magic/npm

magic-vlsi-wasm

Magic VLSI layout tool, compiled to WebAssembly as a headless library. Runs in Node.js, browsers, and Web Workers — no X11, no Tk, no native dependencies.

Use it to programmatically read and write .mag, .gds, .cif, .ext, and SPICE netlists; run DRC; extract parasitics — anywhere JavaScript runs.

The package ships two variants:

Variant	Entry point	Description
notcl (default)	magic-vlsi-wasm	Standalone — no Tcl interpreter. Commands are plain Magic command strings.
tcl	magic-vlsi-wasm/tcl	Embeds a full Tcl 9 interpreter. Commands are evaluated as Tcl; Magic commands are available as the ::magic:: ensemble.

Install

The package is published to GitHub Packages. Add the following to your project's .npmrc so npm knows where to find it:

@rtimothyedwards:registry=https://npm.pkg.github.com

Then install:

npm install @rtimothyedwards/magic-vlsi-wasm

If the package is private or you hit a 401, authenticate with a GitHub personal access token that has the read:packages scope:

//npm.pkg.github.com/:_authToken=YOUR_TOKEN
@rtimothyedwards:registry=https://npm.pkg.github.com

Requires Node.js 18 or newer.

Quick start

Default variant (no Tcl)

import createMagic from 'magic-vlsi-wasm';

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

// Drop a layout into Magic's virtual filesystem
FS.mkdirTree('/work');
FS.writeFile('/work/inv.mag', layoutBytes);

// Run Magic commands — scmos is built into the WASM binary, no tech file needed
runCommand('tech load scmos');
runCommand('load /work/inv');
runCommand('gds write /work/inv');

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

TCL variant

import createMagic from 'magic-vlsi-wasm/tcl';

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

// Pure Tcl works directly
runCommand('set x 42');
runCommand('puts $tcl_version');

// Magic commands are available as the ::magic:: ensemble
runCommand('magic::tech load scmos');
runCommand('magic::load /work/inv');
runCommand('magic::gds write /work/inv');

The scmos technology family (scmos, minimum, nmos, ...) is embedded in the WASM binary and available out of the box — those names work without writing any tech file. To use a custom technology, write its .tech file into the VFS at /magic/sys/current/<name>.tech before calling tech load <name>.

API

createMagic(options?): Promise<MagicInstance>

options is forwarded to the underlying Emscripten module. Useful keys:

Key	Default	Purpose
wasmBinary	fetched lazily	Pre-fetched ArrayBuffer of magic.wasm (skips a network round-trip in browsers)
print	console.log	Callback for each stdout line
printErr	console.error	Callback for each stderr line

The returned MagicInstance exposes:

Method	Description
runCommand(cmd: string)	Dispatch a single Magic command. Returns 0 on success.
sourceFile(path: string)	Execute a script from the virtual filesystem. Returns 0 on success, -1 if the file could not be opened.
init()	Force initialization. Idempotent — runCommand and sourceFile call it for you.
update()	Drive a display-update cycle. No-op in this headless build.
FS	Emscripten virtual filesystem. See the Emscripten docs.

Full TypeScript types ship in index.d.ts.

Low-level access

createMagic() is a thin convenience wrapper over the underlying Emscripten module. If you need direct access — for example to call cwrap yourself or to drive magic_wasm_init manually — import the module factory directly:

import createMagicModule from 'magic-vlsi-wasm/magic.js';

const module = await createMagicModule({ wasmBinary, print, printErr });
module._magic_wasm_init();
const run = module.cwrap('magic_wasm_run_command', 'number', ['string']);
run('tech load scmos');

The bundled examples use this lower-level path together with a small helper class (examples/helpers.js) that adds a runScript(text) convenience method — it splits a multi-line Tcl block, strips comments, and dispatches each line via runCommand. Useful when you have a script as a string rather than as a file in the VFS.

Examples

The package ships runnable examples for the most common workflows. After installing, run one directly:

node node_modules/magic-vlsi-wasm/examples/extract.js
node node_modules/magic-vlsi-wasm/examples/gds.js
node node_modules/magic-vlsi-wasm/examples/drc.js
node node_modules/magic-vlsi-wasm/examples/cif.js

Or, when developing inside this repo:

npm test           # full suite (extract, gds, drc, cif)
npm run example    # extract.js — RC extraction + SPICE netlist
npm run test:gds   # GDS write only
npm run test:drc   # DRC check only
npm run test:cif   # CIF write only

Each example loads the bundled min.mag (a small NPN transistor cell from Magic's own scmos test suite) under the built-in scmos technology — no external tech file required. See examples/ for the source; example.js is the simplest entry point (GDS → CIF conversion in ~40 lines).

Build from source

If you want to rebuild the WASM module yourself, see toolchains/emscripten/README.md. The short version:

bash npm/build.sh                    # both variants, debug build
bash npm/build.sh --variant=notcl    # default variant only (faster)
bash npm/build.sh --variant=tcl      # TCL variant only
bash npm/build.sh --release          # optimized (-O2, no debug symbols)
bash npm/build.sh --test             # build + run tests
bash npm/build.sh --pack             # build + produce magic-vlsi-wasm-<version>.tgz

You will need an activated emsdk on your PATH. If you pass EMSDK_DIR=/path/to/emsdk, build.sh sources emsdk_env.sh for you.

TCL variant: cloning the TCL source tree

The TCL variant links against a static WASM build of tcltk/tcl, pinned to a specific commit in npm/tcl.ref. build.sh clones the source tree automatically into a ../tcl sibling directory on the first run:

# Override the default clone location
TCL_REPO=/path/to/existing/tcl bash npm/build.sh --variant=tcl

Updating the pinned TCL version

Edit npm/tcl.ref and set TCL_REF to the desired commit SHA or tag, then commit and push. CI will rebuild and republish automatically on the next version tag.

Limitations

• Headless only. There is no display driver, so commands that draw to a window (view, findbox, interactive macros) are no-ops.
• WASM memory starts at 32 MB and grows as needed. Very large GDS imports may need INITIAL_MEMORY bumped (rebuild required).
• Single-threaded. WASM modules are not thread-safe — create one instance per worker.

License

HPND — Copyright (C) 1985, 1990 Regents of the University of California.

Bundled test layout

The example layout examples/min.mag is taken from Magic's own scmos test suite (scmos/examples/bipolar/min.mag) and is included here as a runnable smoke test for the WASM build. The scmos technology it targets is compiled into the WASM binary, so no external tech file is shipped.