CommNotifyProc

cCall [CommNotifyProc], <hPort, lReferenceData,     lEvent, lSubEvent>
 

Client-defined callback function that VCOMM calls when the transmit or receive queue passes a specified threshold or a communications event occurs.

• No return value.

hPort

Handle of the communications resource.

lReferenceData

32-bit variable passed to _VCOMM_EnableCommNotification.

lEvent

Event type. Can be one of these values:

Value	Meaning
CN_RECEIVED	The number of bytes in the receive queue has reached the notification threshold for the receive queue.
CN_TRANSMIT	The number of bytes in the transmit queue has fallen below the notification threshold for the transmit queue.
CN_EVENT	An enabled communications event occurred.

Notification thresholds are set by the _VCOMM_EnableCommNotification service. Events are enabled by the _VCOMM_SetCommEventMask service.

lSubEvent

Enabled communications events that were detected, if the lEvent parameter is CN_EVENT. Otherwise, this parameter is ignored. Can be one or more of these values:

Value	Meaning
EV_BREAK	BREAK received.
EV_CTS	CTS changed state.
EV_CTSS	CTS state, as reported in Windows 3.1. To accurately identify the CTS state, use EV_CTSS2.
EV_CTSS2	CTS state.
EV_DSR	DSR changed state.
EV_DSRS	DSR state, as reported in Windows 3.1. To accurately identify the DSR state, use EV_DSRS2.
EV_DSRS2	DSR state.
EV_ERR	Line status error occurred.
EV_PERR	Printer error occurred.
EV_RING	Ring signal detected, as reported in Windows 3.1. To accurately identify the ring signal event, use EV_RING2.
EV_RING2	Ring signal detected.
EV_RingTe	Ring trailing edge indicator.
EV_RLSD	RLSD changed state.
EV_RLSDS	RLSD state.
EV_RXCHAR	Any character received.
EV_RXFLAG1	Received the event character specified by the EvtChar1 field of _DCB.
EV_RXFLAG2	Received the event character specified by the EvtChar2 field of _DCB.
EV_TXEMPTY	Transmit queue empty.
EV_TXCHAR	Any character transmitted.

This function is called at interrupt time with interrupts enabled. Therefore, it must call only asynchronous VxD services and must be reentrant. If you need to disable interrupts, do so for as short a time as possible; otherwise, system performance deteriorates and characters may be lost. For time-consuming operations, it is best to schedule events and have event handlers do most of the processing.

The name CommNotifyProc is a placeholder; this function may have any name. For more information, see _VCOMM_EnableCommNotification.

See Also

_VCOMM_EnableCommNotification, _VCOMM_SetCommEventMask