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Is it possible to have variable module name which could then be picked by some parameter? I am looking for the syntax for if...else inside a macro definition.

module test;

  `define NAME(x) if (x == 0) mod_e else mod_w
  generate
    for (genvar i = 0; i < 2; i++) begin
      `NAME(i) inst_name (.a(a),.b(b),...);
    end
  endgenerate

endmodule

One way is to do it like below, but it requires connecting all ports 2 times, which is inconvenient for modules with hundreds of IOs and prone to errors.

module test;

  generate
    if (SOME_PARAM == 0) begin
      mod_e inst_name (.a(a),.b(b),...);
    end else begin
      mod_w inst_name (.a(a),.b(b),...);
    end
  endgenerate

endmodule
Wilderness
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  • There's some expression evaluation happening in the port list and the names don't match. I didn't show it here. – Wilderness May 06 '20 at 23:13

2 Answers2

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As a possible solution to your hundreds of ports issues, assuming that all instances have the same set of ports, you can approach this problem differently, by defining an instance macro:

`define INST(mod_name) mod_name inst_name(.a(a), .b(b), ...);

if(SOME_PARAM == 0)
   `INST(mod_e)
else
   `INST(mod_w)
Serge
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You can't use macros to do instance specific mapping. Macros get expanded in a pre-processing step before the generate block is parsed.

The only thing that comes close to this would be the config block, which lets you choose a module of the same name from a different library for a specific instance. But there's no conditional operators.

dave_59
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  • OK, thanks for explaining the difference. I believe Serge's answer below comes close and is a good way to achieve what I am looking for. – Wilderness May 07 '20 at 06:08