Configure metadata/cache for a .vcd or .vcd.gz waveform. Large files are metadata-only; use build_index for expensive indexing.

Check cache/index readiness without rebuilding and without fully parsing the VCD.

Explicitly build expensive indexes. Levels: changes, runs, edges, full.

Return loaded waveform metadata including timescale, signal count, change count, and time range.

Find candidate VCD signals by exact, leaf, substring, or token match. Use before querying ambiguous names.

Return one signal's exact held value at a time. Time may be a raw tick or unit string like 25ns.

Batch value_at for multiple signals at one time. Prefer this over repeated value_at calls.

Return changes for one signal in an inclusive time window.

Batch changes for multiple signals in one time window. Prefer this for waveform debug context.

Return precomputed signal edges. Kinds include rise, fall, x_enter, x_exit, z_enter, z_exit, scalar_change, vector_change.

Return the first edge of a given kind after a time.

Check whether a signal changed between two times.

Summarize what changed around a time without dumping raw VCD text. Good first debug query near a failure.

Build a cycle index from one signal's edge events. Call before cycle-based tools.

Map a time to the latest clock cycle at or before that time.

Map a clock cycle index to its VCD time.

Batch values_at for several signals at a clock cycle.

Return one signal's changes between two clock cycle indices.