Tutorial
Charles André, Anthony Gaudino, Benoit Ferrero
Equipe-projet Aoste,
INRIA Sophia-Antipolis et
laboratoire I3S (CNRS/UNSA)
Contact :
Charles.André@i3s.unice.fr
Benoit.Ferrero@sophia.inria.fr
This plug-in displays clock evolutions as waveforms. The
waveforms are described in vcd extension files, generated from a CCSL (Clock
Constraint Specification Language) specification.
How to use Vcd Viewer?
Run
To run the Vcd Viewer you, right click on a vcd file and in the menu Open With select Vcd
Multi-page Editor.
This command launches the editor:
The page Vcd Viewer displays on your screen,
for each clock its names and the associated waveform.
The second page is a text editor, allowing you to read and modify the vcd file (advanced user only!).
Functionality
Displaying
constraints
On the first page the Vcd Viewer can show
constraint(s) between two or more clocks.
If you put the cursor on a clock instant and if this clock is constrained
the viewer displays the relation (textual form) on bottom of the editor.
You can also display constraints in the form of arrows simply clicking
on clock instants.
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Strict precedence
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Precedence
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Coincidence
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Example after a click on the second instant of InWord:
To hide constraints you just re-click on the instant.
In this example arrows displayed represent an alternate between Ready and InWord.
The third arrows linking blue rectangle and InWord instant highlight a precede function.
Example
of an others clock constraints:
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SampledOn |
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FilteredBy |
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Sustains |
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Displaying constraints relies on special comments
included in the vcd file. These comments have a strict syntax. See the Comments part for more
details.
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Zoom
It is possible to zoom with the combination of “Ctrl” key and the wheel
button.
Show,
hide and move clocks
When you open a Vcd Viewer Editor a menu Vcd Editor appears. In this menu select Clock and then Ordering.
This dialog box allows you to add, remove and move clocks using arrows.
Clocks can also be moved by drag and drop on clock names.
Find
This functionality gives access to a given instant of a clock.
To use the find option you click on the Find button in the menu.
Select a clock name and enter the number of the desired instant.
After clicked on OK the instant
highlighted in red.
Ghost Mode
What is
it?
The ghost mode is an option allowing displaying or hiding ghost instants. This kind of instant is
represented by a filled rectangle.
A ghost instant represents a potential instant of the clock (the
clock could have ticked at this time, but its actual tick has been postponed).
The button for display or hide ghost instants, is in submenu Options.
With ghost: Without
ghost:
Time
marker and fireable clock
The time marker is a vertical red line which appears when you click with
the right-button.
The status of a clock under the time marker is reflected in the left
part of the figure.
Light green clock names represent ticking clocks (i.e., clock that actually
ticks), while dark green clock names represent clock with a ghost instant.
Comments
Comments in the vcd file are mandatory for the
correct display of constraints
Syntax for a comment containing a constraint:
$comment constraint statement $end
Syntax for a comment containing a clock state:
$comment status F clock_ident $end
The best solution for generate a good vcd is
to use the plug-in CCSL Parser.