74 lines
2.5 KiB
Markdown
74 lines
2.5 KiB
Markdown
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# WASM Compatibility Layer
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This directory contains WASM-specific implementations that allow KiCad to run in a web browser **without modifying KiCad's source code**.
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## Principle
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Instead of patching KiCad source files, we:
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1. Override include paths to use our headers first
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2. Provide alternative implementations for platform-specific code
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3. Link our libraries instead of system libraries
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## Directory Structure
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```
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wasm/
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├── CMakeLists.txt # Master CMake for compatibility layer
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├── README.md # This file
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├── kiplatform/ # Platform abstraction implementations
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│ ├── CMakeLists.txt
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│ ├── app.cpp # App lifecycle (paths, startup)
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│ ├── drivers.cpp # GPU detection (returns "WebGL")
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│ ├── environment.cpp # Environment variables (localStorage)
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│ ├── io.cpp # File I/O (WASM virtual filesystem)
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│ ├── policy.cpp # Security policy (always permissive)
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│ ├── secrets.cpp # Credential storage (localStorage)
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│ ├── sysinfo.cpp # System information
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│ └── printing.cpp # Print support (browser print())
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├── libcontext/ # Coroutine/fiber implementation
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│ ├── CMakeLists.txt
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│ └── fcontext_wasm.cpp # Emscripten Asyncify fibers
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├── shims/ # Header overrides
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│ └── *.h # Headers that redirect to our impls
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└── config/ # Build configuration
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├── kicad_wasm_config.h # Version and feature config
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└── setup.h # Platform setup
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```
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## How It Works
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### Include Path Override
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When building KiCad for WASM, we add our directories first in the include path:
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```bash
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-I$PROJECT_ROOT/wasm/shims
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-I$PROJECT_ROOT/wasm/kiplatform
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-I$PROJECT_ROOT/stubs/include
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```
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This means when KiCad includes `<kiplatform/app.h>`, it finds our version first.
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### Library Override
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We build `libkiplatform_wasm.a` and link it instead of the native kiplatform:
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```bash
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-L$BUILD_ROOT/wasm -lkiplatform_wasm
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```
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### CMake Integration
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The main KiCad build is configured to find our implementations:
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```cmake
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-DCMAKE_MODULE_PATH="$PROJECT_ROOT/cmake"
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-DKIPLATFORM_LIBRARY="$BUILD_ROOT/wasm/libkiplatform_wasm.a"
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```
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## Adding New Implementations
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1. Create the implementation file in the appropriate directory
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2. Add it to the CMakeLists.txt
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3. Ensure the header interface matches KiCad's expected interface
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4. Test with a minimal build before full integration
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