When you want to debug a design, it is very useful to watch the digital waves. GHDL can generate a waveform file and now support two formats.
The first format is VCD (Value Change Dump), which is an open format defined by Verilog. The specification of the format are defined by the Verilog LRM. VCD is an ASCII format, so VCD files grow quickly. Most (all) of the waveform viewers support VCD.
You can generate a VCD file from your design by using the --vcd=filename option. Refer to the GHDL document for more details.
Since VCD is Verilog oriented, it is not possible to dump all the VHDL types with VCD. Furthermore, there is no open waveform file format for VHDL. That's the reason why I have created the GHDL Waveform format.
The second format is the GHDL Waveform format. It is a binary format, whose specifications are not yet fully frozen.
Recent versions of GTKWave can read this format. Do not forget to set hier_max_level to 0 to see the full signal name. Also, vectors are always expanded.
Copyright (C) 2005 Tristan Gingold -- tgingold AT free DOT fr
Last modified: Tue Dec 20 09:44:21 CET 2005