"“参数”和“本地参数”之间的区别"

Question

I'm writing a project with Verilog and want to use parameter<\/code> to define some parameter in my module. But when I read in some source code, localparam<\/code> sometimes is used instead of parameter<\/code> .

Answer 1

Generally, the idea behind the localparam<\/code> (added to the Verilog-2001 standard) is to protect value of localparam<\/code> from accidental or incorrect redefinition by an end-user (unlike a parameter<\/code> value, this value can't be modified by parameter redefinition or by a defparam<\/code> statement).

Answer 2

Minimal example<\/strong>

module myram #(
    parameter WORD_SIZE = 1,
    parameter ADDR_SIZE = 1
) (
    input wire [ADDR_SIZE-1:0] addr,
    inout wire [WORD_SIZE-1:0] data,
    // ...
);
    localparam MEM_SIZE = WORD_SIZE * (1 << ADDR_SIZE);
    // Use MEM_SIZE several times in block.
...