module UDM to work here as well. After code is restructured, i would need the module to be stand alone, to have all the functions in it and not to call from other files. How you make it standalone is your choice. I will need the UDM to receive .csv files too.