Code Generation for Enumerations - MATLAB & Simulink (original) (raw)

Enumerations represent a fixed set of named values. Enumerations help make your MATLAB® code and generated C/C++ code more readable. For example, the generated code can test equality with code such as if (x == Red) instead of using strcmp. To generate C/C++ code, you must have Simulink® Coder™.

When you use enumerations in a MATLAB Function block, adhere to these restrictions:

Define Enumerations for MATLAB Function Blocks

You can define enumerations for MATLAB Function blocks in two ways:

If you define an enumerated type in a class definition file, the class must derive from one of these base types: Simulink.IntEnumType, int8, uint8,int16, uint16, int32, oruint32. Then, you can exchange enumerated data betweenMATLAB Function blocks and other Simulink blocks in a model.

If you use Simulink Coder to generate C/C++ code, you can use the enumeration class base type to control the size of an enumerated type in generated C/C++ code. You can:

The base type determines the representation of the enumerated type in generated C/C++ code.

If the base type is Simulink.IntEnumType, the code generator produces a C enumeration type. Consider the following MATLAB enumerated type definition:

classdef LEDcolor < Simulink.IntEnumType enumeration GREEN(1), RED(2) end end

This enumerated type definition results in the following C code:

typedef enum {
  GREEN = 1,                          
  RED
} LEDcolor;

For built-in integer base types, the code generator produces a typedef statement for the enumerated type and#define statements for the enumerated values. Consider the following MATLAB enumerated type definition:

classdef LEDcolor < int16 enumeration GREEN(1), RED(2) end end

This enumerated type definition results in the following C code:

typedef int16_T LEDcolor;

#define GREEN                          ((LEDcolor)1)             
#define RED                            ((LEDcolor)2)

To customize the code generated for an enumerated type, see Customize Simulink Enumeration.

Allowed Operations on Enumerations

For code generation, you are restricted to the operations on enumerations listed in this table.

Operation Example Notes
assignment operator: = xon = LEDcolor.GREEN xoff = LEDcolor.RED —
relational operators: < > <= >= == ~= xon == xoff Code generation does not support using == or ~= to test equality between an enumeration member and a string array, a character array, or a cell array of character arrays.
cast operation double(LEDcolor.RED) —
conversion to character array or string y = char(LEDcolor.RED); y1 = cast(LEDcolor.RED,'char'); y2 = string(LEDcolor.RED); You can convert only compile-time scalar valued enumerations. For example, this code runs in MATLAB, but produces an error in code generation:y2 = string(repmat(LEDcolor.RED,1,2));The code generator preserves enumeration names when the conversion inputs are constants. For example, consider this enumerated type definition:classdef AnEnum < int32 enumeration zero(0), two(2), otherTwo(2) end endGenerated code produces "two" fory = string(AnEnum.two) and "otherTwo" fory = string(AnEnum.otherTwo)
indexing operation m = [1 2] n = LEDcolor(m) p = n(LEDcolor.GREEN) —
control flow statements: if, switch, while if state == sysMode.ON led = LEDcolor.GREEN; else led = LEDcolor.RED; end —

MATLAB Toolbox Functions That Support Enumerations

For code generation, you can use enumerations with these MATLAB toolbox functions:

See Also

MATLAB Function