- Changed asynch queue insertion and removal to use a lock free algorithm based only on InterlockedCompareExchangePointer. We can now use this lock free approach on IA64 host systems as well.

- Removed flawed logic which assumed that sim_interval was meaningful when referenced by an asynchronous thread.
- Adjust the event_time of events removed from the asynch queue to account for the average time spent on the queue before the event was noticed by the instruction execution thread.
- Added a sim_activate_notbefore function which specifies an rtime which is the earliest time the event should fire.
- Changed the 'wakeup from idle' logic to force an immediate asynch queue check if the wakeup was not due to a timeout (i.e. it was due to an asynch queue insertion).
- Fixed the descrip.mms to build asynchronous support on AXP and IA64 VMS with kernel threads enabled

VAX/vax_cpu.c

@@ -626,7 +626,7 @@ for ( ;; ) {
         }
     fault_PC = PC;
     recqptr = 0;                                        /* clr recovery q */
-    AIO_CHECK_EVENT;
+    AIO_CHECK_EVENT;                                    /* queue async events */
     if (sim_interval <= 0) {                            /* chk clock queue */
         temp = sim_process_event ();
         if (temp)