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#define INCL_DOSDEVIOCTL
 
USHORT DosDevIOCtl(pcTransmitQue, 0L, 0x0069, 0x0001, hDevice)
PUSHORT pcTransmitQue;    /* pointer to structure for character count */
HFILE hDevice;            /* device handle                            */
 
The ASYNC_GETOUTQUECOUNT function retrieves a count of characters in the
transmit queue.
 
Parameter      Description
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pcTransmitQue  Points to the RXQUEUE structure that receives the count of
               characters in the transmit queue.
 
hDevice        Identifies the serial device that receives the device-control
               function. The handle must have been created previously by
               using the DosOpen function.
 
Return Value
 
The return value is zero if the function is successful or an error value if
an error occurs.
 
Comments
 
The device-driver transmit queue is a memory buffer between the memory
pointed to by the write-request packet and the transmit hardware for this
serial device. If the transmit queue is empty, the program may not assume
that all write requests are completed or that no write requests are
outstanding. The behavior of data movement between the write request and the
transmit queue may change from release to release of the device driver.
Programs should not be written to have a dependency on this information.
 
Programs should be written to be independent of the transmit queue being a
fixed size. The information in this field allows the application to get the
size of the transmit queue. The current size of the transmit queue is
approximately 128 bytes but is subject to change.
 
See Also
 
DosOpen, ASYNC_GETINQUECOUNT, RXQUEUE
 
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