System Object Considerations for HLS Code Generation

You can generate HLS code in from your system that contains user-defined System object™ by using HDL Coder™.

Usage Rules and Limitations for System object for Generating Code

The following usage rules and limitations apply to using System object in code generated from MATLAB®.

Object Construction and Initialization

  • If objects are stored in persistent variables, initialize System objects once by embedding the object handles in an if statement with a call to isempty().

  • Set arguments to System object constructors as compile-time constants.

  • Initialize all System object properties that releaseImpl uses before the end of setupImpl.

  • You cannot initialize System object properties with other MATLAB class objects as default values in code generation. You must initialize these properties in the constructor.

Inputs and Outputs

  • System object accept a maximum of 1024 inputs. A maximum of eight dimensions per input is supported.

  • The data type of the inputs should not change.

  • The complexity of the inputs should not change.

  • Do not pass a System object as an example input argument to a function being compiled with codegen.

  • Do not pass a System object to functions declared as extrinsic (functions called in interpreted mode) using the coder.extrinsic function. System objects returned from extrinsic functions and scope System objects that automatically become extrinsic can be used as inputs to another extrinsic function. But, these functions do not generate code.

Properties

  • In MATLAB System blocks, you cannot use variable-size for discrete state properties of System objects. Private properties can be variable-size.

  • Objects cannot be used as default values for properties.

  • You can only assign values to nontunable properties once, including the assignment in the constructor.

  • Nontunable property values must be constant.

  • For fixed-point inputs, if a tunable property has dependent data type properties, you can set tunable properties only at construction time or after the object is locked.

  • For getNumInputsImpl and getNumOutputsImpl methods, if you set the return argument from an object property, that object property must have the Nontunable attribute.

Global Variables

  • Global variables are not allowed in a System object.

Methods