从消息队列中立即获取一条消息，适用设备为emc datadomain 2500存储设备，依据其维护手册

程序清单 L6.25 无等待地从消息队列中取一条消息 void *OSQAccept (OS_EVENT *pevent) { void *msg; OS_Q *pq; OS_ENTER_CRITICAL(); if (pevent->OSEventType != OS_EVENT_TYPE_Q) { (1) OS_EXIT_CRITICAL(); return ((void *)0); } pq = pevent->OSEventPtr; if (pq->OSQEntries != 0) { (2) msg = *pq->OSQOut++; (3) pq->OSQEntries--; if (pq->OSQOut == pq->OSQEnd) { pq->OSQOut = pq->OSQStart; }