src/mem/packet.hh

   1 /*
   2  * Copyright (c) 2006 The Regents of The University of Michigan
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions are
   7  * met: redistributions of source code must retain the above copyright
   8  * notice, this list of conditions and the following disclaimer;
   9  * redistributions in binary form must reproduce the above copyright
  10  * notice, this list of conditions and the following disclaimer in the
  11  * documentation and/or other materials provided with the distribution;
  12  * neither the name of the copyright holders nor the names of its
  13  * contributors may be used to endorse or promote products derived from
  14  * this software without specific prior written permission.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  17  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  18  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  19  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  20  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  21  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  22  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  26  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27  */
  28
  29 /**
  30  * @file
  31  * Declaration of the Packet class.
  32  */
  33
  34 #ifndef __MEM_PACKET_HH__
  35 #define __MEM_PACKET_HH__
  36
  37 #include "mem/request.hh"
  38 #include "arch/isa_traits.hh"
  39 #include "sim/root.hh"
  40
  41 struct Packet;
  42 typedef Packet* PacketPtr;
  43 typedef uint8_t* PacketDataPtr;
  44
  45 /**
  46  * A Packet is used to encapsulate a transfer between two objects in
  47  * the memory system (e.g., the L1 and L2 cache).  (In contrast, a
  48  * single Request travels all the way from the requester to the
  49  * ultimate destination and back, possibly being conveyed by several
  50  * different Packets along the way.)
  51  */
  52 class Packet
  53 {
  54   private:
  55    /** A pointer to the data being transfered.  It can be differnt
  56     *    sizes at each level of the heirarchy so it belongs in the
  57     *    packet, not request. This may or may not be populated when a
  58     *    responder recieves the packet. If not populated it memory
  59     *    should be allocated.
  60     */
  61     PacketDataPtr data;
  62
  63     /** Is the data pointer set to a value that shouldn't be freed
  64      *   when the packet is destroyed? */
  65     bool staticData;
  66     /** The data pointer points to a value that should be freed when
  67      *   the packet is destroyed. */
  68     bool dynamicData;
  69     /** the data pointer points to an array (thus delete [] ) needs to
  70      *   be called on it rather than simply delete.*/
  71     bool arrayData;
  72
  73
  74     /** The address of the request.  This address could be virtual or
  75      *   physical, depending on the system configuration. */
  76     Addr addr;
  77
  78      /** The size of the request or transfer. */
  79     int size;
  80
  81     /** Device address (e.g., bus ID) of the source of the
  82      *   transaction. The source is not responsible for setting this
  83      *   field; it is set implicitly by the interconnect when the
  84      *   packet * is first sent.  */
  85     short src;
  86
  87     /** Device address (e.g., bus ID) of the destination of the
  88      *   transaction. The special value Broadcast indicates that the
  89      *   packet should be routed based on its address. This field is
  90      *   initialized in the constructor and is thus always valid
  91      *   (unlike * addr, size, and src). */
  92     short dest;
  93
  94     /** Is the 'addr' field valid? */
  95     bool addrValid;
  96     /** Is the 'size' field valid? */
  97     bool sizeValid;
  98     /** Is the 'src' field valid? */
  99     bool srcValid;
 100
 101   public:
 102
 103     /** The special destination address indicating that the packet
 104      *   should be routed based on its address. */
 105     static const short Broadcast = -1;
 106
 107     /** A pointer to the original request. */
 108     RequestPtr req;
 109
 110     /** A virtual base opaque structure used to hold coherence-related
 111      *    state.  A specific subclass would be derived from this to
 112      *    carry state specific to a particular coherence protocol.  */
 113     class CoherenceState {
 114       public:
 115         virtual ~CoherenceState() {}
 116     };
 117
 118     /** This packet's coherence state.  Caches should use
 119      *   dynamic_cast<> to cast to the state appropriate for the
 120      *   system's coherence protocol.  */
 121     CoherenceState *coherence;
 122
 123     /** A virtual base opaque structure used to hold state associated
 124      *    with the packet but specific to the sending device (e.g., an
 125      *    MSHR).  A pointer to this state is returned in the packet's
 126      *    response so that the sender can quickly look up the state
 127      *    needed to process it.  A specific subclass would be derived
 128      *    from this to carry state specific to a particular sending
 129      *    device.  */
 130     class SenderState {
 131       public:
 132         virtual ~SenderState() {}
 133     };
 134
 135     /** This packet's sender state.  Devices should use dynamic_cast<>
 136      *   to cast to the state appropriate to the sender. */
 137     SenderState *senderState;
 138
 139   private:
 140     /** List of command attributes. */
 141     enum CommandAttribute
 142     {
 143         IsRead          = 1 << 0,
