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  * Authors: Ron Dreslinski
  29  *          Steve Reinhardt
  30  *          Ali Saidi
  31  */
  32
  33 /**
  34  * @file
  35  * Declaration of the Packet class.
  36  */
  37
  38 #ifndef __MEM_PACKET_HH__
  39 #define __MEM_PACKET_HH__
  40
  41 #include "mem/request.hh"
  42 #include "arch/isa_traits.hh"
  43 #include "sim/root.hh"
  44 #include <list>
  45
  46 struct Packet;
  47 typedef Packet* PacketPtr;
  48 typedef uint8_t* PacketDataPtr;
  49 typedef std::list<PacketPtr> PacketList;
  50
  51 //Coherence Flags
  52 #define NACKED_LINE 1 << 0
  53 #define SATISFIED 1 << 1
  54 #define SHARED_LINE 1 << 2
  55
  56 //For statistics we need max number of commands, hard code it at
  57 //20 for now.  @todo fix later
  58 #define NUM_MEM_CMDS 1 << 9
  59
  60 /**
  61  * A Packet is used to encapsulate a transfer between two objects in
  62  * the memory system (e.g., the L1 and L2 cache).  (In contrast, a
  63  * single Request travels all the way from the requester to the
  64  * ultimate destination and back, possibly being conveyed by several
  65  * different Packets along the way.)
  66  */
  67 class Packet
  68 {
  69   private:
  70    /** A pointer to the data being transfered.  It can be differnt
  71     *    sizes at each level of the heirarchy so it belongs in the
  72     *    packet, not request. This may or may not be populated when a
  73     *    responder recieves the packet. If not populated it memory
  74     *    should be allocated.
  75     */
  76     PacketDataPtr data;
  77
  78     /** Is the data pointer set to a value that shouldn't be freed
  79      *   when the packet is destroyed? */
  80     bool staticData;
  81     /** The data pointer points to a value that should be freed when
  82      *   the packet is destroyed. */
  83     bool dynamicData;
  84     /** the data pointer points to an array (thus delete [] ) needs to
  85      *   be called on it rather than simply delete.*/
  86     bool arrayData;
  87
  88
  89     /** The address of the request.  This address could be virtual or
  90      *   physical, depending on the system configuration. */
  91     Addr addr;
  92
  93      /** The size of the request or transfer. */
  94     int size;
  95
  96     /** Device address (e.g., bus ID) of the source of the
  97      *   transaction. The source is not responsible for setting this
  98      *   field; it is set implicitly by the interconnect when the
  99      *   packet * is first sent.  */
 100     short src;
 101
 102     /** Device address (e.g., bus ID) of the destination of the
 103      *   transaction. The special value Broadcast indicates that the
 104      *   packet should be routed based on its address. This field is
 105      *   initialized in the constructor and is thus always valid
 106      *   (unlike * addr, size, and src). */
 107     short dest;
 108
 109     /** Are the 'addr' and 'size' fields valid? */
 110     bool addrSizeValid;
 111     /** Is the 'src' field valid? */
 112     bool srcValid;
 113
 114   public:
 115
 116     /** Used to calculate latencies for each packet.*/
 117     Tick time;
 118
 119     /** The special destination address indicating that the packet
 120      *   should be routed based on its address. */
 121     static const short Broadcast = -1;
 122
 123     /** A pointer to the original request. */
 124     RequestPtr req;
 125
 126     /** A virtual base opaque structure used to hold coherence-related
 127      *    state.  A specific subclass would be derived from this to
 128      *    carry state specific to a particular coherence protocol.  */
 129     class CoherenceState {
 130       public:
 131         virtual ~CoherenceState() {}
 132     };
 133
 134     /** This packet's coherence state.  Caches should use
 135      *   dynamic_cast<> to cast to the state appropriate for the
 136      *   system's coherence protocol.  */
