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.
BOOLEAN DriverCallback(DWORD dwCallBack, DWORD
dwFlags, HDRVR hdrvr,
DWORD msg, DWORD dwUser, DWORD
dwParam1, DWORD dwParam2);
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 and 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.