Specifying VHDL Generics and Verilog Parameters - 2025.2 English - UG1483

You can specify a list of generics to pass to the module when Vitis Model Composer compiles the model into HDL. You can extract values for these generics from mask parameters and propagated port information (for example, port width, type, and rate). This flexible generic assignment supports highly parametric modules that are customized based on the Simulink environment surrounding the black box.

The addGeneric method lets you define the generics passed to your module when the design compiles into hardware. The following code shows how to set a VHDL Integer generic, dout_width, to a value of 12.

addGeneric('dout_width','Integer','12'); 

You can set generic values based on port on propagated input port information (for example, a generic specifying the width of a dynamic output port).

A black box's configuration M-function runs at several different points during model compilation. You can invoke the configuration function before the data types (or rates) propagate to the black box. If you are setting generic values based on input port types or rates, nest addGeneric the calls inside a conditional statement that checks the value of the inputTypesKnown or inputRatesKnown variables. For example, the width of the dout port can be set based on the value of din as follows:

if (this_block.inputTypesKnown) 
  % set generics that depend on input port types 
  this_block.addGeneric('dout_width', ... 
  this_block.port('din').width); 
end 

You can configure generic values based on mask parameters associated with a block box. SysgenBlockDescriptor provides a member variable, blockName, which is a string representation of the black box's name in Simulink. You can use this variable to gain access the black box associated with the particular configuration M-function. For example, assume a black box defines a parameter named init_value. A generic with name init_value can be set as follows:

simulink_block = this_block.blockName; 
init_value = get_param(simulink_block,'init_value'); 
this_block.addGeneric('init_value', 'String', init_value); 

• Copy a black box into a Simulink library or model.
• Break the link on the black box.
• Add the desired parameters to the black box dialog box.