Interfacing to C

["RasikaSrinivasan@gmail.com" <rasikasrinivasan@gmail.com>]

I am building an interface to a C library. This library uses structs
like the following:

typedef struct {
    x : int ;
    y : int }  MyStruct ....

While passing variables of this type to functions, the convention in C
is to pass by value (best of my knowledge).

however when I import a function like:

type MyStruct is record ..... end record ;
pragma Convention(C,MyStruct);

procedure process(var : MyStruct);
pragma Import(C,process);

It appears that Ada passes the var by reference. (Well - I am not able
to tell for sure - just that modifying the binding as follows :

procedure process(varx : int; vary : int);
pragma Import(C,process) ;

works and the previous binding did not.

So the question is - how c(an I force Ada (gnat) to pass a record by
value?

thanks for pointers, srini