include vcomm.inc
VxDCall _VCOMM_GetCommQueueStatus, <hPort, <OFFSET32 cmst>>
or eax, eax
jz error_handler
Retrieves information about the status of a communications channel and the amount of data in the receive and transmit queues. Uses the C calling convention. This is an asynchronous service.
_COMSTAT, _VCOMM_GetLastError