One of the particular issues that I've run into, is that I've divided the code into modules (like a good little boy). The gputils toolchain supports separate compilation, relocatable code, and linking. SWEET! But this is assembly code. I can't instantiate the I2C slave or master code for a particular pair of pins on the '688. There are tight timing loops, so the code must directly reference the correct port and pin (as opposed to variably-defined values).
One of my control boards talks to TWO I2C busses, and can operate as both slave and master on both busses. Since I must directly reference the port/pin, this means that I need separate compilations of the assembly code for each bus. And then I run into the problem: symbol conflict.
My solution is to rewrite symbols within the library modules for each bus instantiation. So the "start" function for the I2C master (I2C_M_start in the library's object file) is rewritten to HOUSE_I2C_M_start and LOCAL_I2C_M_start.
This works out really well, though I just ran into a problem where one library refers to another library. Not only do I need to rewrite the entrypoint symbols, but also the external reference symbols.
All of this rewriting is done with some Python code. The object files are COFF files, so I wrote a minimalist library to work with GPASM's object files (rather than generic COFF files). Using that library, I have a support script to add prefixes like HOUSE_ or LOCAL_.
Here are my support scripts:
As an aside, I find it rather amusing to go back to assembly programming days, yet find myself still enmeshed within libraries, object files, and linkers.
