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31 #ifndef __MEM_TPORT_HH__
32 #define __MEM_TPORT_HH__
37 * Declaration of SimpleTimingPort.
40 #include "mem/port.hh"
41 #include "sim/eventq.hh"
46 * A simple port for interfacing objects that basically have only
47 * functional memory behavior (e.g. I/O devices) to the memory system.
48 * Both timing and functional accesses are implemented in terms of
49 * atomic accesses. A derived port class thus only needs to provide
50 * recvAtomic() to support all memory access modes.
52 * The tricky part is handling recvTiming(), where the response must
53 * be scheduled separately via a later call to sendTiming(). This
54 * feature is handled by scheduling an internal event that calls
55 * sendTiming() after a delay, and optionally rescheduling the
56 * response if it is nacked.
58 class SimpleTimingPort : public Port
61 /** A list of outgoing timing response packets that haven't been
63 std::list<PacketPtr> transmitList;
66 * This class is used to implemented sendTiming() with a delay. When
67 * a delay is requested a new event is created. When the event time
68 * expires it attempts to send the packet. If it cannot, the packet
69 * is pushed onto the transmit list to be sent when recvRetry() is
71 class SendEvent : public Event
73 SimpleTimingPort *port;
77 SendEvent(SimpleTimingPort *p, PacketPtr pkt, Tick t)
78 : Event(&mainEventQueue), port(p), packet(pkt)
79 { setFlags(AutoDelete); schedule(curTick + t); }
81 virtual void process();
83 virtual const char *description()
84 { return "Future scheduled sendTiming event"; }
88 /** Number of timing requests that are emulating the device timing before
89 * attempting to end up on the bus.
93 /** If we need to drain, keep the drain event around until we're done
97 /** Schedule a sendTiming() event to be called in the future. */
98 void sendTimingLater(PacketPtr pkt, Tick time)
99 { outTiming++; new SendEvent(this, pkt, time); }
101 /** This function is notification that the device should attempt to send a
103 virtual void recvRetry();
105 /** Implemented using recvAtomic(). */
106 void recvFunctional(PacketPtr pkt);
108 /** Implemented using recvAtomic(). */
109 bool recvTiming(PacketPtr pkt);
112 * Simple ports generally don't care about any status
113 * changes... can always override this in cases where that's not
115 virtual void recvStatusChange(Status status) { }
120 SimpleTimingPort(std::string pname)
121 : Port(pname), outTiming(0), drainEvent(NULL)
124 /** Hook for draining timing accesses from the system. The
125 * associated SimObject's drain() functions should be implemented
126 * something like this when this class is used:
128 PioDevice::drain(Event *de)
131 count = SimpleTimingPort->drain(de);
133 changeState(Draining);
135 changeState(Drained);
140 unsigned int drain(Event *de);
143 #endif // __MEM_TPORT_HH__