Thank you very much Perl Monks for helping me recently. I have made some progress now.

The problem is: I need the address of a string (binary) to be passed to/from a C function of this type
(void MyFunction(unsigned char *input, unsigned char *output) without giving the length (the length is dealt within the C function. My function just need the address to work fine.

I managed to convert a Perl SV* to an unsigned char* thanks to this typemap:

%typemap(in) (unsigned char *string1) {
   $1 = (unsigned char *)SvPV_nolen($input);
}
[download]

Now I need to do the opposite, it should look like this:

%typemap(out) (unsigned char *output,  const size_t output_length)
{
          $result = newSVpv((char *)$1, $2);
          sv_2mortal($result);
          argvi++;
          delete $1;
}
[download]

but I don't need the length and even with the length I tried this example without success.

Would anyone know how to write this second typemap in order to convert an unsigned char * into a *SV?

Thanks a lot in advance.

Arnaud

Edited by Chady -- added code tags.