101 lines
3.3 KiB
Markdown
101 lines
3.3 KiB
Markdown
# Magic VLSI — Headless WASM Build
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This toolchain builds Magic as a headless WebAssembly module using Emscripten.
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X11, Tk, OpenGL, and readline are all disabled. The resulting `magic.js` /
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`magic.wasm` pair can be loaded in Node.js, a browser, or a Web Worker.
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## Quick start (npm package)
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The easiest way to build and use the WASM module is through the npm package:
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```bash
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# Build magic.js + magic.wasm and copy them into npm/
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bash npm/build.sh
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# Run the test suite (extract, GDS, DRC, CIF)
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npm --prefix npm test
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```
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See [`npm/examples/`](../../npm/examples/) for usage examples.
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## Manual build
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Prerequisites: an activated [emsdk](https://emscripten.org/docs/getting_started/downloads.html)
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checkout (`emcc`, `emar`, `emranlib` on `PATH`), plus standard `make` and `gcc`.
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```bash
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# 1. Configure for Emscripten
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CFLAGS="--std=c17 -D_DEFAULT_SOURCE=1 -DEMSCRIPTEN=1 -g" \
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emconfigure ./configure \
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--without-cairo --without-opengl --without-x --without-tk --without-tcl \
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--disable-readline --disable-compression \
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--host=asmjs-unknown-emscripten \
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--target=asmjs-unknown-emscripten
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# 2. Append the Emscripten-specific make settings
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cat toolchains/emscripten/defs.mak >> defs.mak
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# 3. Build
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emmake make depend
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emmake make -j$(nproc) modules libs
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emmake make techs
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emmake make mains
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```
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The outputs are `magic/magic.js` and `magic/magic.wasm`.
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## Embedded files
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The following runtime files are baked directly into the WASM binary via
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Emscripten's `--embed-file` mechanism and are available at startup without
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any host filesystem access:
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| Host path | VFS path |
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|-----------|----------|
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| `scmos/` | `/magic/sys/current/` |
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| `windows/windows7.glyphs` | `/magic/sys/windows7.glyphs` |
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| `windows/windows7.glyphs` | `/magic/sys/bw.glyphs` |
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To embed a custom technology file, add an `--embed-file` entry to
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`TOP_EXTRA_LIBS` in [`defs.mak`](defs.mak).
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## Exported C API
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The WASM module exports four functions:
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| Function | Description |
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|----------|-------------|
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| `magic_wasm_init()` | Initialize Magic (idempotent — safe to call multiple times). Returns 0 on success. |
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| `magic_wasm_run_command(const char *cmd)` | Dispatch one Magic command. Calls `magic_wasm_init()` automatically if needed. Returns 0 on success. |
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| `magic_wasm_source_file(const char *path)` | Read and execute a command file from the virtual filesystem. |
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| `magic_wasm_update()` | Drive a display-update cycle. No-op in headless builds (null display suspends all redraws). |
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### JavaScript usage
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```js
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import createMagic from 'magic-vlsi-wasm';
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const { runCommand, FS } = await createMagic();
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// Write a layout file into the virtual filesystem
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FS.writeFile('/work/inv.mag', layoutBytes);
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// Run Magic commands
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runCommand('tech load sky130A');
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runCommand('load /work/inv');
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runCommand('gds write /work/inv');
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// Read the result back out
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const gdsBytes = FS.readFile('/work/inv.gds');
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```
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## Notes
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- `CAD_ROOT` is automatically set to `/` so that embedded system files are
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resolved under `/magic/sys/`.
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- The null display driver (`-d null`) sets `GrDisplayStatus = DISPLAY_SUSPEND`,
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which causes `WindUpdate` to return immediately without invoking any display
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callbacks. This is what makes the WASM build safe to run without a screen.
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- All POSIX signal/timer APIs (`setitimer`, `SIGALRM`, `fcntl`) are compiled
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out under `__EMSCRIPTEN__`; the display progress timer becomes a no-op.
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