OpenEuphoria

Re: Sequence-Atom-DLL

• Posted by Derek Parnell <ddparnell at bigpond.com> Jun 02, 2003
• 392 views

----- Original Message ----- 
From: <president at insight-concepts.com>
To: "EUforum" <EUforum at topica.com>
Subject: Sequence-Atom-DLL


> 
> 
> Hi,
> 
> I have been practicing creating and using .DLLs with Euphoria and the C 
> Translator.
> 
> I created a small .dll with a procedure File_Compress(sequence infile, 
> sequence outfile, 
> sequence setting)
> 
> When trying to call the procedure from a test application, I get an 
> error "Fatal run-time error: device or file name must be a sequence"
> 
> I tried changing the data to a sequence and then I received and error 
> that arguments to C routines must be atoms.
> 
> My question is how do I pass the sequence to the dll if arguments to C 
> routines must be atoms ?
> 

You might have to pass the 'string' as an address.

So in the calling program you do this...

   atom infileA, outfileA, settingA

   infileA = allocate(length(InFileName) + 1)
   poke(infileA, length(InFileName))
   poke(infileA+1, InFileName)

   outfileA = allocate(length(OutFileName) + 1)
   poke(outfileA, length(OutFileName))
   poke(outfileA+1, OutFileName)

   settingA = allocate(length(Setting) + 1)
   poke(settingA, length(Setting))
   poke(settingA+1, Setting)

   c_proc(comp, {infileA, outfileA, settingA} )

   free(infileA)
   free(outfileA)
   free(settingA)

And in the 'dll' code ...
   
   procedure File_Compress(atom InFile, atom OutFile, atom Setting)
       sequence infilename, outfilename, setttings
       atom len

       len = peek(InFile)
       infilename = peek({InFile+1, len})

       len = peek(OutFile)
       outfilename = peek({OutFile+1, len})

       len = peek(Setting)
       settings = peek({Setting+1, len})

       . . .
   end procedure

This what you would have to do with a C written DLL.

And BTW, this method assumes strings are less than 256 bytes.
-- 
Derek