> For some reason, Reko was not able to decompile this code into a C representation, but it still produced a disassembly, which will work just fine for our purposes.
Perhaps an indication that the code in that segment was hand-written in assembly language rather than C?
Probably just due to the fact that nothing in the standard C language maps to the x86 IN and OUT instructions for reading and writing I/O ports, though MS-DOS-era compilers supplied macros or library functions to use them (inp, inpw, outp, and outpw in Microsoft C, for example).