Unfortunately, such a tool that is known to work in all cases is unknown to us; if you see one, hear about one, or write one yourself, be sure to tell us. Here's one person's try. In the meantime, here is what you can do to convert your code:

• For a small number of relatively short files, consider converting them with a smart editor (like emacs or its work-alikes).

• Obtain a copy of Microsoft MASM 6.11. It has -coff option to generate object code in COFF format which can be submitted to gcc, so you can compile your original source. You can also use lib32 librarian from Microsoft C8 to convert object files to COFF by putting them into a .lib library, then extracting them as COFF files.