The Tcl Debugger

We would like to thank Gregor Schmid for making TDebug available for use in the public domain.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of FITNESS FOR A PARTICULAR PURPOSE.

Starting the debugger

Select Macro > Tcl Debugger (Main window) to run the debugger. Make sure you use the ModelSim and TDebug menu selections to invoke and close the debugger. If you would like more information on the configuration of TDebug see Help > Technotes > tdebug.

The following text is an edited summary of the README file distributed with TDebug.

How it works

TDebug works by parsing and redefining Tcl/Tk-procedures, inserting calls to `td_eval' at certain points, which takes care of the display, stepping, breakpoints, variables etc. The advantages are that TDebug knows which statement in what procedure is currently being executed and can give visual feedback by highlighting it. All currently accessible variables and their values are displayed as well. Code can be evaluated in the context of the current procedure. Breakpoints can be set and deleted with the mouse.

Unfortunately there are drawbacks to this approach. Preparation of large procedures is slow and due to Tcl's dynamic nature there is no guarantee that a procedure can be prepared at all. This problem has been alleviated somewhat with the introduction of partial preparation of procedures. There is still no possibility to get at code running in the global context.

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