Inspect values¶

Use value for snapshots at known times and change for event-aligned tables over a time range.

What was the value at a specific time?¶

Sample related signals together:

$ wavepeek value --waves dump.fst \
    --scope tb.dut.cpu \
    --at 120ns \
    --signals state,pc,instr_valid
@120ns state=4'h3 pc=32'h00001040 instr_valid=1'h1

Several points can be requested in one command:

wavepeek value --waves dump.fst \
  --scope tb.dut.cpu \
  --at 100ns,110ns --at 120ns \
  --signals state --signals pc

Use a static projection when only part of a flat vector matters:

wavepeek value --waves dump.fst --scope tb.dut.cpu \
  --at 120ns --signals 'status[7:4],status[0:0]'

What changed in this time range?¶

Start with a short window and a focused signal list:

$ wavepeek change --waves dump.fst \
    --scope tb.dut.cpu \
    --from 100ns --to 160ns \
    --on '*' --sample-mode native \
    --signals req --signals ack,state --max 20
@110ns req=1'h1 ack=1'h0 state=4'h2
@130ns req=1'h1 ack=1'h1 state=4'h3
@150ns req=1'h0 ack=1'h0 state=4'h0

This uses dump-native timestamps and answers "what changed in the file?" If the result is noisy, narrow the window, replace * with a specific signal or edge, or reduce the signal list.

What did the design see on each clock edge?¶

Use the owning clock as the trigger. Pre-edge sampling is the default for edge-only triggers:

wavepeek change --waves dump.fst \
  --scope tb.dut.cpu \
  --from 100ns --to 200ns \
  --on 'posedge clk iff reset_n' \
  --signals state,req,ack \
  --row-mode sparse --max 20

--row-mode sparse suppresses rows where none of the requested values changed between selected clock edges. Remove it when every selected cycle matters.

What is the clock period?¶

Inspect a few native clock transitions:

$ wavepeek change --waves dump.fst \
    --scope tb.dut.cpu \
    --to 100ns --on '*' --sample-mode native \
    --signals clk --max 6
@10ns clk=1'h1
@15ns clk=1'h0
@20ns clk=1'h1

The example has a 10 ns period: consecutive rising edges are at 10 ns and 20 ns.

When following a change, property, or extract result with value, query the row's sample_time if you want the same sampled values. See Clocks and sampling for the difference between time and sample_time.