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NovyWave

Plugins

What Are Plugins

Section titled “What Are Plugins”

NovyWave supports WebAssembly plugins that extend its functionality. Plugins run in a sandboxed environment and communicate with NovyWave through a defined interface, so they cannot interfere with the host application or access resources outside their sandbox.

Built-In Plugins

Section titled “Built-In Plugins”

hello_world

Section titled “hello_world”

A minimal example plugin that logs “Hello World!” on startup. The entire source:

struct HelloWorld;


impl Guest for HelloWorld {
    fn init() {
        host::log_info("Hello World!");
    }


    fn shutdown() {
        host::log_info("hello_world plugin shutting down");
    }
}

Each plugin implements the Guest trait with init and shutdown hooks. The host module provides functions like log_info to communicate back to NovyWave. Plugin log output appears in the terminal where NovyWave was launched (e.g., 🔌 PLUGIN[novywave.hello_world]: Hello World!).

reload_watcher

Section titled “reload_watcher”

This plugin watches all opened waveform files for changes on disk. When a file changes, it triggers an automatic reload with a 250ms debounce to avoid redundant reloads during rapid writes.

This is especially useful during simulation. You can re-run your testbench and see updated waveforms in NovyWave without manually reloading — the viewer refreshes on its own as soon as the output file settles.

files_discovery

Section titled “files_discovery”

This plugin discovers new waveform files matching configurable glob patterns and automatically opens them in NovyWave. It supports gitignore-style patterns and filters by file extension.

By default, the plugin filters for fst and vcd extensions. Add ghw if you work with GHDL waveforms.

Configuration options:

  • patterns — glob patterns to match (e.g., ["test_files/**/*.vcd"])
  • allow_extensions — file extensions to accept (default: ["fst", "vcd"], add "ghw" for GHDL output)
  • debounce_ms — debounce interval in milliseconds (default 200ms, minimum 50ms)

Use this plugin when your build system writes simulation output to a known directory and you want NovyWave to pick up new files automatically.

Plugin Configuration

Section titled “Plugin Configuration”

Plugins are configured in the .novywave configuration file under the [plugins] section:

[plugins]
schema_version = 1


[[plugins.entries]]
id = "novywave.reload_watcher"
enabled = true
artifact_path = "plugins/dist/reload_watcher_plugin.wasm"


[plugins.entries.config]


[[plugins.entries]]
id = "novywave.files_discovery"
enabled = true
artifact_path = "plugins/dist/files_discovery_plugin.wasm"


[plugins.entries.config]
debounce_ms = 200
patterns = ["output/**/*.vcd", "sim_results/**/*.fst"]

Set enabled = false to disable a plugin without removing its configuration. This is handy when you want to temporarily turn off a plugin during a debugging session.

Plugin Lifecycle

Section titled “Plugin Lifecycle”

Each plugin goes through a predictable sequence of stages:

  1. init — called once when the plugin loads. Plugins register watchers, patterns, or other setup logic here.
  2. refresh-opened-files — called when the file list or configuration changes, giving the plugin a chance to update its state.
  3. event handlers — receive notifications as things happen: file changes for watcher plugins, new files for discovery plugins.
  4. shutdown — called before the plugin unloads, allowing cleanup.

Host Capabilities

Section titled “Host Capabilities”

Plugins can interact with NovyWave through these host-provided functions:

  • log-info, log-error — write messages to the NovyWave log.
  • get-opened-files — query the list of currently opened waveform files.
  • register-watched-files, clear-watched-files — watch specific files for changes and stop watching them.
  • reload-waveform-files — trigger a reload of all currently opened waveform files.
  • register-watched-directories, clear-watched-directories — watch directories for new or changed files and stop watching them.
  • open-waveform-files — open new waveform files in NovyWave.
  • get-config-toml — read the plugin’s own configuration from the .novywave file.
Section titled “Related Pages”