Cross-Platform C Library Build

If you have access to Windows, Mac OS and Linux, please read on:

I need a publicly available C codebase turned into a ready-to-use library on all three major desktop operating systems: Windows, macOS and Linux. The job is straightforward—grab the source, set up a repeatable GCC/MinGW build and produce clean release artefacts for each platform. The project claims that everything is ready to go.

Deliverables I’m expecting
• The environment you built to compile, as a zip/tarball.
• A shared and, if easy, static library for Windows (.dll/.lib), macOS (.dylib/.a) and Linux (.so/.a)
• The exact build scripts or CMake/Makefiles you used, with comments
• A short README that lists the commands to reproduce the build on each OS, plus how to run the demo test
• Any patch files if you had to tweak the original source (no functional changes, only portability fixes). Ideally there will be none.

Once the tests pass on my side, the contract is complete. Let me know your turnaround time and any clarifications you need.