OpenEuphoria

Re: Sequence-Atom-DLL

• Posted by Robert Craig <rds at RapidEuphoria.com> Jun 02, 2003
• 406 views

jbrown105 at speedymail.org wrote:
> On Mon, Jun 02, 2003 at 05:34:53PM -0400, Robert Craig wrote:
>>When calling a .dll routine that's written in Euphoria,
>>you can pass any kind of Euphoria data as arguments to
>>the routine, but you must declare the routine using
>>define_c_proc/func and the E_ types (E_INTEGER, E_ATOM, ...),
>>not the C_ types (C_INT, ...).
>>e.g.
>>     fc = define_c_proc(lib, "File_Compress",
>>                        {E_SEQUENCE, E_SEQUENCE, E_SEQUENCE})
>>
>>     c_proc(fc, {"infile.dat", "outfile.dat", {1,2,3}})
> 
> Just wondering ... if i wrote a C program, and wanted to use an Eu .dll
> in it ... how would I call the Eu routine in the translated .dll, and how
> would I pass it the parameters?

It's pretty easy as long as the Euphoria routine is
declared with integer parameters (only), and it returns
an integer as a result (if anything). It will look just like a
C routine that takes int's and returns an int.
A C program (after dynamically linking with the Euphoria .dll)
could pass int's, up to 31-bits in size and get back
a 31-bit int as a result. C and Euphoria agree on the meaning
of integers up to 31-bits. Anything else is incompatible.

Someone who studied the internal representation of sequences,
might be able to allocate and construct a sequence in C,
and pass it in, but that's definitely not for the
faint of heart.  

Regards,
    Rob Craig
    Rapid Deployment Software
    http://www.RapidEuphoria.com