Analyze the Generated Code Interface

Code Interface Report Overview

When you select the Create code generation report option for an ERT-based model, a Code Interface Report section is automatically included in the generated HTML report. The Code Interface Report section provides documentation of the generated code interface, including model entry-point functions and interface data, for consumers of the generated code. The information in the report can help facilitate code review and code integration.

The code interface report includes the following subsections:

Entry-Point Functions — interface information about each model entry-point function, including model_initialize, model_step, and (if applicable) model_reset and model_terminate.
Inports and Outports — interface information about each model inport and outport.
Interface Parameters — interface information about tunable parameters that are associated with the model.
Data Stores — interface information about global data stores and data stores with non-auto storage that are associated with the model.

For limitations that apply to code interface reports, see Code Interface Report Limitations.

For illustration purposes, this section uses the following models:

rtwdemo_configinterface (with the ExportedGlobal Storage Class button selected in the model window) for examples of report subsections
rtwdemo_mrmtbb for examples of timing information
rtwdemo_fcnprotoctrl for examples of function argument and return value information

Generating a Code Interface Report

To generate a code interface report for your model:

Open your model, go to the Code Generation pane of the Configuration Parameters dialog box, and select ert.tlc or an ERT-based System target file, if one is not already selected.
Go to the Code Generation > Report pane of the Configuration Parameters dialog box and select the option Create code generation report, if it is not already selected. The rtwdemo_configinterface, rtwdemo_mrmtbb, and rtwdemo_fcnprotoctrl models used in this section select multiple Report pane options by default. But selecting only Create code generation report, generates a Code Interface Report section in the HTML report.
Alternatively, you can programmatically select the option by issuing the following MATLAB^® command:
```
set_param(bdroot, 'GenerateReport', 'on')
```
If the Code-to-model parameter is selected, the generated report contains hyperlinks to the model. Leave this value selected unless you plan to use the report outside the MATLAB environment.
Build the model. If you selected the Report pane option Open report automatically, the code generation report opens automatically after the build process is complete. (Otherwise, you can open it manually from within the model build folder.)
To display the code interface report for your model, go to the Contents pane of the HTML report and click the Code Interface Report link. For example, here is the generated code interface report for the model rtwdemo_configinterface (with the ExportedGlobal Storage Class button selected in the model window).

For help navigating the content of the code interface report subsections, see Navigating Code Interface Report Subsections. For help interpreting the content of the code interface report subsections, see the sections beginning with Interpreting the Entry-Point Functions Subsection.

Navigating Code Interface Report Subsections

To help you navigate code interface descriptions, the code interface report provides collapse/expand tokens and hyperlinks, as follows:

For a large subsection, the report provides [-] and [+] symbols that allow you to collapse or expand that section. In the example in the previous section, the symbols are provided for the Inports and Interface Parameters sections.
Several forms of hyperlink navigation are provided in the code interface report. For example:
- The Table of Contents located at the top of the code interface report provides links to each subsection.
- You can click each function name to go to its definition in model.c.
- You can click each function's header file name to go to the header file source listing.
- If you selected the Code-to-model parameter for your model, to go to the corresponding location in the model display, you can click hyperlinks for any of the following:
  - Function argument
  - Function return value
  - Inport
  - Outport
  - Interface parameter (if the parameter source is a block)
  - Data store (if the data store source is a Data Store Memory block)

For backward and forward navigation within the HTML code generation report, use the Back and Forward buttons above the Contents section in the upper-left corner of the report.

Interpreting the Entry-Point Functions Subsection

The Entry-Point Functions subsection of the code interface report provides the following interface information about each model entry-point function, including model_initialize, model_step, and (if applicable) model_reset and model_terminate.

Field	Description
Function:	Lists the function name. You can click the function name to go to its definition in `model.c`.
Prototype	Displays the function prototype, including the function return value, name, and arguments.
Description	Provides a text description of the function's purpose in the application.
Timing	Describes the timing characteristics of the function, such as how many times the function is called, or if it is called periodically, and at what time interval. For a multirate timing example, see the following `rtwdemo_mrmtbb` report excerpt.
Arguments	If the function has arguments, displays the number, name, data type, and Simulink^® description for each argument. If you select the Code-to-model parameter for your model, you can click the hyperlink in the description to go to the block corresponding to the argument in the model display. For argument examples, see the `rtwdemo_fcnprotoctrl` report excerpt below.
Return value	If the function has a return value, this field displays the return value data type and Simulink description. If you selected the Code-to-model parameter for your model, you can click the hyperlink in the description to go to the block corresponding to the return value in the model display. For a return value example, see the following `rtwdemo_fcnprotoctrl` report excerpt.
Header file	Lists the name of the header file for the function. You can click the header file name to go to the header file source listing.

For example, here is the Entry-Point Functions subsection for the model rtwdemo_configinterface.

To illustrate how timing information might be listed for a multirate model, here are the Entry-Point Functions and Inports subsections for the model rtwdemo_mrmtbb. This multirate, discrete-time, multitasking model contains Inport blocks 1 and 2, which specify 1-second and 2-second sample times, respectively. The sample times are constrained to the specified times by the Periodic sample time constraint option on the Solver pane of the Configuration Parameters dialog box.

To illustrate how function arguments and return values are displayed in the report, here is the entry-point function description of the model step function for model rtwdemo_fcnprotoctrl.

Interpreting the Inports and Outports Subsections

The Inports and Outports subsections of the code interface report provide the following interface information about each inport and outport in the model.

