Controlling an Interactive Debugging Session

The following example shows how the debug perspective can appear after the program starts and calls back.

The debug perspective displays the following content:

• The stack appears on the Debug tab in the upper left pane.

  Note: Only single task programs are supported.

  The toolbar on the Debug tab contains icons for standard debugging operations to control the session.

• The code that is the current execution point appears in the middle left pane.

  The variables, breakpoints, registers, and expressions views appear in the upper right pane on individual tabs.

Standard Debugging Operations

Session controls for standard debugging operations appear as options on the Run menu and icons on the toolbar. The main controls are

• Resume

Continue executing until a breakpoint occurs or the program exits. You cannot see variables or registers until a breakpoint occurs. If the program is stopped while waiting for input, you must suspend its execution to examine its running state (variables, memory, registers, and so forth).

• Step into

Go to the next executable statement, whether it is in the same subroutine or a different subroutine. The program "takes a step" of one executable line, as follows:

• • If the next line is in the current routine, the program stops there.

  • If the next line is in a called subroutine, the program stops in the subroutine.

• Step over

  Go to the next executable statement in the current subroutine, with the following considerations:

  • If the next statement is a call to a subroutine, the subroutine executes and returns to the calling routine before the stop occurs, unless a breakpoint occurs in the called subroutine. All breakpoints in the called routines are honored.

  • If the program is stopped on the last line of a subroutine, the program is suspended in the return to the routine that called the current subroutine.

  • If the program is stopped on the last line of the main routine, the program executes until it terminates.

• Step out

If the program is currently in a subroutine, finish executing the current subroutine and stop on the statement that called the subroutine. If the program is currently in the main program,  finish executing the program until it terminates. All breakpoints are honored.

• Terminate

Cause the program to exit and the debugging session to end.

Views for the Debugging Session

The following views of the debugging session are provided on tabs in the upper right pane:

• Variables view

  Shows the variables that are currently in scope. That is, it shows global variables and variables that are local to the current stack frame. If a variable contains other variables (that is, if it is the root of a structure), it is displayed as an expandable node.

• Registers view

  Shows the A, X, and R registers of top stack frame of the program. The registers are global; that is, registers do not change from frame to frame.

• Breakpoints view

  Shows the breakpoints that are set currently. If you have multiple projects in your workspace, the breakpoints for all projects are displayed, not just the breakpoints for the projects being debugged.

• Expressions view

  Contains a list of variables that should be watched independently. You can add them to the watch list from the variables view.

Changing the Value of a Variable

To change the value of a variable in the program, do the following:

1. Select the variable on the Variables view tab by clicking it.
   
   The value appears in the value pane at the bottom of the view.

2. Edit the value in the value pane, as desired.

3. Right-click the value pane and click Assign Value (alternatively, press Ctrl-S).
   
   The value of the variable is changed in the program.

Adding a Variable to the Watch List

To add variables to the watch list, do the following:

1. Select the variable on the Variables view tab by clicking it.

2. Right-click the pane and click Create with Expression.
   
   The variable is added to the watch list on the Expressions view tab.

Adding Variables to the Expression View

Use this feature to monitor the value of a selected variable during debug execution. To add variables to the Expression view, do the following:

Note: Ensure that you are in debug mode to add variables to the Expressions view.

1. Select a variable in the symbol file.

2. Right-click on the selected variable and click Add to watch view.

The selected variable is added to the Expressions view tab. You can view the value of the variable during program execution.