Verilog defines macros as follows:
'define TESTEQ1 4'b1101
The defined macro is referenced later, as follows:
if (request == 'TESTEQ1)
The 'ifdef and 'endif constructs do the following:
°Determine whether a macro is defined.
°Define conditional compilation.
If the macro called out by 'ifdef is defined, that code is compiled.
•If the macro has not been defined, the code following the 'else command is compiled.
•The 'else is not required, but 'endif must complete the conditional statement.
Use the Verilog Macros command line option to define (or redefine) Verilog macros.
•Verilog Macros let you modify the design without modifying the HDL source code.
•Verilog Macros is useful for IP core generation and flow testing.