Computer for executing I/O instructions, by emulation, in a foreign application program wherein the emulator result thread is blocked from running between processes

摘要

A computer for executing I/O instructions, by emulation, in a foreign application program includes an emulator program which has a Send thread, a Get thread, and single Result thread. The Send thread calls into a native operating system for the computer to send data from the foreign application program to an I/O port. The Get thread calls into the native operating system to receive data from the I/O port for the foreign application program. The Result thread processes one result descriptor from the native operating system when data is sent for the Send thread, and processes another result descriptor from the native operating system when data is received for the Get thread, and is completely blocked from running on the computer between the processing of the result descriptors. These threads are cleared, asynchronously with respect to the transfer of any data, by sending a CLEAR command from the emulator to the native operating system which responds by unblocking the Result thread and sending it a dummy result descriptor.