_VCOMM_Acquire_Port

include vcomm.inc

VxDCall _VCOMM_Acquire_Port, <OFFSET32 szVxDName>, \
    lPortNum, VMId, lFlags>
mov     PortHandle, eax
 

Blocks access to a port by applications running in virtual machines (VMs). A port driver should call this service when its PortOpen function is called.

• Returns a port handle if successful, or zero if the port is already in use.

szVxDName

Address of a null-terminated string specifying the name of the port driver.

lPortNum

Hardware port number. Port numbers 0-7Fh specify COM ports 1-80h.

VMId

Handle of the VM to which ownership of the port is assigned (-1 means the owner is a VxD).

lFlags

Must be zero.