Covered - The Verilog Code Coverage Analyzer

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Navigating the Toggle Coverage Window


The verbose toggle window allows the user to see which bits for a given signal have toggled from a 0->1 or a 1->0 during simulation. To display this window, simply click on a highlighted/underlined uncovered signal in the Coverage Viewer of the main window. This will cause the verbose toggle viewer to be created for the specified signal as well as display a "-->" symbol in the Coverage Viewer on the same line as the selected signal. This symbol is simply meant to help the user identify in the Coverage Viewer which signal is currently displayed in the Toggle Viewer window. Figure 1 shows the Toggle Viewer loaded with a 4-bit signal called "err_vec" in which bits 3:2 have successfully toggled from a 0->1.

Figure 1. Verbose Toggle Window

Verbose Toggle Window

Understanding the Layout

The bit vector displayed is a binary bit vector, each value (0 or 1) represents whether that bit in the signal either toggled (1) or did not toggle (0) during simulation. There are two bit vectors displayed for the signal, the top vector shows the 0->1 toggle information while the bottom vector shows the 1->0 toggle information.

The name of the signal along with its MSB:LSB information is displayed at the bottom of the window; however, if the mouse cursor is placed over a specific bit in the toggle box, the MSB:LSB will be changed to show the displayed bit, making it easy for the user to discern exactly which bit has toggled/not toggled. If the width of the signal exceeds the given space for the toggle window, a scrollbar will be allowed to slide left and right to view the rest of the toggle information.

To exit this window, simply click on "Close" button. To see this help page from the toggle window, click on the "Help" button.

Excluding/Including a Signal for Toggle Coverage

The user may exclude/include any uncovered signal in the design for toggle coverage by simply clicking on the "Excluded" checkbutton. If this checkbutton is checked, the summary coverage information will automatically be recalculated and redisplayed in the Main Window Summary Bar and the background color of the underlined signal in the Main Window File Viewer will change from the uncovered background color to the covered background color. However, the signal will still remain underlined, allowing the user to see the verbose toggle coverage information, if necessary. If the "Excluded" checkbutton is unchecked, the summary coverage information and background colors will be readjusted to include the coverage information for this signal.

If the user excludes any signal for toggle coverage in the design, the "Save CDD..." option in the File Menu will be enabled. This allows the user to save the excluded property either back to the CDD file (or to a newly named CDD file). Doing so will allow the user to load the CDD file at a different time and retain the knowledge of which signals have been excluded/included for toggle coverage. Additionally, if a saved CDD file with coverage exclusion is merged with another CDD file, the excluded signal information is preserved for the resulting merged CDD file.

Displaying a New Signal

If the Verbose Toggle Coverage window is currently displayed with a signal, the user may select a new signal in the Coverage File Viewer of the Main window. When a new signal is selected, its value immediately replaces the currently selecting signal value. This feature allows many different signals to be viewed one after the other without having to create/destroy a new window for each signal.

The user may also see the previous or next uncovered signal in the main viewer by clicking either the "<--" button (for previous signal viewing) or the "-->" button (for next signal viewing). Note that the "<--" button will be disabled if there is not a signal previous to the current signal in the given module and the "--> button will be disabled if there is not a signal after the current signal in the given module.