Assert Statement (AHDL)

The Assert Statement allows you to test the validity of any arbitrary expression that uses parameters, numbers, or evaluated functions, or test the used or unused status of a port.

The following example shows an Assert Statement:

ASSERT (WIDTH > 0)
        REPORT          "Width (%) must be a positive integer" WIDTH
        SEVERITY        ERROR
        HELP_ID         INTVALUE;       -- for internal Altera use only

The Assert Statement has the following characteristics:

• The keyword ASSERT is followed by an arithmetic expression that is optionally enclosed in parentheses (). When the expression is false, the assertion is activated and the message string following the REPORT keyword is displayed in the Processing tab of the Messages window and in the Analysis & Synthesis Messages report. If you do not specify a condition, the assertion is always activated.
• The REPORT keyword is followed by a message string and optional message variables. The message string is enclosed in quotation marks ("), and can include % characters that are substituted with the values of optional message variables. If no REPORT keyword is used, an assertion that is activated displays a generic message of the following format in the Messages window and Report window: Assertion failed
• Optional message variables consist of one or more parameters, evaluated functions, or arithmetic expressions. Multiple message variables are separated by commas (,). The values of the message variables are substituted, in order, for the % characters in the quoted message string. A value can be either a non-negative number or a text string. In the example shown above, the value of WIDTH is substituted for the % in the quoted message string.
• The optional SEVERITY keyword is followed by a severity level of ERROR, WARNING, or INFO. If no severity is specified, the ERROR level is used.
• The HELP_ID keyword and help string are used in some Altera-provided logic functions and are reserved for internal Altera use.
• The statement ends with a semicolon (;).
• The Assert Statement can be used within the Logic Section or outside any other AHDL section.