The sample game
A tiny Windows x64 game, written in C for GameFrame, to practise on and to test the tools. It has the parts a real game has: an engine DLL with a random number generator and an allocator, a fixed-step simulation, a constant table, an object with a table of functions (a vtable), and a data file loader.
bash
./build.sh # build/game.exe, build/engine.dll, build/sample.dat (needs zig)
../../.venv/bin/python ground_truth.py # emulate the original: build/truth/seed-N.f32 and .trace
../../.venv/bin/python port.py # the reimplementation: build/port/
../../.venv/bin/python ../../tools/verify/bitcompare.py f32 build/truth/seed-1.f32 build/port/seed-1.f32
../../.venv/bin/python port.py --naive build/naive # doubles instead of floats: watch the checks fail
Try the whole method on it as an exercise: run scripts/ghidra-export.sh on the two binaries, find simulate without looking at game.c, label what you find, read the growth table with tools/pe/readdata.py, and write your own port. The compiler inlined tree_new and the vtable calls into simulate, and the data loader compares its magic as one integer: both are lessons from real games.
| File | What |
|---|---|
engine.c, game.c | The original's source (in a real project you never have this) |
build.sh, make_data.py | Build for Windows x64 from any host with zig cc |
ground_truth.py | Runs simulate under the emulator for 20 seeds, with every random draw traced |
port.py | A reimplementation that matches bit for bit; --naive shows a common mistake |
decode_sample.py | A decoder for the data file, for tools/formats/validate.py |