IFACE for devices in a library

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kas1e

Posted on: 2013/4/8 9:21 #1

Home away from home

Question is: should i obtain interfaces for all opening devices in my library ? Why i ask, its because for example for timer.device i have no needs to do that by some reasons. I.e. that kind of code in os4 library works pretty well:


// Open timer

    if (OpenDevice("timer.device",unit,&handle->req.tr_node,0))

    {

        if (handle->my_port) DeleteMsgPort(handle->my_port);

        FreeVec(handle);

        return 0;

    }



    // Initialise timer

    handle->req.tr_node.io_Message.mn_ReplyPort=port;

    handle->req.tr_node.io_Command=TR_ADDREQUEST;

    return handle;

Through when i try to use console.device, i have crashes till a not add IFACE like this:


// Convert a key from the raw key code

BOOL LIBFUNC L_ConvertRawKey(

    REG(d0, USHORT code),

    REG(d1, USHORT qual),

    REG(a0, char *key))

{

    struct Device *ConsoleDevice;

    #ifdef __amigaos4__

    struct ConsoleIFace *IConsole;

    #endif  

    struct IOStdReq console_req;

    BOOL ret=0;



    // Open console device

    if (!OpenDevice("console.device",-1,(struct IORequest *)&console_req,0))

    {

        struct InputEvent event;



        // Get device base pointer

        ConsoleDevice=console_req.io_Device;



        #ifdef __amigaos4__

        IConsole = (struct ConsoleIFace *)GetInterface(ConsoleDevice,"main",1,NULL);

        #endif

        

        // Build fake input event

        event.ie_NextEvent=0;

        event.ie_Class=IECLASS_RAWKEY;

        event.ie_SubClass=0;

        event.ie_Code=code;

        event.ie_Qualifier=qual;

        event.ie_EventAddress=0;



        // Convert key

        if ((RawKeyConvert(&event,key,1,0))>0) ret=1;



        #ifdef __amigaos4__

        DropInterface((struct Interface *)IConsole);

        #endif

        // Close device

        CloseDevice((struct IORequest *)&console_req);

    }



    return ret;

}

Question is: why for timer IFACE is not necessary, but necessary for console.device.

I know that answer will be "obtain IFACE for everything all the time", just interesting to know why there is no needs to do it for timer.device. Also in interest about those ones:

Quote:

clipboard.device
trackdisk.device
diskspare.device
floppy.device
mfm.device
diskspare.device

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tboeckel

Re: IFACE for devices in a library

Posted on: 2013/4/8 9:48 #2

Just popping in

Quote:

Question is: why for timer IFACE is not necessary, but necessary for console.device.

Obtaining an interface is only necessary if you are calling one of the library functions of a device later. RawKeyConvert() is one of console.device's library functions. If you are using device IO only then obtaining the interface is not necessary.

As a thumb rule you must obtain the interface if there is something like this in the code (for m68k):

Quote:

// Get device base pointer
ConsoleDevice=console_req.io_Device;

For m68k the device base is the same as a library base to be able to call these functions. If you need to call timer.device functions like AddTime() or GetSysTime() then you must obtain the interface for timer.device, too.

Quote:

clipboard.device
trackdisk.device
diskspare.device
floppy.device
mfm.device

None of these devices offers any directly callable functions, only regular device IO via DoIO/SendIO/BeginIO is possible.

thomas

Re: IFACE for devices in a library

Posted on: 2013/4/8 10:17 #3

Not too shy to talk

Let the compiler help you:

#define __NOGLOBALIFACE__
#define __NOLIBBASE__

before

#include <proto/xxx.h>

Then the compiler will give you a "unknown symbol xxxBase" and "unknown symbol Ixxx" error for every required library base and interface.

salass00

Re: IFACE for devices in a library

Posted on: 2013/4/8 11:27 #4

Just can't stay away

@thomas

Quote:

#define __NOGLOBALIFACE__
#define __NOLIBBASE__

Or rather just add "-D__NOGLOBALIFACE__ -D__NOLIBBASE__" to the compiler flags. Then you won't have to worry about where to place them in your source code files.

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