Theseus: Translating Win32 to WASM

2 days ago

Theseus is a win32/x86 emulator that now generates WebAssembly output, enabling .exe files to run on the web, though it has bugs.
The main challenge in translating to WebAssembly was handling blocking behavior, as WebAssembly on the main thread cannot block; this is resolved using web workers and shared memory with atomics for synchronization.
Design decisions include using synchronous emulation with real OS threads for better debugging and performance, contrasting with an earlier asynchronous approach that had control overhead.
The implementation uses a 'Host' API abstraction for cross-platform compatibility (SDL and web), with TypeScript for the web host due to better tooling and DOM interaction compared to WebAssembly.

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