Access pointer to struct in Matlab Coder

Hello,

I have a c header file with the following struct and inline function to access the pointer to the struct:

typedef struct {
float field1;
unsigned field2;
} myStruct;

extern myStruct data;

inline myStruct* access_structData (void) {
return &data;
}

I tried to access the pointer to the struct with coder.opaque:

structPtr = coder.opaque('myStruct *','NULL','HeaderFile','struct_header.h')
structPtr = coder.ceval('access_structData')
a = structPtr.field1;

I cannot generate code for this since "??? Attempt to extract field 'field1' from 'coder.opaque'". How can I read and write data to a struct using a pointer? Is there any proper work-arounds?

In c the code for what I try to do would look something like this:

float a = access_structData->field1;

Answer 1

[Darshan Ramakant Bhat]

The struct type is opaque for the MATLAB Coder. So it will not have the information about he fields. Can you please try the below work arounds :

• If you wan to access each fields then write a wrapper to access them like below

float access_struct_field1(void) {
data->field1;
}

unsigned access_struct_field2(void) {
data->field2;
}

then invoke these calls through coder.ceal as necessary.

• Do the struct operation in another wrapper function

Consider you want to do addition of the struct fields, then you can do these operations in another C wrapper function

float myStructOperations(myStruct* aStruct ) {
reutrn (float)(aStruct->field1+aStruct->field2);
}

In MATLAB you can do like below

structPtr = coder.opaque('myStruct *','NULL','HeaderFile','struct_header.h');
structPtr = coder.ceval('access_structData');
output = coder.ceval('myStructOperations',structPtr);

[Philip Bergander]

Thank you, this seems to work.