Open GHW files in your browser
GHDL's own waveform, which keeps VHDL's types: std_logic, enumerations, integers, records and arrays. Open one right here, every signal on one time ruler, with no GTKWave. Nothing leaves your device.
Or drop it anywhere on this page
What you'll see
Your waveform opens with its signals down one side, grouped by scope, and their values along one time ruler.
- Every signal by its scope • Buses in hex, decimal or binary
- Two cursors that snap to edges • The time between them and its frequency
- Find a signal by its name, or a value with =
- Export • PNG, and the values between the cursors as CSV
About GHW
GHDL, the free VHDL simulator, writes GHW when it runs with --wave. Unlike a VCD it keeps what VHDL knows of each signal: its type, a state machine's states by name, integers and physical units, and records and arrays field by field.
A GHW starts with its strings, every type the design uses and the hierarchy of entities, blocks, generates, processes and signals, each signal a list of the scalars its type flattens to. Then comes a snapshot of every scalar's value and, for each moment of the run, the scalars that changed and their new values.
Filepeek reads it in your browser and draws every signal on one time ruler: std_logic as lines, with U, X and - in coral and Z in amber, vectors as buses in hex, decimal or binary, enumerations and integers as their values, reals as curves, and records and arrays as groups of their fields. Delta cycles at one time show their last value. Drag or pinch to move and zoom, put two cursors, find a signal or a value, and save the view as PNG, the values between the cursors as CSV, or the whole waveform as a VCD.
GHDL Waveform
.ghw
Format
- MIME type
- application/x-ghw
- Made by
- GHDL
Inside the file
- Types
- std_logic, enumerations, integers, reals, records, arrays
- Hierarchy
- Entities, blocks, generates and processes
- Snapshot
- Every value at the start
- Cycles
- What changed at each time
Opens in every browser
Filepeek opens GHW files in Chrome, Edge, Firefox and Safari, gzipped or not. On their own, browsers only download them.
- YouChromeOpens through Filepeek
- YouEdgeOpens through Filepeek
- YouFirefoxOpens through Filepeek
- YouSafariOpens through Filepeek
Apps that open GHW
- WindowsGTKWave or Surfer, free
- MacGTKWave or Surfer, free
- iPhone and iPadNo app opens it
- AndroidNo app opens it
Questions
How do I open a GHW file without GTKWave?
Drop it on this page or choose Peek a GHW. Every signal opens on one time ruler in your browser, grouped by its entity, on a phone too.
How do I make GHDL write a GHW?
Run the design with ghdl -r and --wave=name.ghw. GHDL writes every signal of the design into it.
Does it show a state machine's states by name?
Yes. GHW keeps each enumeration's names, so a state signal shows IDLE or RUN rather than a number.
Can I turn a GHW into a VCD?
Yes. Choose Export, then Save as VCD. Bits and vectors go as VCD writes them, reals as reals and enumerations and integers as their values in text.
How do I measure the time between two edges?
Click near the first edge to put cursor A, then shift-click near the second, or choose Measure and click, for cursor B. Each snaps to the nearest change, and the strip shows the time between them and its frequency.