magic/toolchains/emscripten

Magic VLSI — Headless WASM Build

This toolchain builds Magic as a headless WebAssembly module using Emscripten. X11, Tk, OpenGL, and readline are all disabled. The resulting magic.js / magic.wasm pair can be loaded in Node.js, a browser, or a Web Worker.

Quick start (npm package)

The easiest way to build and use the WASM module is through the npm package:

# Build magic.js + magic.wasm and copy them into npm/
bash npm/build.sh

# Run the test suite (extract, GDS, DRC, CIF)
npm --prefix npm test

See npm/examples/ for usage examples.

Manual build

Prerequisites: an activated emsdk checkout (emcc, emar, emranlib on PATH), plus standard make and gcc.

# 1. Configure for Emscripten
CFLAGS="--std=c17 -D_DEFAULT_SOURCE=1 -DEMSCRIPTEN=1 -g" \
  emconfigure ./configure \
    --without-cairo --without-opengl --without-x --without-tk --without-tcl \
    --disable-readline --disable-compression \
    --host=asmjs-unknown-emscripten \
    --target=asmjs-unknown-emscripten

# 2. Append the Emscripten-specific make settings
cat toolchains/emscripten/defs.mak >> defs.mak

# 3. Build
emmake make depend
emmake make -j$(nproc) modules libs
emmake make techs
emmake make mains

The outputs are magic/magic.js and magic/magic.wasm.

Embedded files

The following runtime files are baked directly into the WASM binary via Emscripten's --embed-file mechanism and are available at startup without any host filesystem access:

Host path	VFS path
scmos/	/magic/sys/current/
windows/windows7.glyphs	/magic/sys/windows7.glyphs
windows/windows7.glyphs	/magic/sys/bw.glyphs

To embed a custom technology file, add an --embed-file entry to TOP_EXTRA_LIBS in defs.mak.

Exported C API

The WASM module exports four functions:

Function	Description
magic_wasm_init()	Initialize Magic (idempotent — safe to call multiple times). Returns 0 on success.
magic_wasm_run_command(const char *cmd)	Dispatch one Magic command. Calls magic_wasm_init() automatically if needed. Returns 0 on success.
magic_wasm_source_file(const char *path)	Read and execute a command file from the virtual filesystem.
magic_wasm_update()	Drive a display-update cycle. No-op in headless builds (null display suspends all redraws).

JavaScript usage

import createMagic from 'magic-vlsi-wasm';

const { runCommand, FS } = await createMagic();

// Write a layout file into the virtual filesystem
FS.writeFile('/work/inv.mag', layoutBytes);

// Run Magic commands
runCommand('tech load sky130A');
runCommand('load /work/inv');
runCommand('gds write /work/inv');

// Read the result back out
const gdsBytes = FS.readFile('/work/inv.gds');

Notes

• CAD_ROOT is automatically set to / so that embedded system files are resolved under /magic/sys/.
• The null display driver (-d null) sets GrDisplayStatus = DISPLAY_SUSPEND, which causes WindUpdate to return immediately without invoking any display callbacks. This is what makes the WASM build safe to run without a screen.
• All POSIX signal/timer APIs (setitimer, SIGALRM, fcntl) are compiled out under __EMSCRIPTEN__; the display progress timer becomes a no-op.