WaveCrux — Waveform Analysis for RTL

The waveform is not the hard part. Working out what the waveform means is.

WaveCrux puts a full debug-analysis layer in a VSCode tab: nine protocol decoders with a transaction table, X-trace to find where an unknown came from, waveform diff across two runs, FSM state views, and switching-activity analysis. Then it connects that tab to the rest of your toolchain — including the tools that are not running inside your editor.

Open a .vcd, .fst, .ghw, .lxt or .lxt2 and it opens here, in an editor tab, beside the RTL that produced it.

Registries: Marketplace · Open VSX (Cursor, Windsurf, VSCodium, Theia)
Licence: Apache-2.0 · Home: wavecrux.app

The analysis layer

Everything below ships in the extension. No account, no key, no separate download — it is the WaveCrux open-core build, embedded.


Protocol decoders	Nine, decoding into a transaction table rather than a squashed bus row: SPI, I²C, UART, AXI4-Lite, APB, AHB-Lite, Wishbone, SPI-Flash (stacked on SPI), and a RISC-V instruction-trace decoder.
X-trace	Walk an `x` backwards to the driver that produced it, instead of scrolling until you spot the transition.
Waveform diff	Two runs side by side, with the divergence found for you. "It passed yesterday" becomes a timestamp.
FSM state visualization	State encodings rendered as states, and the transition you did not expect made visible.
Switching activity	Which nets are actually toggling, and how much — the input to a power conversation, or to finding a runaway clock.
Multi-signal pattern search	Search for a condition across several signals, not one value on one signal.
cocotb log correlation	Line up a cocotb run's log against the trace it produced.
GTKWave `.gtkw` import	Bring your existing saved sessions across. Signal order, groups, and radices survive the move.

Rendering, navigation, formatting and netlist search are table stakes and are built on wellen compiled to WebAssembly — the same parsing engine several other open-source viewers use. We are not claiming to draw a nicer square wave. The claim is everything above.

Built for the editor, not merely hosted in it

Real editor integration. A CustomReadonlyEditorProvider, so waveforms are tabs: they split, they go to a second editor group, they restore with the window, and workbench.editorAssociations works on them.
Live theme bridge. The viewer follows your VSCode theme — light, dark and high-contrast — with a WCAG contrast floor enforced on signal colours, so a high-contrast theme does not produce an unreadable trace.
Large files stream. Bytes reach the viewer in 4 MiB chunks rather than as one allocation, with a 256 MiB ceiling. Cold start measured at 246–406 ms.
RTL value annotation — the feature that is better here than on the desktop. Turn it on and signal values from the waveform render as inline decorations in your own Verilog/VHDL, following the waveform cursor. The desktop app needs a second pane for this; in an editor, your source is already open at the line you are reading. Only stems-exact name matches are annotated and an ambiguous name is shown as ambiguous rather than guessed. Off until you opt in (edacrux.rtlAnnotation.enabled).

Connected to tools that are not in your editor

WaveCrux, LintCrux, SimCrux and NetCrux speak CXP, a cross-process peer protocol. That is the part an in-editor extension API cannot do: CXP reaches the desktop applications, on the same machine, over loopback — so a running NetCrux or LintCrux desktop session is a peer of this window.

Your VSCode window is one CXP peer no matter how many of the four extensions you install: one identity, one manifest, one heartbeat, capabilities composed from whatever is installed. A peer that asks this window to open a source location gets the file opened at the right line.

Install the EDACrux Suite pack to get all four at once.

Getting started

Open any .vcd, .fst, .ghw, .lxt or .lxt2 file in the explorer.
It opens in a WaveCrux tab. Add signals from the hierarchy and navigate.
Optional: run EDACrux: Toggle RTL Value Annotation with a Verilog or VHDL file open to see cursor values inline in your source.

Settings

Setting	Default	What it does
`edacrux.rtlAnnotation.enabled`	`false`	Inline signal values in Verilog/VHDL source, following the waveform cursor
`edacrux.crossProbe.revealSelection`	`true`	Bring the matching tab forward when a connected Crux app announces a selection
`edacrux.crossProbe.openSourceFocusesEditor`	`true`	Move the cursor into the editor when a peer asks to open a source location
`edacrux.crossProbe.followWaveformSelection`	`false`	Reveal a signal's RTL declaration in the editor when you select it in a waveform tab in this window

Commands

Command	Id
Open Waveform Panel	`wavecrux.openPanel`
Toggle RTL Value Annotation	`edacrux.toggleRtlAnnotation`
Send Selection to Crux App	`edacrux.sendSelectionToPeer`
Highlight Selection in Crux App	`edacrux.highlightSelectionInPeer`
Open Capabilities Panel	`edacrux.openCapabilitiesPanel`

Send and Highlight take the identifier under your cursor to a running Crux app: one connected app is sent to directly, several are offered in a quick pick.

What this extension does not do — stated plainly

FSDB is refused, with an explanation. .fsdb requires Synopsys libraries that cannot be redistributed. The extension tells you that instead of failing obscurely.
NetCrux → waveform highlight is not wired yet. WaveCrux's surface advertises no highlight capability rather than accepting the request and dropping it. When the webview command lands, the capability is advertised in the same change.
Restricted workspaces. This extension declares no untrusted-workspace support, so it stays inert until you trust the folder.
Pro and Enterprise features are not bundled. No AI debug advisor, no SV assertion visualization, no collaborative viewing, no Stage Pro custom widget SDK. Those live in WaveCrux Desktop and are linked, never quietly disabled here.
The desktop app is still the deeper tool for multi-tab workspaces, the Stage instrument panel, interactive VCD over a pipe, and the WCP remote control API.

Telemetry

Off unless you have VSCode telemetry on. The extension checks vscode.env.isTelemetryEnabled at send time, not once at startup, so turning telemetry off in VSCode turns it off here immediately.

Localization

English, 简体中文, 日本語 and 한국어 — hand-translated, commands and settings included.

The rest of the suite

Extension	What it is for
LintCrux	RTL lint results as Problems-panel diagnostics, with waivers filed from a quick fix
SimCrux	RTL regressions in the Test Explorer; a failing proof's counterexample opens in a waveform tab beside it
NetCrux	"What drives this signal?" on a selection, resolved through the stems index
EDACrux Suite	All four, installed together

Built by Ferrite Engineering. Apache-2.0. edacrux.app