Using windows API functions

Using windows API functions

[Antoine JORGE RIBEIRO]

hi!
I desesperatly try to manage with the function ReadFile from Win32.Winbase,
in object ada (Aonix) and I don't understand How to use it and How the
lpBuffer : Win32.lpVoid might be used.
what's lpVoid, How can I Point to an array of Byte (mod 2**8).

Function is as described :
function ReadFile (    hFile                                         :
Win32.winnt.HANDLE;
                                      lpBuffer
: Win32.lpVoid;
                                      nNumberOfBytesToRead     :
Win32.Dword;
                                      lpNumberOfBytesToRead    :
Win32.LPDword;
                                      lpOverlapped
: LPOVERLAPPED)
                                return Win32.BOOL

Thanks for any kind of help

Antoine (a happy newbie)

Re: Using windows API functions

[Martin C. Carlisle]

In article <900065152.385075@dedale.pandemonium.fr>,
Antoine JORGE RIBEIRO <softst1@bruker.fr> wrote:
>hi!
>I desesperatly try to manage with the function ReadFile from Win32.Winbase,
>in object ada (Aonix) and I don't understand How to use it and How the
>lpBuffer : Win32.lpVoid might be used.
>what's lpVoid, How can I Point to an array of Byte (mod 2**8).

Win32Ada binds to C, where one can go from (void *) to (char *) at the
drop of a hat.  In Ada, I'd suggest an Unchecked_Conversion from
your pointer type to Win32.lpvoid.

--Martin

-- 
Martin C. Carlisle, Computer Science, US Air Force Academy
mcc@cs.usafa.af.mil, http://www.usafa.af.mil/dfcs/bios/carlisle.html
DISCLAIMER:  This content in no way reflects the opinions, standard or 
policy of the US Air Force Academy or the United States Government.

Re: Using windows API functions

[Stephen Leake]

mcc@tyrolia.cs.princeton.edu (Martin C. Carlisle) writes:

> In article <900065152.385075@dedale.pandemonium.fr>,
> Antoine JORGE RIBEIRO <softst1@bruker.fr> wrote:
> >hi!
> >I desesperatly try to manage with the function ReadFile from Win32.Winbase,
> >in object ada (Aonix) and I don't understand How to use it and How the
> >lpBuffer : Win32.lpVoid might be used.
> >what's lpVoid, How can I Point to an array of Byte (mod 2**8).
> 
> Win32Ada binds to C, where one can go from (void *) to (char *) at the
> drop of a hat.  In Ada, I'd suggest an Unchecked_Conversion from
> your pointer type to Win32.lpvoid.
> 

Actually, if you read the Win32Ada source code (always a good idea!),
you will find that Win32.lpvoid is just a renaming of System.Address.
Thus to find lpvoid for a buffer:

Data : my_data_type;

use 'address:

ReadFile
(lpBuffer => Data'address,
 ...
);

Have fun!

-- Stephe