Value command¶

A useful mental model: value is a rough CLI equivalent of an initial block that waits until each requested --at time and then $displays the selected signals — except it samples an existing dump instead of modifying the simulation.

Use value when you want explicit point snapshots instead of a time range.

It is the fastest way to answer questions like:

what was state at reset release,
what did valid, ready, and data look like on selected cycles,
did two related signals agree at specific timestamps.

In practice, value usually comes after info (to get time units and bounds) and scope or signal (to find the right names).

For exact syntax and flags, run wavepeek help value.

Start with one point snapshot¶

If you already know the canonical signal paths, sample them directly:

$ wavepeek value --waves path/to/dump.vcd --at 10ns --signals top.clk,top.data
@10ns top.clk=1'h1 top.data=8'h0f

Use this when you already have full paths from signal, logs, or earlier queries.

Sample several explicit points¶

Pass a comma-separated list as the single --at argument:

$ wavepeek value --waves path/to/dump.vcd --at 5ns,10ns --scope top --signals clk,data
@5ns clk=1'h1 data=8'h00
@10ns clk=1'h1 data=8'h0f

Rows follow the --at order. Duplicate time points are preserved.

Shorten deep names with `--scope`¶

When several signals live in the same scope, set that scope once and keep --signals relative:

$ wavepeek value --waves path/to/dump.vcd --at 10ns --scope top --signals clk,data
@10ns clk=1'h1 data=8'h0f

This is usually the most convenient form for manual debugging.

Keep short input names but print canonical paths¶

Add --abs when you want scope-relative input but fully qualified output:

$ wavepeek value --waves path/to/dump.vcd --at 10ns --scope top --signals clk,data --abs
@10ns top.clk=1'h1 top.data=8'h0f

Use this when you plan to paste results into notes, bugs, or follow-up commands.

Follow `sample_time` from event-driven commands¶

change, property, and extract JSON rows include both time and sample_time. Use sample_time for follow-up value --at queries when you want to inspect the values that were printed, evaluated, or extracted by that row.

This matters for --sample-mode pre-edge: time remains the trigger edge, while sample_time is the point just before that edge. Querying value --at <time> can show the next-cycle payload instead of the values that made the property row match.

Remember that sampling is state-at-time, not change-at-time¶

value returns the latest known value at or before each --at timestamp. A timestamp does not need to be a transition point:

$ wavepeek value --waves path/to/dump.vcd --at 7ns --scope top --signals clk,data
@7ns clk=1'h1 data=8'h00

Use this for spot checks between edges or between visible value changes.

Use JSON for scripts and agents¶

--json returns a stable machine-readable envelope. The data field is an ordered array of snapshots, matching the row shape used by change:

$ wavepeek value --waves path/to/dump.vcd --at 5ns,10ns --scope top --signals clk,data --json
{"$schema":"https://kleverhq.github.io/wavepeek/schema-output-v2.2.json","command":"value","data":[{"time":"5ns","signals":[{"path":"top.clk","value":"1'h1"},{"path":"top.data","value":"8'h00"}]},{"time":"10ns","signals":[{"path":"top.clk","value":"1'h1"},{"path":"top.data","value":"8'h0f"}]}],"diagnostics":[]}

Use this when another tool needs deterministic parsing instead of human formatting.

Non-obvious behavior¶

--at accepts one time token or a comma-separated list in one argument.
--at order is preserved exactly, including duplicates.
--signals order is preserved exactly, including duplicates.
Without --scope, names in --signals are treated as canonical full paths.
With --scope, names in --signals must stay scope-relative. Do not mix relative names and full paths in one request.
--abs affects only human output. With --json, canonical paths are emitted either way.
--at accepts dump start and dump end; both bounds are inclusive.
Time tokens must be integer plus unit. 10ns is valid; 10 and 1.5ns are errors.
Empty comma entries such as 5ns,,10ns are errors.
If a signal has no sampled value at or before a requested time, the command fails instead of inventing a default.
value does not truncate output and does not use --max; result size is bounded by the number of times and signals you requested.
When a timestamp comes from change or property, use the row's sample_time for follow-up payload inspection. time can be a trigger edge whose sampled values came from an earlier point.
Values are printed as Verilog literals. Non-bit-vector dump encodings are currently rejected by this command.