Question

I’m wrapping a library with SWIG (Python as target). The library functions contains parameters with the datatypes “uint32_t”, “uint8_t”, etc. I want to create the interface as cross-platform as possible, so I want to use the original function signatures in my interface.i file. For example:

uint32_t func(uint32_t a, uint32_t b);

The issue I’m trying to solve is that SWIG won’t recognize the parameter as an integer unless there is a typedef on the uint32_t datatype. Right now I’m using this on the interface file:

typedef unsigned uint32_t;

Removing that typedef line will cause the function not to be callable from the target Python binding:

>>> mylib.func(2, 2)
TypeError: in method 'func', argument 1 of type 'uint32_t'

The previous typedef is OK on my local machine, but might be different on another compiler/platform. Using the directive %include "stdint.h" will raise an error on SWIG:

/usr/include/stdint.h:44: Error: Syntax error in input(1).

Wich makes sense since SWIG is not a full-featured compiler, and can not fully evaluate all the #ifdef on that header.

How can I correctly feed SWIG with the datatypes the compiler is choosing on the stdint.h header? Does in fact make sense to strictly enforce the correct datatypes, or just typedefing all the intX_t to long is OK?

Answer 1

If you want to use these types in your SWIG interface file you can do something like:

%module test
%include "stdint.i"

uint32_t my_function();

Which is an existing SWIG interface has the correct typedefs for your system.