 144         IsWrite         = 1 << 1,
 145         IsPrefetch      = 1 << 2,
 146         IsInvalidate    = 1 << 3,
 147         IsRequest       = 1 << 4,
 148         IsResponse      = 1 << 5,
 149         NeedsResponse   = 1 << 6,
 150     };
 151
 152   public:
 153     /** List of all commands associated with a packet. */
 154     enum Command
 155     {
 156         ReadReq         = IsRead  | IsRequest | NeedsResponse,
 157         WriteReq        = IsWrite | IsRequest | NeedsResponse,
 158         WriteReqNoAck   = IsWrite | IsRequest,
 159         ReadResp        = IsRead  | IsResponse,
 160         WriteResp       = IsWrite | IsResponse
 161     };
 162
 163     /** Return the string name of the cmd field (for debugging and
 164      *   tracing). */
 165     const std::string &cmdString() const;
 166
 167     /** The command field of the packet. */
 168     Command cmd;
 169
 170     bool isRead()        { return (cmd & IsRead)  != 0; }
 171     bool isRequest()     { return (cmd & IsRequest)  != 0; }
 172     bool isResponse()    { return (cmd & IsResponse) != 0; }
 173     bool needsResponse() { return (cmd & NeedsResponse) != 0; }
 174
 175     /** Possible results of a packet's request. */
 176     enum Result
 177     {
 178         Success,
 179         BadAddress,
 180         Unknown
 181     };
 182
 183     /** The result of this packet's request. */
 184     Result result;
 185
 186     /** Accessor function that returns the source index of the packet. */
 187     short getSrc() const { assert(srcValid); return src; }
 188     void setSrc(short _src) { src = _src; srcValid = true; }
 189
 190     /** Accessor function that returns the destination index of
 191         the packet. */
 192     short getDest() const { return dest; }
 193     void setDest(short _dest) { dest = _dest; }
 194
 195     Addr getAddr() const { assert(addrValid); return addr; }
 196     void setAddr(Addr _addr) { addr = _addr; addrValid = true; }
 197
 198     int getSize() const { assert(sizeValid); return size; }
 199     void setSize(int _size) { size = _size; sizeValid = true; }
 200
 201     /** Constructor.  Note that a Request object must be constructed
 202      *   first, but the Requests's physical address and size fields
 203      *   need not be valid. The command and destination addresses
 204      *   must be supplied.  */
 205     Packet(Request *_req, Command _cmd, short _dest)
 206         :  data(NULL), staticData(false), dynamicData(false), arrayData(false),
 207            addr(_req->paddr), size(_req->size), dest(_dest),
 208            addrValid(_req->validPaddr), sizeValid(_req->validSize),
 209            srcValid(false),
 210            req(_req), coherence(NULL), senderState(NULL), cmd(_cmd),
 211            result(Unknown)
 212     {
 213     }
 214
 215     /** Destructor. */
 216     ~Packet()
 217     { deleteData(); }
 218
 219     /** Reinitialize packet address and size from the associated
 220      *   Request object, and reset other fields that may have been
 221      *   modified by a previous transaction.  Typically called when a
 222      *   statically allocated Request/Packet pair is reused for
 223      *   multiple transactions. */
 224     void reinitFromRequest() {
 225         assert(req->validPaddr);
 226         setAddr(req->paddr);
 227         assert(req->validSize);
 228         setSize(req->size);
 229         result = Unknown;
 230         if (dynamicData) {
 231             deleteData();
 232             dynamicData = false;
 233             arrayData = false;
 234         }
 235     }
 236
 237     /** Take a request packet and modify it in place to be suitable
 238      *   for returning as a response to that request.  Used for timing
 239      *   accesses only.  For atomic and functional accesses, the
 240      *   request packet is always implicitly passed back *without*
 241      *   modifying the command or destination fields, so this function
 242      *   should not be called. */
 243     void makeTimingResponse() {
 244         assert(needsResponse());
 245         int icmd = (int)cmd;
 246         icmd &= ~(IsRequest | NeedsResponse);
 247         icmd |= IsResponse;
 248         cmd = (Command)icmd;
 249         dest = src;
 250         srcValid = false;
 251     }
 252
 253     /** Set the data pointer to the following value that should not be freed. */
 254     template <typename T>
 255     void dataStatic(T *p);
 256
 257     /** Set the data pointer to a value that should have delete [] called on it.
 258      */
 259     template <typename T>
 260     void dataDynamicArray(T *p);
 261
 262     /** set the data pointer to a value that should have delete called on it. */
 263     template <typename T>
 264     void dataDynamic(T *p);
 265
 266     /** return the value of what is pointed to in the packet. */
 267     template <typename T>
 268     T get();
 269
 270     /** get a pointer to the data ptr. */
 271     template <typename T>
 272     T* getPtr();
 273
 274     /** set the value in the data pointer to v. */
 275     template <typename T>
 276     void set(T v);
 277
 278     /** delete the data pointed to in the data pointer. Ok to call to matter how
 279      * data was allocted. */
 280     void deleteData();
 281
 282     /** If there isn't data in the packet, allocate some. */
 283     void allocate();
 284
 285     /** Do the packet modify the same addresses. */
 286     bool intersect(Packet *p);
 287 };
 288
 289 bool fixPacket(Packet *func, Packet *timing);
 290 #endif //__MEM_PACKET_HH