Integrate External Code

Integrate external code with user-written fixed-point S-functions

Examples and How To

Create MEX-Files

Describes the extra steps that you need to take to create MEX-files for fixed-point S-functions

Get the Input Port Data Type

Within your S-function, you might need to know the data types of different ports, run-time parameters, and DWorks.

Set the Output Port Data Type

You may want to set the data type of various ports, run-time parameters, or DWorks in your S-function.

Interpret an Input Value

Suppose you need to get the value of the signal on your input port to use in your S-function.

Write an Output Value

Suppose you need to write the value of the output signal to the output port in your S-function.

Determine Output Type Using the Input Type

The following sample code from lines 243 through 261 of sfun_user_fxp_asr.c gives an example of using the data type of the input to your S-function to calculate the output data type.

Concepts

Data Type Support

Lists the data types supported by the API and discusses the treatment of integers and data-type-overridden signals

Structure of the S-Function

Displays the basic structure of an S-function that directly handles fixed-point data types

Storage Containers

Discusses the containers used to hold signals in simulation and code generation

Data Type IDs

Describes the creation, assignment, and usage of data type IDs, including how to get and set information about data types in an S-function

Overflow Handling and Rounding Methods

Discusses the tokens you can use to define overflow handling and rounding methods in your fixed-point S-function, and describes the overflow logging structure

API Function Reference

Contains reference pages for the API for user-written fixed-point S-functions in alphabetical order

Featured Examples

Fixed-Point S-Functions: Querying Properties

Fixed-Point S-Functions: Querying Properties

Several ways to use S-functions to probe signal properties. Use this model for simulation only; it does not support code generation.

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Fixed-Point S-Functions: Arithmetic Shift

Fixed-Point S-Functions: Arithmetic Shift

A custom C language S-function written to perform an arithmetic shift. This operation is available in Simulink® with the "Shift Arithmetic" block, which can be used for comparison with this S-function example.

Open Model
Fixed-Point S-Functions: Fixed-Point Source

Fixed-Point S-Functions: Fixed-Point Source

A custom C language S-function written to generate a constant value. This operation is available in Simulink® with the "Constant" block, which can be used for comparison with this S-function example.

Open Model
Fixed-Point S-Functions: Data Type Propagation

Fixed-Point S-Functions: Data Type Propagation

How to propagate fixed-point data types in fixed-point S-Functions. It exercises a custom C language S-function written to enforce data types across multiple signals. This operation is available in Simulink® with the "Data Type Propagation" block, which can be used for comparison with this S-function example.

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Fixed-Point S-Functions: Product and Sum

Fixed-Point S-Functions: Product and Sum

How to exercise a custom C language S-function written to compute a fixed-point "product and sum" operation. To see the source code for the S-function, use the right-click context menu to select "Block Parameters". When the dialog box appears, press the Edit button.

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Fixed-Point Designer Documentation
Support