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11.11 Altering Parameters
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11.11 Altering Parameters
Here is an example
of a module that uses a parameter [Verilog LRM3.10, 12.2]:
module Vector_And(Z, A, B);
parameter CARDINALITY = 1;
input [CARDINALITY-1:0] A, B;
output [CARDINALITY-1:0] Z;
wire [CARDINALITY-1:0] Z = A & B;
endmodule
We can override this parameter
when we instantiate the module as follows:
module Four_And_Gates(OutBus, InBusA, InBusB);
input [3:0] InBusA, InBusB; output [3:0] OutBus;
Vector_And #(4) My_AND(OutBus, InBusA, InBusB); // 4 AND gates
endmodule
The parameters of a module have
local scope, but we may override them using a defparam statement
and a hierarchical name, as in the following example:
module And_Gates(OutBus, InBusA, InBusB);
parameter WIDTH = 1;
input [WIDTH-1:0] InBusA, InBusB; output [WIDTH-1:0] OutBus;
Vector_And #(WIDTH) My_And(OutBus, InBusA, InBusB);
endmodule
module Super_Size; defparam And_Gates.WIDTH = 4; endmodule
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