HDL Tools

Environment for working with HDLs. This builds a number of tools from source and relies on some scripts to facilitate HDL work.

Programs

All the programs are fetched (as a git submodule, via svn, or as a direct download) and built. You can do this with the included Makefile targets for individual tools:

• verilator -- Build Verilator
• gtkwave -- Build GTKWave

Additional targets include:

• build-all -- Build all the tools
• usage -- list all available build targets
• clean-installed -- remove the installed tools in ./opt/ (this will not respect PREFIX so that you don't nuke your /opt directory)
• clean-downloaded -- remove all downloaded program sources
• mrproper -- remove downloaded program contents

Tools will, by default, be installed in ./opt/. However, you can pass a PREFIX option to the Makefile if for whatever reason you want to install these somewhere else (not advised).

Verilator

Verilog to C++ compiler. This is not required to be built for working with Rocket Chip (it will build its own version of Verilator).

GTKWave

Open source (GPL2) waveform viewer with TCL integration.

Verilog::Perl

Perl tools for working with Verilog netlists.

Scripts

addWavesRecursive.tcl

TCL script that, when passed to GTKWave, will generate a saved waveform view (a .gtkw file) that has all the signals in a given VCD file grouped by module. An example invocation would be:

gtkwave -S addWavesRecursive.tcl dump.vcd > dump.gtkw

You can then start GTKWave using this saved view with:

gtkwave dump.vcd dump.gtkw

After 904555632a5131686c20921593ba7010efece916, this is O(n log n) in the number of signals. Previously, this was O(n^2).

vcd-prune

Perl script to prune a VCD file to only include specific modules (and all their submodules). An example invocation would be:

./vcd-prune dump.vcd -m MyModule -o dump-short.vcd

This will only dump signals contained in MyModule or its submodules. For testing a small part of a huge design (e.g., a RoCC unit attached to Rocket Chip), this can cut down dramatically on the size of the VCD file and the processing time of addWavesRecursive.tcl and startup time of a waveform viewer.

• Verilator -- Verilog to C++ compiler
• GTKWave -- Lightweight waveform viewer
• scripts/
  • addWavesRecursive.tcl -- TCL script for GTKWave that populates the waveform viewer with signals nested into the module hierarchy

gtkwave-helper

Bash script that takes care of the boilerplate operations necessary to launch GTKWavewith addWavesRecursive.

Complexities

This comes up as these tools are intended to be used on large amounts of data

Tool	Complexity	What is N?	Critical Region
addWavesRecursive.tcl	n log n	number of signals	tree merge
vcd-prune	n	number of lines	regex
gtkwave-helper