How to pass a struct containing arrays using swig between C and Java?

Question

I have got some way with Swig but the above question is a show stopper for me. I have a fairly complex struct which contains my application data and I need to pass it between C code in the ndroid NDK and Java code at the top level application.

The struct is as follows :

typedef struct
{
    uint16_t    x1;
    char        s1[4][16];
    char        s2[4][16];
    char        s3[4][16];
    uint32_t    x2[4];
    } MY_STRUCT;

It obviously has an unholy brew of multi-dimensional arrays and structure types and I have tried a few things but nothing works.

I need to be able to set and get values in the arrays in both the Java and C code, can anyone tell me the general strategy I should follow to achieve this ?

Thanks,

Boo

Answer 1

You should probably build your set of accessors:

%inline %{
void MY_STRUCT_x1_set(struct MY_STRUCT *obj, uint_16 val) {
   obj->x1 = val;
}
void MY_STRUCT_s1_set(struct MY_STRUCT *obj, int i, int j, char val) {
   obj->s1[i][j] = val;
}
char MY_STRUCT_s2_get(struct MY_STRUCT *obj, int i, int j) {
   return obj->s2[i][j];
}
%}

... and so on. This way you can have full access from Java (through the generated wrappers) to your structure.

Note that SWIG does not perform out-of-bounds or other conditions that may be violated by misuse of the wrapper code.