Predefined Evaluated Functions (AHDL)

The following predefined evaluated functions are built into AHDL; that is, no Define Statements are needed to use them:

• The USED function can be used to test whether a port has been used, for example, in an If Generate Statement or a Parameters Statement. USED takes the port name as input and returns a value of FALSE if the port is not used.
• The CEIL function specifies the ceiling of a real number, which is the smallest integer that is equal to or greater than the real number. Although this operation applies to all arithmetic expressions, it is meaningful only for LOG2 and DIV operations in which the result can be a real number.
• The FLOOR function specifies the floor of a real number, which is the largest integer that is equal to or less than the real number. Although this operation applies to all arithmetic expressions, it is meaningful only for LOG2 and DIV operations in which the result can be a real number.

You can use these predefined evaluated functions in arithmetic expressions only; you cannot use evaluated functions in Boolean expressions.