 137     CoherenceState *coherence;
 138
 139     /** A virtual base opaque structure used to hold state associated
 140      *    with the packet but specific to the sending device (e.g., an
 141      *    MSHR).  A pointer to this state is returned in the packet's
 142      *    response so that the sender can quickly look up the state
 143      *    needed to process it.  A specific subclass would be derived
 144      *    from this to carry state specific to a particular sending
 145      *    device.  */
 146     class SenderState {
 147       public:
 148         virtual ~SenderState() {}
 149     };
 150
 151     /** This packet's sender state.  Devices should use dynamic_cast<>
 152      *   to cast to the state appropriate to the sender. */
 153     SenderState *senderState;
 154
 155   private:
 156     /** List of command attributes. */
 157     enum CommandAttribute
 158     {
 159         IsRead          = 1 << 0,
 160         IsWrite         = 1 << 1,
 161         IsPrefetch      = 1 << 2,
 162         IsInvalidate    = 1 << 3,
 163         IsRequest       = 1 << 4,
 164         IsResponse      = 1 << 5,
 165         NeedsResponse   = 1 << 6,
 166         IsSWPrefetch    = 1 << 7,
 167         IsHWPrefetch    = 1 << 8
 168     };
 169
 170   public:
 171     /** List of all commands associated with a packet. */
 172     enum Command
 173     {
 174         ReadReq         = IsRead  | IsRequest | NeedsResponse,
 175         WriteReq        = IsWrite | IsRequest | NeedsResponse,
 176         WriteReqNoAck   = IsWrite | IsRequest,
 177         ReadResp        = IsRead  | IsResponse,
 178         WriteResp       = IsWrite | IsResponse,
 179         Writeback       = IsWrite | IsRequest,
 180         SoftPFReq       = IsRead  | IsRequest | IsSWPrefetch | NeedsResponse,
 181         HardPFReq       = IsRead  | IsRequest | IsHWPrefetch | NeedsResponse,
 182         SoftPFResp      = IsRead  | IsRequest | IsSWPrefetch | IsResponse,
 183         HardPFResp      = IsRead  | IsRequest | IsHWPrefetch | IsResponse,
 184         InvalidateReq   = IsInvalidate | IsRequest,
 185         WriteInvalidateReq = IsWrite | IsInvalidate | IsRequest,
 186         UpgradeReq      = IsInvalidate | NeedsResponse
 187     };
 188
 189     /** Return the string name of the cmd field (for debugging and
 190      *   tracing). */
 191     const std::string &cmdString() const;
 192
 193     /** Reutrn the string to a cmd given by idx. */
 194     const std::string &cmdIdxToString(Command idx);
 195
 196     /** Return the index of this command. */
 197     inline int cmdToIndex() const { return (int) cmd; }
 198
 199     /** The command field of the packet. */
 200     Command cmd;
 201
 202     bool isRead()        { return (cmd & IsRead)  != 0; }
 203     bool isWrite()       { return (cmd & IsWrite) != 0; }
 204     bool isRequest()     { return (cmd & IsRequest)  != 0; }
 205     bool isResponse()    { return (cmd & IsResponse) != 0; }
 206     bool needsResponse() { return (cmd & NeedsResponse) != 0; }
 207     bool isInvalidate()  { return (cmd * IsInvalidate) != 0; }
 208
 209     bool isCacheFill() { assert("Unimplemented yet\n" && 0); }
 210     bool isNoAllocate() { assert("Unimplemented yet\n" && 0); }
 211
 212     /** Possible results of a packet's request. */
 213     enum Result
 214     {
 215         Success,
 216         BadAddress,
 217         Nacked,
 218         Unknown
 219     };
 220
 221     /** The result of this packet's request. */
 222     Result result;
 223
 224     /** Accessor function that returns the source index of the packet. */
 225     short getSrc() const { assert(srcValid); return src; }
 226     void setSrc(short _src) { src = _src; srcValid = true; }
 227
 228     /** Accessor function that returns the destination index of
 229         the packet. */
 230     short getDest() const { return dest; }
 231     void setDest(short _dest) { dest = _dest; }
 232
