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int EnableNotification(cid, hWnd, wInTrigger, wOutTrigger)
int cid;
HWND hWnd;
WORD wInTrigger;
WORD wOutTrigger;
 
The EnableNotification function enables or disables communications message
posting. When enabled, the driver posts the WM_COMMNOTIFY message to the
specified window. USER calls this function when an application calls the
EnableCommNotification function (USER.245).
 
Parameter    Description
────────────────────────────────────────────────────────────────────────────
 
cid          Identifies the communication device.
 
hWnd         Identifies the window to receive the WM_COMMNOTIFY message. If
             this parameter is NULL, the function disables the
             notification.
 
wInTrigger   Specifies the minimum number of bytes to be received in the
             communication device's input buffer before receive notification
             is sent.
 
wOutTrigger  Specifies the maximum number of bytes to remain in the
             communication device's output buffer before transmit
             notification is sent.
 
Return Value
 
The return value is TRUE if successful. Otherwise, the return value is
FALSE.
 
Comments
 
The export ordinal for this function is 100.
 
The WM_COMMNOTIFY message has the following parameters.
 
Parameter       Description
────────────────────────────────────────────────────────────────────────────
wParam          Specifies the communication-device identifier (the cid
                parameter).
 
HIWORD(lparam)  Not used; must be zero.
 
LOWORD(lparam)  Specifies the notification status. It can be one of the
                following values.
 
                Value        Meaning
                ────────────────────────────────────────────────────────────
                CN_EVENT     An event enabled in the communication device's
                             event mask (specified by the SetCommEventMask
                             function) has occurred. The application should
                             call the function GetCommEventMask to determine
                             what event has occurred, and to clear the
                             event.
 
                             This status is sent when the communication
                             device's event word changes. The application
                             clears the appropriate event to ensure
                             notification on subsequent events.
 
                CN_RECEIVE   At least wInTrigger bytes are in the
                             communication device's input buffer, or at
                             least 1 byte is in the input buffer.
                             Additionally, no more have been received before
                             the end of an internal timeout period. The
                             number of bytes in the input buffer must be
                             lower than wInTrigger bytes before this message
                             will be sent again.
 
                CN_TRANSMIT  Fewer than wOutTrigger bytes remain in the
                             communication device's output buffer to be
                             transmitted. The number of bytes in the output
                             buffer must exceed wOutTrigger bytes before
                             this message will be sent again.
 
The communication device event may be a line-status or printer error.
Applications can determine the cause by using the GetCommError function
immediately after the GetCommEventMask function (USER.209).
 
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