Integrate External Code

External code integration using custom fixed-point S-functions

Use custom fixed-point S-functions to integrate external code.

Functions

APIs for Custom Fixed-Point S-Functions

Convert Data Type

`ssFxpConvert`	Convert value from one data type to another
`ssFxpConvertFromRealWorldValue`	Convert value of data type `double` to another data type
`ssFxpConvertToRealWorldValue`	Convert value of any data type to `double`

U32 Bit Region

`ssFxpGetU32BitRegion`	Return stored integer value for 32-bit region of real, scalar signal element
`ssFxpGetU32BitRegionCompliant`	Determine whether S-function is compliant with the U32 bit region interface
`ssFxpSetU32BitRegion`	Set stored integer value for 32-bit region of real, scalar signal element
`ssFxpSetU32BitRegionCompliant`	Declare compliance with the U32 bit region interface for fixed-point data types with 33 or more bits

Registered Data Type Information

`ssGetDataTypeBias`	Return bias of registered data type
`ssGetDataTypeFixedExponent`	Return exponent of slope of registered data type
`ssGetDataTypeFracSlope`	Return fractional slope of registered data type
`ssGetDataTypeFractionLength`	Return fraction length of registered data type with power-of-two scaling
`ssGetDataTypeFxpContainWordLen`	Return word length of storage container of registered data type
`ssGetDataTypeFxpIsSigned`	Determine whether fixed-point registered data type is signed or unsigned
`ssGetDataTypeIsDoubleSingleorHalf`	Determine whether registered data type is double, single, or half-precision data type (Since R2020b)
`ssGetDataTypeFxpWordLength`	Return word length of fixed-point registered data type
`ssGetDataTypeIsFixedPoint`	Determine whether registered data type is fixed-point data type
`ssGetDataTypeIsFloatingPoint`	Determine whether registered data type is floating-point data type
`ssGetDataTypeIsFxpFltApiCompat`	Determine whether registered data type is supported by API for user-written fixed-point S-functions
`ssGetDataTypeIsHalfPrecision`	Determine whether registered data type is half-precision data type (Since R2020b)
`ssGetDataTypeIsScalingPow2`	Determine whether registered data type has power-of-two scaling
`ssGetDataTypeIsScalingTrivial`	Determine whether scaling of registered data type is slope = 1, bias = 0
`ssGetDataTypeNumberOfChunks`	Return number of chunks in multiword storage container of registered data type
`ssGetDataTypeStorageContainCat`	Return storage container category of registered data type
`ssGetDataTypeStorageContainerSize`	Return storage container size of registered data type
`ssGetDataTypeTotalSlope`	Return total slope of scaling of registered data type

Record Information Collected During Simulation

ssLogFixptInstrumentation Record information collected during simulation

Register Fixed-Point Data Type

`ssRegisterDataTypeFxpSlopeBias`	Register data type with [Slope Bias] scaling and return its data type ID
`ssRegisterDataTypeHalfPrecision`	Register half-precision data type and return its data type ID (Since R2020b)
`ssRegisterDataTypeFxpScaledDouble`	Register scaled double data type with [Slope Bias] scaling specified in terms of fractional slope, fixed exponent, and bias, and return its data type ID
`ssRegisterDataTypeFxpFSlopeFixExpBias`	Register fixed-point data type with [Slope Bias] scaling specified in terms of fractional slope, fixed exponent, and bias, and return its data type ID
`ssRegisterDataTypeFxpBinaryPoint`	Register fixed-point data type with binary-point-only scaling and return its data type ID

Topics

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.
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
Using the data type of the input to your S-function to calculate the output data type.

Featured Examples

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

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 Script

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 Script

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

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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