 233     Addr getAddr() const { assert(addrSizeValid); return addr; }
 234     int getSize() const { assert(addrSizeValid); return size; }
 235
 236     /** Constructor.  Note that a Request object must be constructed
 237      *   first, but the Requests's physical address and size fields
 238      *   need not be valid. The command and destination addresses
 239      *   must be supplied.  */
 240     Packet(Request *_req, Command _cmd, short _dest)
 241         :  data(NULL), staticData(false), dynamicData(false), arrayData(false),
 242            addr(_req->paddr), size(_req->size), dest(_dest),
 243            addrSizeValid(_req->validPaddr),
 244            srcValid(false),
 245            req(_req), coherence(NULL), senderState(NULL), cmd(_cmd),
 246            result(Unknown)
 247     {
 248     }
 249
 250     /** Destructor. */
 251     ~Packet()
 252     { deleteData(); }
 253
 254     /** Reinitialize packet address and size from the associated
 255      *   Request object, and reset other fields that may have been
 256      *   modified by a previous transaction.  Typically called when a
 257      *   statically allocated Request/Packet pair is reused for
 258      *   multiple transactions. */
 259     void reinitFromRequest() {
 260         assert(req->validPaddr);
 261         addr = req->paddr;
 262         size = req->size;
 263         addrSizeValid = true;
 264         result = Unknown;
 265         if (dynamicData) {
 266             deleteData();
 267             dynamicData = false;
 268             arrayData = false;
 269         }
 270     }
 271
 272     /** Take a request packet and modify it in place to be suitable
 273      *   for returning as a response to that request.  Used for timing
 274      *   accesses only.  For atomic and functional accesses, the
 275      *   request packet is always implicitly passed back *without*
 276      *   modifying the command or destination fields, so this function
 277      *   should not be called. */
 278     void makeTimingResponse() {
 279         assert(needsResponse());
 280         int icmd = (int)cmd;
 281         icmd &= ~(IsRequest | NeedsResponse);
 282         icmd |= IsResponse;
 283         cmd = (Command)icmd;
 284         dest = src;
 285         srcValid = false;
 286     }
 287
 288     /** Take a request packet that has been returned as NACKED and modify it so
 289      * that it can be sent out again. Only packets that need a response can be
 290      * NACKED, so verify that that is true. */
 291     void reinitNacked() {
 292         assert(needsResponse() && result == Nacked);
 293         dest =  Broadcast;
 294         result = Unknown;
 295     }
 296
 297
 298     /** Set the data pointer to the following value that should not be freed. */
 299     template <typename T>
 300     void dataStatic(T *p);
 301
 302     /** Set the data pointer to a value that should have delete [] called on it.
 303      */
 304     template <typename T>
 305     void dataDynamicArray(T *p);
 306
 307     /** set the data pointer to a value that should have delete called on it. */
 308     template <typename T>
 309     void dataDynamic(T *p);
 310
 311     /** return the value of what is pointed to in the packet. */
 312     template <typename T>
 313     T get();
 314
 315     /** get a pointer to the data ptr. */
 316     template <typename T>
 317     T* getPtr();
 318
 319     /** set the value in the data pointer to v. */
 320     template <typename T>
 321     void set(T v);
 322
 323     /** delete the data pointed to in the data pointer. Ok to call to matter how
 324      * data was allocted. */
 325     void deleteData();
 326
 327     /** If there isn't data in the packet, allocate some. */
 328     void allocate();
 329
 330     /** Do the packet modify the same addresses. */
 331     bool intersect(Packet *p);
 332 };
 333
 334 bool fixPacket(Packet *func, Packet *timing);
 335 #endif //__MEM_PACKET_HH