History

Darryl L. Miles 752d80ba01 wasm: pin INCOMING_MODULE_JS_API (fixes wasmBinary abort on emsdk 6.x) Emscripten's default INCOMING_MODULE_JS_API list dropped `wasmBinary` (present through ~4.x, gone by 6.0.x). With -sASSERTIONS=1 a caller that sets Module.wasmBinary — as the npm harness and the documented API do — then aborts at instantiation: Aborted(`Module.wasmBinary` was supplied but `wasmBinary` not included in INCOMING_MODULE_JS_API) Set the list explicitly so the build no longer depends on Emscripten's default (which drifts between emsdk versions). Allow the properties that matter for embedding/consuming the .wasm across node/web/worker: print, printErr stdout/stderr callbacks wasmBinary, wasm supply the module as bytes / a compiled Module instantiateWasm, locateFile custom instantiation (streaming/caching/ bundlers) and .wasm URL resolution `arguments` is intentionally omitted: main() is defined but never run (magic is driven through the magic_wasm_* exports), so argv is inert here. Verified on emsdk 6.0.2 and 6.0.3: the wasmBinary abort is gone and the module instantiates (0 INCOMING aborts in the smoke run on either). Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>		2026-07-26 14:54:11 -04:00
..
README.md	Add WASM entry point and Emscripten build wiring	2026-05-11 14:20:47 -04:00
build-tcl-wasm.sh	wasm: force TCL select() notifier (Emscripten has no working epoll)	2026-07-26 14:54:11 -04:00
defs.mak	wasm: pin INCOMING_MODULE_JS_API (fixes wasmBinary abort on emsdk 6.x)	2026-07-26 14:54:11 -04:00
post-build.sh	Add WASM entry point and Emscripten build wiring	2026-05-11 14:20:47 -04:00

README.md

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.