OpenEuphoria

2. Re: Accessing EHLLAPI DLL files

• Posted by pete_stoner at btconnect.com Sep 10, 2003
• 606 views

Thats what I call a quick reply, thanks Matt, you're a star!
Time for me to do some more playing...........

----- Original Message ----- 
From: "Matt Lewis" <matthewwalkerlewis at yahoo.com>
To: "EUforum" <EUforum at topica.com>
Subject: RE: Accessing EHLLAPI DLL files


>
>
> > From: pete_stoner at btconnect.com [mailto:pete_stoner at btconnect.com]
>
> > >The EHLLAPI entry point (hllapi) is always called with the following
> > >four
> > parameters:
> > >1.EHLLAPI Function Number (input)
> > >2. Data Buffer (input/output)
> > >3. Buffer Length (input/output)
> > >4. Position (input); Return Code (output)
> >  >   The prototype for the EHLLAPI is; (long hllapi(LPINT,
> > LPSTR, LPINT,
> > LPINT)"
> > > Each parameter is passed by reference not by value...... (etc etc)
> >
> > My first problem is that I always get an error (-1) from my
> > define_c_function . The function I am calling is not listed
> > in the DLL I have to call, I am assuming that it must be in
> > another DLLs that the first one links to (?), also the book
> > says I have to call the function by number (I still don't
> > fully understand if I am defining it correctly) i.e. ehlapi =
> > open_dll("EHLAPI32.DLL") ConnectPS = define_c_func(ehlapi,
> > "1", {C_INT, C_POINTER, C_INT}, C_INT)
> >
> > The ref book goes on to say..
> > >All the parameters in the hllapi call are pointers and the
> > return code
> > >of
> > the EHLLAPI function is returned in the value of the 4th
> > parameter, not as the value of the function.. Which would
> > suggest that I cannot get the return code with just the
> > normal ret = c_func(ConnectPS....
>
> OK, let's start with the function prototype:
>
> long hllapi(LPINT, LPSTR, LPINT,LPINT)
>
> This tells us that it returns a long value (probably an error indicator
for
> hllapi itself, not the function you're calling).  The other parameters are
> all pointers, do your define_c_func should look like:
>
> xhllapi = define_c_func( elhapi, "hllapi", repeat(C_POINTER,4), C_INT )
>
> Any function you want to call, you will need to call through the hllapi
> function.  First, you need to allocate space in order to poke the values
for
> hllapi:
>
> func_no = allocate(4)
> buffer = allocate( 256 )
> buffer_len = allocate(4)
> position_return = allocate(4)
>
> Then poke the values for the function (assuming that ConnectPS is function
> #1):
>
> poke4( func_no, 1 )
> poke( buffer, your_input_data )
> poke4( buffer_len, 256 )
> poke4( position_return, whatever_this_means )
>
> ret = c_func( xhllapi, {func_no,buffer,buffer_len,position_return} )
>
> -- to see what the return value was:
> ? peek4s( position_return )
>
>
> You should use whatever buffer size that makes sense.  Also, you should
> check it after calling, because hllapi will probably tell you if it needs
> more room to return whatever it was going to return in the buffer (if
> anything--you'll have to read the documentation on each routine).  I'm not
> sure what #4, Position means to hllapi, so I can't help you out there.
>
> Matt Lewis
>
> --^----------------------------------------------------------------
> This email was sent to: pete_stoner at btconnect.com
>