Embedded coder: How to specify array function input parameter as constant (read only) ?

A certain MatLab function has an array as an input parameter. The function only reads from that array, it never changes its size or writes to it.

When this function is put through the embedded coder, I get:

extern void stepMeasProcessScan(const emxArray_uint8_T *img, ......

which is good: MatLab recognised that my code never changes the input parameter "img".

But: emxArray_uint8_T is generated as follows:

typedef struct emxArray_uint8_T {

    uint8_T *data;
    int32_T *size;
    int32_T allocatedSize;
    int32_T numDimensions;
    boolean_T canFreeData;
} emxArray_uint8_T;

So the generated code cannot change any of the members of this struct, because of the "const". But the generated code could change the data pointed to by the "data" and "size" members, because they lack a "const" in their definition.

As a result, copying a "const uint8_T *" into "data" results in a compiler error.

What I need, is something like:

typedef struct emxArray_const_uint8_T {

    const uint8_T *data;
    const int32_T *size;
    int32_T allocatedSize;
    int32_T numDimensions;
    boolean_T canFreeData;
} emxArray_uint8_T;

Can anybody tell me how to achieve this ?

[TAB]

Are you generating this code from Simulink model or from matlab function ?

[Hank]

I'm generating code with Embedded Coder from a MatLab function. I'm not using Simulink.

[TAB]

Embedded Coder or Matlab Coder..? Embedded Coder generates code from simulink models.

[Kaustubha Govind]

TAB: I think this would be a MATLAB Coder question either way because Simulink/Embedded Coder uses MATLAB Coder technology to generate code from (Embedded) MATLAB Function blocks.

[Hank]

I'm not using Simulink.

Answer 1

[Fred Smith]

This is an oversight in the design. I've created a bug report.

In the mean time, you can work around the problem by using a const cast. Just cast your pointer so that it is not const any more. This is ugly but will allow you to make forward progress.

HTH,

Fred