Reader¶

Wavekit has three readers: VcdReader for VCD files, FstReader for FST files, and FsdbReader for FSDB files. They use the same clock-sampled loading interface. Use readers as context managers so their resources are released automatically when the block exits:

from wavekit import FsdbReader, FstReader, VcdReader

with VcdReader('simulation.vcd') as reader:
    data = reader.load_waveform('tb.dut.data[7:0]', clock='tb.clk')

with FstReader('simulation.fst') as reader:
    data = reader.load_waveform('tb.dut.data[7:0]', clock='tb.clk')

with FsdbReader('simulation.fsdb') as reader:
    data = reader.load_waveform('tb.dut.data[7:0]', clock='tb.clk')

FsdbReader uses the same API, but requires the Verdi NPI runtime (libNPI.so). See the FSDB installation and runtime setup before opening an FSDB file.

Sampling and windows¶

load_waveform(signal, clock, ...) samples the selected signal on every edge of the clock. By default, wavekit samples on the falling edge to reduce errors caused by sampling during signal transitions. Pass sample_on_posedge=True to sample on rising edges. Use begin_time and end_time for timestamp windows, or begin_cycle and end_cycle for absolute clock-cycle windows. Time and cycle windows cannot be mixed.

Waveforms used together for arithmetic, masking, or pattern matching must use the same clock source, sampling edge, and time or cycle window.

The load_unknown_mask() and load_matched_unknown_masks() methods expose X/Z source bits as unsigned masks. Use these masks to track X/Z states without losing information when unknown values are replaced with xz_value=0.