Field	Description
Block Name	Displays the Simulink block name of the inport or outport. If you selected the Code-to-model parameter for your model, you can click on each inport or outport Block Name value to go to its location in the model display.
Code Identifier	Lists the identifier associated with the inport or outport data in the generated code, as follows: If the data is defined in the generated code, the field displays the identifier text. If the data is declared but not defined in the generated code — for example, if the data is resolved with an imported storage class — the field displays the identifier text prefixed with the label '`Imported data:`'. If the data is neither defined nor declared in the generated code — for example, if model configuration parameter Code interface packaging is set to `Reusable function` — the field displays the text '`Defined externally`'.
Data Type	Lists the data type of the inport or outport.
Scaling	For fixed-point entries, lists the data type and fraction length using Simulink fixed-point data type notation. Note You must have a Fixed-Point Designer™ license to see fixed-point scaling information in the report. For more information on how scaling is represented in the table, see Fixed-Point Data Type and Scaling Notation (Fixed-Point Designer).
Dimension	Lists the dimensions of the inport or outport (for example, `1` or `[4, 5]`).

For example, here are the Inports and Outports subsections for the model rtwdemo_configinterface.

Interpreting the Interface Parameters Subsection

The Interface Parameters subsection of the code interface report provides the following interface information about tunable parameters that are associated with the model.

Field	Description
Parameter Source	Lists the source of the parameter value, as follows: If the source of the parameter value is a block, the field displays the block name, such as `<Root>/Gain2` or `<S1>/Lookup1`. If you selected the Code-to-model parameter for your model, you can click the Parameter Source value to go to the parameter's location in the model display. If the source of the parameter value is a workspace variable, the field displays the name of the workspace variable.
Code Identifier	Lists the identifier associated with the tunable parameter data in the generated code, as follows: If the data is defined in the generated code, the field displays the identifier text. If the data is declared but not defined in the generated code — for example, if the data is resolved with an imported storage class — the field displays the identifier text prefixed with the label '`Imported data:`'. If the data is neither defined nor declared in the generated code — for example, if model configuration parameter Code interface packaging is set to `Reusable function` — the field displays the text '`Defined externally`'.
Data Type	Lists the data type of the tunable parameter.
Scaling	For fixed-point entries, lists the data type and fraction length using Simulink fixed-point data type notation. Note You must have a Fixed-Point Designer license to see fixed-point scaling information in the report. For more information on how scaling is represented in the table, see Fixed-Point Data Type and Scaling Notation (Fixed-Point Designer).
Dimension	Lists the dimensions of the tunable parameter (for example, `1` or `[4, 5, 6]`).

For example, here is the Interface Parameters subsection for the model rtwdemo_configinterface (with the ExportedGlobal Storage Class button selected in the model window).

Interpreting the Data Stores Subsection

The Data Stores subsection of the code interface report provides the following interface information about global data stores and data stores with non-auto storage that are associated with the model.

Field	Description
Data Store Source	Lists the source of the data store memory, as follows: If the data store is defined using a Data Store Memory block, the field displays the block name, such as `<Root>/DS1`. If you selected the Code-to-model parameter for your model, you can click on the Data Store Source value to go to the data store's location in the model display. If the data store is defined using a `Simulink.Signal` object, the field displays the name of the `Simulink.Signal` object.
Code Identifier	Lists the identifier associated with the data store data in the generated code, as follows: If the data is defined in the generated code, the field displays the identifier text. If the data is declared but not defined in the generated code — for example, if the data is resolved with an imported storage class — the field displays the identifier text prefixed with the label '`Imported data:`'. If the data is neither defined nor declared in the generated code — for example, if model configuration parameter Code interface packaging is set to `Reusable function` — the field displays the text '`Defined externally`'.
Data Type	Lists the data type of the data store.
Scaling	For fixed-point entries, lists the data type and fraction length using Simulink fixed-point data type notation. Note You must have a Fixed-Point Designer license to see fixed-point scaling information in the report. For more information on how scaling is represented in the table, see Fixed-Point Data Type and Scaling Notation (Fixed-Point Designer).
Dimension	Lists the dimensions of the data store (for example, `1` or `[1, 2]`).

For example, here is the Data Stores subsection for the model rtwdemo_configinterface (with the ExportedGlobal Storage Class button selected in the model window).

Code Interface Report Limitations

The following limitations apply to the code interface section of the HTML code generation reports.

The code interface report does not support the GRT interface with an ERT target or C++ class code interface packaging. For these configurations, the code interface report is not generated and does not appear in the HTML code generation report Contents pane.
The code interface report supports data resolved with most storage classes, except when the storage class properties are set in any of the following ways:
- The storage class property Type is set to FlatStructure. For example, the BitField and Struct storage classes in the Simulink package have Type set to FlatStructure.
- The storage class property Type is set to Other. For example, the GetSet storage class in the Simulink package has Type set to Other.
- The storage class property Data access is set to Pointer, indicating that imported symbols are declared as pointer variables rather than simple variables. This property is accessible only when the storage class property Data scope is set to Imported or Instance-specific.
In these cases, the report displays empty Data Type and Dimension fields.
For outports, the code interface report cannot describe the associated memory (data type and dimensions) if the memory is optimized. In these cases, the report displays empty Data Type and Dimension fields.
The code interface report does not support data type replacement using the Code Generation > Data Type Replacement pane of the Configuration Parameters dialog box. The data types listed in the report will link to built-in data types rather than their specified replacement data types.