Real-Time Workshop Embedded Coder

Properties of Predefined Custom Storage Classes

The Real-Time Workshop Embedded Coder defines two classes of custom data objects:

• Simulink.CustomParameter: This class is a subclass of Simulink.Parameter. Objects of this class have expanded RTWInfo properties. The properties of Simulink.CustomParameter objects are:
• RTWInfo.StorageClass. This property should always be set to the default value, Custom.
• RTWInfo.CustomStorageClass. This property takes on one of the enumerated values described in Predefined Custom Storage Class Summaries. This property controls the generated storage declaration and code for the object.
• RTWInfo.CustomAttributes. This property defines additional attributes that are exclusive to the class, as described in Class-Specific Storage Class Attributes.
• Value. This property is the numeric value of the object, used as an initial (or inlined) parameter value in generated code.
• Simulink.CustomSignal: This class is a subclass of Simulink.Signal. Objects of this class have expanded RTWInfo properties. The properties of Simulink.CustomSignal objects are:
• RTWInfo.StorageClass. This property should always be set to the default value, Custom.
• RTWInfo.CustomStorageClass. This property takes on one of the enumerated values described in Predefined Custom Storage Class Summaries below. This property controls the generated storage declaration and code for the object.
• RTWInfo.CustomAttributes. This optional property defines additional attributes that are exclusive to the storage class, as described in Class-Specific Storage Class Attributes.

Predefined Custom Storage Class Summaries

The following tables summarize the predefined custom storage classes. The entry for each class indicates

• Name and purpose of the class.
• Whether the class is valid for parameter or signal objects. For example, you can assign the storage class Const to a parameter object. This storage class is not valid for signals, however, since signal data (except for the case of invariant signals) is not constant.
• Whether the class is valid for complex data or nonscalar (wide) data.
• Data types supported by the class.

The first three classes, shown in Table 4-1, insert type qualifiers in the data declaration.

Table 4-1: Const, ConstVolatile, and Volatile Storage Classes  

Class Name	Purpose	Parameters	Signals	Data Types	Complex	Wide
Const	Use const type qualifier in declaration	Y	N	any	Y	Y
ConstVolatile	Use const volatile type qualifier in declaration	Y	N	any	Y	Y
Volatile	Use volatile type qualifier in declaration	Y	Y	any	Y	Y

The second set of three classes, shown in Table 4-2, handles issues of data scope and file partitioning.

Table 4-2: ExportToFile, ImportFromFile, and Internal Storage Classes  

Class Name	Purpose	Parameters	Signals	Data Types	Complex	Wide
ExportToFile	Generate and include files, with user-specified name, containing global variable declarations and definitions	Y	Y	any	Y	Y
ImportFromFile	Include predefined header files containing global variable declarations	Y	Y	any	Y	Y
Internal	Declare and define global variables whose scope is limited to the code generated by the Real-Time Workshop	Y	Y	any	Y	Y

The final three classes, shown in Table 4-3, specify the data structure or construct used to represent the data.

Table 4-3: BitField, Define, and Struct Storage Classes  

Class Name	Purpose	Parameters	Signals	Data types	Complex	Wide
BitField	Embed Boolean data in a named bit field	Y	Y	Boolean	N	N
Define	Represent parameters with a #define macro	Y	N	any	N	N
Struct	Embed data in a named struct to encapsulate sets of data	Y	Y	any	N	Y

Table 4-4: Data Access Storage Classes 

Class Name	Purpose	Parameters	Signals	Data types	Complex	Wide
GetSet	Read and write data using access functions. See GetSet Custom Storage Class for Data Store Memory	N	Y	any	N	Y

Introduction to Custom Storage Classes

Class-Specific Storage Class Attributes