+++ /dev/null
-# GTKWave improvements
-
-(Originally at <http://lists.libre-soc.org/pipermail/libre-soc-dev/2020-August/000146.html>)
-
-Lately, I've been investigating about generating better GTKWave "save"
-files (*.gtkw), from Python. The goal is to ease analysis of traces
-generated by unit-tests, and at the same time to better understand the
-inner working of modules, for which we are writing such tests.
-
-I am using src/soc/experiment/alu_fsm.py as a test bed for demonstration.
-
-To see the current work, run:
-
-1) python3 src/soc/experiment/alu_fsm.py
-2) gtkwave test_shifter.gtkw
-
-Besides color, another interesting feature is collapsible group of
-traces. Try selecting the opening brace of the "debug" and "internal"
-groups, and double-click or press T.
-
-Another bonus is string traces, which allows "printf" style debugging in
-the trace pane.
-
-A current limitation is having to deal with signal names instead of
-Signals themselves. Also, direct use of vcd.gtkw is a bit verbose. I
-intend to work a bit on this, next.
-
-Possibly, I'll propose and contribute back improvements to the nMigen
-sim.pysim.Simulator.write_vcd method, which was my inspiration for this
-work.
-
-A more complete description follows:
-
-https://git.libre-soc.org/?p=soc.git;a=commitdiff;h=de64658d0a482f1d6df3c84b4087864ff65ccfef
-
-commit de64658d0a482f1d6df3c84b4087864ff65ccfef
-Author: Cesar Strauss <cestrauss@gmail.com>
-Date: Thu Aug 13 19:40:35 2020 -0300
-
- Demonstrates creating stylish GTKWave "save" files from python
-
- This is inspired on the use of the vcd.gtkw module in nMigen, used
- internally to create "save" files of selected Signals, for
- "Simulator.write_vcd".
-
- However, the vcd.gtkw module exposes a great deal of extra
- possibilities, like:
-
- 1) Individual trace colors.
- For instance, use different color styles for input, output, debug
- and internal traces.
- 2) Numeric bases besides the default hex.
- 3) Collapsible trace groups
- Useful to hide and show, at once, groups of debug, internal and
- sub-module traces.
- Select the opening or closing brace, then use the T key.
- 4) Comments in the signal names pane
- 5) Change the displayed name of a trace
- 6) Sane default for initial zoom level
- 7) Place markers on interesting places
- 8) Put the generating file name as a comment in the file
-
-https://git.libre-soc.org/?p=soc.git;a=commitdiff;h=d3a72bb0688cf343dddc069ef50ba60b9736e8d9
-
-commit d3a72bb0688cf343dddc069ef50ba60b9736e8d9
-Author: Cesar Strauss <cestrauss@gmail.com>
-Date: Fri Aug 14 08:06:49 2020 -0300
-
- Demonstrates adding extra debug signals traces to the dump file
-
- At simulation time, you can declare a new signal, and use it inside
- the test case, as any other signal. By including it in the "traces"
- parameter of Simulator.write_vcd, it is included in the trace dump
- file.
-
- Useful for adding "printf" style debugging for GTKWave.
-
-https://git.libre-soc.org/?p=soc.git;a=commitdiff;h=1d4fa2db3d660510ebeceb650188c6fcf3127fd4
-
-commit 1d4fa2db3d660510ebeceb650188c6fcf3127fd4 (HEAD -> master,
-origin/master, origin/HEAD)
-Author: Cesar Strauss <cestrauss@gmail.com>
-Date: Fri Aug 14 08:25:36 2020 -0300
-
- Demonstrates string traces
-
- When declaring a Signal, you can pass a custom decoder that
- translates the Signal logic level to a string. nMigen uses this
- internally to display Enum traces, but it is available for general
- use.
-
- Some applications are:
- 1) Display a string when a signal is at high level, otherwise show a
- single horizontal line. Useful to draw attention to a time interval.
- 2) Display the stages of a unit test
- 3) Display arbitrary debug statements along the timeline.
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