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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 deferred packet, buffered to transmit later. */
62 class DeferredPacket {
64 Tick tick; ///< The tick when the packet is ready to transmit
65 PacketPtr pkt; ///< Pointer to the packet to transmit
66 DeferredPacket(Tick t, PacketPtr p)
71 typedef std::list<DeferredPacket> DeferredPacketList;
72 typedef std::list<DeferredPacket>::iterator DeferredPacketIterator;
74 /** A list of outgoing timing response packets that haven't been
76 DeferredPacketList transmitList;
78 /** This function attempts to send deferred packets. Scheduled to
79 * be called in the future via SendEvent. */
80 void processSendEvent();
83 * This class is used to implemented sendTiming() with a delay. When
84 * a delay is requested a the event is scheduled if it isn't already.
85 * When the event time expires it attempts to send the packet.
86 * If it cannot, the packet sent when recvRetry() is called.
88 typedef EventWrapper<SimpleTimingPort, &SimpleTimingPort::processSendEvent>
93 /** If we need to drain, keep the drain event around until we're done
97 /** Check the list of buffered packets against the supplied
98 * functional request. */
99 void checkFunctional(PacketPtr funcPkt);
101 /** Schedule a sendTiming() event to be called in the future.
102 * @param pkt packet to send
103 * @param time increment from now (in ticks) to send packet
105 void sendTiming(PacketPtr pkt, Tick time);
107 /** This function is notification that the device should attempt to send a
109 virtual void recvRetry();
111 /** Implemented using recvAtomic(). */
112 void recvFunctional(PacketPtr pkt);
114 /** Implemented using recvAtomic(). */
115 bool recvTiming(PacketPtr pkt);
118 * Simple ports generally don't care about any status
119 * changes... can always override this in cases where that's not
121 virtual void recvStatusChange(Status status) { }
126 SimpleTimingPort(std::string pname, MemObject *_owner = NULL)
127 : Port(pname, _owner),
128 sendEvent(new SendEvent(this)),
132 ~SimpleTimingPort() { delete sendEvent; }
134 /** Hook for draining timing accesses from the system. The
135 * associated SimObject's drain() functions should be implemented
136 * something like this when this class is used:
138 PioDevice::drain(Event *de)
141 count = SimpleTimingPort->drain(de);
143 changeState(Draining);
145 changeState(Drained);
150 unsigned int drain(Event *de);
153 #endif // __MEM_TPORT_HH__