ASYNC GETLINESTATUS

Returns the transmit data status.

Category: IOCTL_ASYNC (01h)
Function: ASYNC_GETLINESTATUS (65h)

Parameter Packet Format

None. Packet pointer must be NULL.

Data Packet Format

┌───────────────────────────────────────────┐
│Field               Length     C Datatype  │
├───────────────────────────────────────────┤
│Transmit Status     BYTE       UCHAR       │
└───────────────────────────────────────────┘

Transmit Status

Returned as bit-significant values. If the bit is 1, the condition is TRUE. If the bit is 0, the condition is FALSE. The number at the beginning of the description is the bit position number. The bit positions go from least to most significant.

Bit 0: WRITE request packets in progress or queued
Bit 1: Data in the physical device driver transmit queue
Bit 2: Transmit hardware is currently transmitting data
Bit 3: Character waiting to be transmitted immediately
Bit 4: Waiting to automatically transmit an XON
Bit 5: Waiting to automatically transmit an XOFF
Bit 6: Undefined
Bit 7: Undefined

Returns

If the call is made with an invalid Parameter Packet value, a general failure error is reported and valid information is not returned in the Data Packet.

Remarks

If a general failure error is not returned, the physical device driver returns the current transmit status of the COM device.