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7.4.8.8 Creating an Ada Spec for the DLL Services ¶

A DLL typically comes with a C/C++ header file which provides the definitions of the routines and variables exported by the DLL. The Ada equivalent of this header file is a package spec that contains definitions for the imported entities. If the DLL you intend to use does not come with an Ada spec, you have to generate such a spec yourself. For example, if the header file of API.dll is a file api.h containing the following two definitions:

int some_var;
int get (char *);

then the equivalent Ada spec could be:

with Interfaces.C.Strings;
package API is
   use Interfaces;

   Some_Var : C.int;
   function Get (Str : C.Strings.Chars_Ptr) return C.int;

private
   pragma Import (C, Get);
   pragma Import (DLL, Some_Var);
end API;