Verilog define

In Verilog, `define` is a preprocessor directive that allows the user to define a constant or macro for use throughout the Verilog code. It is similar to the `#define` directive in C/C++.

The syntax for defining a constant with `define` is as follows:

`define constant_name constant_value

For example:

`define WIDTH 8

This will define a constant called "WIDTH" with a value of 8.

The syntax for defining a macro with `define` is similar to defining a constant, but it can include parameters:

`define macro_name(parameter_list) macro_body

For example:

`define ADD(a, b) (a + b)

This will define a macro called "ADD" that takes two parameters "a" and "b", and returns their sum.

`define` statements are usually placed at the top of a Verilog module or in a separate file that is included at the top of the module using the `include` directive.