DriverCallback
Calls a callback function, sends a message to a window, or unblocks a thread. The action depends on the value of the notification flag. This function is intended to be used only within the DriverProc function of an installable driver.
BOOL DriverCallback(
DWORDdwCallBack,DWORDdwFlags,HDRVRhdrvr, DWORDmsg,DWORDdwUser,DWORDdwParam1,DWORDdwParam2 );
Parameters
dwCallBack
Address of the callback function, a window handle, or a task handle, depending on the flag specified in the dwFlags parameter.
dwFlags
Notification flags. It can be one of these values:
| DCB_NOSWITCH | The system is prevented from switching stacks. This value is only used if enough stack space for the callback function is known to exist. |
| DCB_FUNCTION | The dwCallback parameter is the address of an application-defined callback function. The system sends the callback message to the callback function. |
| DCB_WINDOW | The dwCallback parameter is the handle of an application-defined window. The system sends subsequent notifications to the window. |
| DCB_TASK | The dwCallback parameter is the handle of an application or task. The system sends subsequent notifications to the application or task. |
hdrvr
Handle of the installable driver instance.
msg
Message value.
dwUser
32-bit user-instance data supplied by the application when the device was opened.
dwParam1
32-bit message-dependent parameter.
dwParam2
32-bit message-dependent parameter.
Return Value
Returns TRUE if successful or FALSE if a parameter is invalid or the task's message queue is full.
Remarks
The client specifies how to notify it when the device is opened. The DCB_FUNCTION and DCB_WINDOW flags are equivalent to the high-order word of the corresponding flags CALLBACK_FUNCTION and CALLBACK_WINDOW specified in the lParam2 parameter of the DRV_OPEN message when the device was opened.
If notification is accomplished with a callback function, hdrvr, msg, dwUser, dwParam1, and dwParam2 are passed to the callback function. If notification is accomplished by means of a window, only msg, hdrvr, and dwParam1 are passed to the window.
Requirements
** Windows NT/2000:** Requires Windows NT 3.1 or later.
** Windows 95/98:** Requires Windows 95 or later.
** Header:** Declared in Digitalv.h.
** Library:** Use Winmm.lib.
See Also