ID:10638 VHDL exponentiation error at <location>: operator not supported for the specified operands, <text>

CAUSE: Exponentiation support is limited. The limitations are as follows:

Either the exponent or the base must be a constant.
The exponent must be a positive integer if the base is an integer.
For non-constant exponents the base must be a power of 2.

ACTION: Change the expression to fit the restrictions. Here is some example syntax:

2**n, where n is a non-constant
8**n, where n is a non-constant
var**c, where var is any value and c is constant