selecting parameter based on reg value - verilog

The reg value can to be fed to the module as input port to allow selection of a specific parameter inside the module. Or select the parameter outside the module and give the actual paramter value to the modulethrough a port.

THanks for the reply . Can you please suggest me with an example or sample code ?

You can't select a parameter for a module override dynamically using a variable. Parameter values can only be made up of expressions of constants and other parameters. Did you really mean sel_value is the output of a register, or can it be another constant parameter?

1. If you can use SystemVerilog (yes if you are using ModelSim; no if you are synthesizing and your synthesis tool does not support SV yet), You can declare a array of constants: parameter int my_constants
2. You can concatenate your constants into one big vector and then do a part select to get the constant you want: parameter reg
3. You can declare as many constants you need as individual parameters to the module, and then use a case statement to select which parameter you want.

module1# (my_constants) module1_inst(); // SystemVerilog
module1# (my_constants) module1_inst(); // Verilog vector
case (sel_value) // conditional generate block
  0: module1# (constant0) module1_inst();
  1: module1# (constant1) module1_inst();
  2: module1# (constant2) module1_inst();
  3: module1# (constant3) module1_inst();
endcase

module1# (my_constants) module1_inst(sel_value); // SystemVerilog or Verilog vector
module1# (constant1,constant2,constant3,constant4) module1_inst(sel_value); // case statement inside module1

Hi dave_59 ,

module1# (constant1,constant2,constant3,constant4) module1_inst(sel_value); // case statement inside module1

parameter selected_value =100 ;
case(sel_value)
000: selected_value = constant1 ;
111:selected_value = constant2 ;
etc

You cannot dynamically change the value of a parameter. Just like you can have constant array and then dynamically select an element, you could have a function call with a case statement inside it, or you could put the case statement inside an always block.