down

The down command searches for signal transitions or values in the specified List window. It executes the search on signals currently selected in the window, starting at the time of the active cursor. The active cursor moves to the found location.

Use this command to move to consecutive transitions or to find the time at which a signal takes on a particular value, or an expression of multiple signals evaluates to true. See the up command for related functionality.

The procedure for using down includes three steps: click on the desired signal; click on the desired starting location; issue the down command. (The seetime command can initially position the cursor from the command line, if desired.)

Returns: <number_found> <new_time> <new_delta>

Syntax

down

[-expr {<expression>}] [-falling] [-noglitch] [-rising]
[-value <sig_value>] [-window <wname>] [<n>]

Arguments

-expr {<expression>}

The List window will be searched until the expression evaluates to a boolean true condition. Optional. The expression may involve more than one signal, but is limited to signals that have been logged in the referenced List window. A signal may be specified either by its full path or by the shortcut label displayed in the List window.

See "GUI_expression_format" for the format of the expression. The expression must be placed within curly braces.

-falling

Searches for a falling edge on the specified signal if that signal is a scalar signal. If it is not a scalar signal, the option will be ignored. Optional.

-noglitch

Specifies that delta-width glitches are to be ignored. Optional.

-rising

Searches for a rising edge on the specified signal if that signal is a scalar signal. If it is not a scalar signal, the option will be ignored. Optional.

-value <sig_value>

Specifies a value of the signal to match. Optional. Must be specified in the same radix that the selected signal is displayed. Case is ignored, but otherwise the value must be an exact string match -- don't-care bits are not yet implemented.

-window <wname>

Specifies an instance of the List window that is not the default. Optional. Otherwise, the default List window is used. Use the view command to change the default window.

<n>

Specifies to find the nth match. Optional. If less than n are found, the number found is returned with a warning message, and the marker is positioned at the last match.

Examples

down -noglitch -value FF23

Finds the next time which the selected vector transitions to FF23, ignoring glitches.

down

Goes to the next transition on the selected signal.

The following examples illustrate search expressions that use a variety of signal attributes, paths, array constants, and time variables. Such expressions follow the "GUI_expression_format" and can be built with the aid of the "The GUI Expression Builder" .

down -expr {clk'rising && (mystate == reading) && (/top/u3/addr == 32'habcd1234)}

Searches down for an expression that evaluates to a boolean 1 when signal clk just changed from low to high and signal mystate is the enumeration reading and signal
/top/u3/addr is equal to the specified 32-bit hex constant.

down -expr {(/top/u3/addr and 32'hff000000) == 32'hac000000}

Searches down for an expression that evaluates to a boolean 1 when the upper 8 bits of the 32-bit signal /top/u3/adder equals hex ac.

down -expr {((NOW > 23 us) && (NOW < 54 us)) && clk'rising && (mode == writing)}

Searches down for an expression that evaluates to a boolean 1 when logfile time is between 23 and 54 microseconds, and clock just changed from low to high and signal mode is enumeration writing.

See also

"GUI_expression_format" , view, seetime, up

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