This is a custom pragma processor meant for use with matching decompilation projects for GameCube and Wii games. It currently adds support for #pragma regswap and #pragma iswap.

If some reconstructed C/C++ source code compiles to object binary whose only differences with a target binary are misassigned registers, you can use #pragma regswap to correct the register assignment. This is an alternative to the strategy of inlining the desired assembly that aims to be more compact, self-documenting, and convenient.

pragma.py will compile your source code, then perform the register and instruction swaps by patching the range of the object file specified in each pragma invocation.

Usage

Invoke #pragma regswap one or more times in a C or C++ source file with the following parameters:

#pragma regswap start end regA regB startFile

where,

start - absolute address of start of affected region in hexadecimal format
end - absolute address of end of affected region (in hex)
regA - register to be swapped with regB (r0-r31 or f0-f31)
regB - register to swapped with regA (r0-r31 or f0-f31)
startFile - absolute address of the first function provided by this file (in hex)

Invoke #pragma iswap with the following parameters:

#pragma iswap addrA addrB startFile

where,

addrA and addrB - absolute addresses of the instructions to be swapped

Then, invoke the pragma processor:

python3 pragma.py [-h] cc cflags output source

Future Work

Support for more architectures besides Gekko/Broadway PowerPC