This chapter describes how to develop SQ files for SysQuake LE, the
free, limited version of SysQuake. For more information about how SysQuake
LE is licensed and how it can be acquired, please read the license file
which accompanies it.
To preserve SysQuake's commercial viability (and indirectly SysQuake LE's),
SysQuake LE has the following limitations:
- No low-level input/output
- Access to the file system is disabled. This has the benefit of preventing a
malicious SQ file downloaded on the Internet from accessing and corrupting your files.
- No extensions
- Extensions are not loaded. Extensions are files which add new commands
to LME, the language of SysQuake, e.g. for mathematical functions, for connection
to hardware or for your own code developed in C. An example of such an extension
file is LMELapack, which adds high-quality linear
algebra functions based on the de-facto standard library LAPACK. Access to
serial ports, though, has been integrated on some platforms.
- Lower limit on the number of windows open simultaneously
- On some platforms (such as Mac OS 9 and X), several SysQuake programs
(SQ files) may be open simultaneously in different windows (on other platforms
such as Windows, SysQuake itself can be launched more than once). SysQuake LE has
a lower limit on the maximum number of windows.
- No support for advanced data exchange
- To make easier the exchange of data between SysQuake applications or
with other software, SysQuake supports an advanced mechanism based on the
Copy/Paste paradigm. Data conversion is performed when necessary in a
transparent way.
SysQuake LE can be used as a viewer
to illustrate complicated problems with dynamic graphics, or as a development
environment for simple applications.
SysQuake LE as a viewer
As a viewer, SysQuake LE lets the user load interactive graphics and
play with them to acquire a better, intuitive understanding of the meaning of the
graphics. Files can be located locally on the hard disk or the cd-rom of
the computer SysQuake LE runs on, or on the World Wide Web; in this case, the Web browser may
be configured to launch SysQuake LE automatically when a link to an
interactive graphic is clicked.
To use it effectively as a viewer, you must understand the role of SQ files
(the "programs" of SysQuake)
and SQD files (files which store the data and the state of an interactive session
with SysQuake). As a viewer, it is better to prepare SQ files, because no
assumption about the availability or location of SQ files is necessary.
There are mainly three ways to prepare SQ files before distributing them
to illustrate theory with interactive graphics:
- No programming
- SysQuake is provided with SQ files which cover a large area of classical
automatic control, signal processing, and other fields. You can open them (or an
SQD file you have already saved), modify the settings until you are satisfied,
and save the result as a new SQ file (in the File menu, select "Save As SQ File";
with some versions, select "Save As" and choose the SQ File format).
- Editing existing SQ files
- If you have an SQ file with most of the features you want, you can modify it
to make it more suitable for SysQuake LE. For example, you can change
the figure names (replacing "Result" with "Correlation between
sin(t) and sign(sin(t))"), or the color of the curves. To make the SQ file
smaller, you can replace the content of the data block with new settings in
the init handler. You can also remove some of the menu handlers, the definitions
of figures which are not displayed, and the functions which are never called.
- Writing new SQ files from scratch
- Writing an SQ file from scratch is of course also an option.
SysQuake LE as a development environment
Developing for SysQuake LE is very similar to developing for SysQuake.
The lack of low-level file access and of the advanced data exchange mechanism
makes more difficult to exchange data seamlessly with other applications.
Copyright 1998-2001, Calerga.
All rights reserved.