summaryrefslogtreecommitdiff
path: root/src/mem/packet.hh
blob: 8badc7c73cca14111108f25f1f94add5894cfd24 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
/*
 * Copyright (c) 2012-2015 ARM Limited
 * All rights reserved
 *
 * The license below extends only to copyright in the software and shall
 * not be construed as granting a license to any other intellectual
 * property including but not limited to intellectual property relating
 * to a hardware implementation of the functionality of the software
 * licensed hereunder.  You may use the software subject to the license
 * terms below provided that you ensure that this notice is replicated
 * unmodified and in its entirety in all distributions of the software,
 * modified or unmodified, in source code or in binary form.
 *
 * Copyright (c) 2006 The Regents of The University of Michigan
 * Copyright (c) 2010 Advanced Micro Devices, Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met: redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer;
 * redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution;
 * neither the name of the copyright holders nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Authors: Ron Dreslinski
 *          Steve Reinhardt
 *          Ali Saidi
 *          Andreas Hansson
 */

/**
 * @file
 * Declaration of the Packet class.
 */

#ifndef __MEM_PACKET_HH__
#define __MEM_PACKET_HH__

#include <bitset>
#include <cassert>
#include <list>

#include "base/cast.hh"
#include "base/compiler.hh"
#include "base/flags.hh"
#include "base/misc.hh"
#include "base/printable.hh"
#include "base/types.hh"
#include "mem/request.hh"
#include "sim/core.hh"

class Packet;
typedef Packet *PacketPtr;
typedef uint8_t* PacketDataPtr;
typedef std::list<PacketPtr> PacketList;

class MemCmd
{
    friend class Packet;

  public:
    /**
     * List of all commands associated with a packet.
     */
    enum Command
    {
        InvalidCmd,
        ReadReq,
        ReadResp,
        ReadRespWithInvalidate,
        WriteReq,
        WriteResp,
        Writeback,
        SoftPFReq,
        HardPFReq,
        SoftPFResp,
        HardPFResp,
        WriteInvalidateReq,
        WriteInvalidateResp,
        UpgradeReq,
        SCUpgradeReq,           // Special "weak" upgrade for StoreCond
        UpgradeResp,
        SCUpgradeFailReq,       // Failed SCUpgradeReq in MSHR (never sent)
        UpgradeFailResp,        // Valid for SCUpgradeReq only
        ReadExReq,
        ReadExResp,
        LoadLockedReq,
        StoreCondReq,
        StoreCondFailReq,       // Failed StoreCondReq in MSHR (never sent)
        StoreCondResp,
        SwapReq,
        SwapResp,
        MessageReq,
        MessageResp,
        // Error responses
        // @TODO these should be classified as responses rather than
        // requests; coding them as requests initially for backwards
        // compatibility
        InvalidDestError,  // packet dest field invalid
        BadAddressError,   // memory address invalid
        FunctionalReadError, // unable to fulfill functional read
        FunctionalWriteError, // unable to fulfill functional write
        // Fake simulator-only commands
        PrintReq,       // Print state matching address
        FlushReq,      //request for a cache flush
        InvalidationReq,   // request for address to be invalidated from lsq
        NUM_MEM_CMDS
    };

  private:
    /**
     * List of command attributes.
     */
    enum Attribute
    {
        IsRead,         //!< Data flows from responder to requester
        IsWrite,        //!< Data flows from requester to responder
        IsUpgrade,
        IsInvalidate,
        NeedsExclusive, //!< Requires exclusive copy to complete in-cache
        IsRequest,      //!< Issued by requester
        IsResponse,     //!< Issue by responder
        NeedsResponse,  //!< Requester needs response from target
        IsSWPrefetch,
        IsHWPrefetch,
        IsLlsc,         //!< Alpha/MIPS LL or SC access
        HasData,        //!< There is an associated payload
        IsError,        //!< Error response
        IsPrint,        //!< Print state matching address (for debugging)
        IsFlush,        //!< Flush the address from caches
        NUM_COMMAND_ATTRIBUTES
    };

    /**
     * Structure that defines attributes and other data associated
     * with a Command.
     */
    struct CommandInfo
    {
        /// Set of attribute flags.
        const std::bitset<NUM_COMMAND_ATTRIBUTES> attributes;
        /// Corresponding response for requests; InvalidCmd if no
        /// response is applicable.
        const Command response;
        /// String representation (for printing)
        const std::string str;
    };

    /// Array to map Command enum to associated info.
    static const CommandInfo commandInfo[];

  private:

    Command cmd;

    bool
    testCmdAttrib(MemCmd::Attribute attrib) const
    {
        return commandInfo[cmd].attributes[attrib] != 0;
    }

  public:

    bool isRead() const            { return testCmdAttrib(IsRead); }
    bool isWrite() const           { return testCmdAttrib(IsWrite); }
    bool isUpgrade() const         { return testCmdAttrib(IsUpgrade); }
    bool isRequest() const         { return testCmdAttrib(IsRequest); }
    bool isResponse() const        { return testCmdAttrib(IsResponse); }
    bool needsExclusive() const    { return testCmdAttrib(NeedsExclusive); }
    bool needsResponse() const     { return testCmdAttrib(NeedsResponse); }
    bool isInvalidate() const      { return testCmdAttrib(IsInvalidate); }
    bool isWriteInvalidate() const { return testCmdAttrib(IsWrite) &&
                                            testCmdAttrib(IsInvalidate); }

    /**
     * Check if this particular packet type carries payload data. Note
     * that this does not reflect if the data pointer of the packet is
     * valid or not.
     */
    bool hasData() const        { return testCmdAttrib(HasData); }
    bool isLLSC() const         { return testCmdAttrib(IsLlsc); }
    bool isSWPrefetch() const   { return testCmdAttrib(IsSWPrefetch); }
    bool isHWPrefetch() const   { return testCmdAttrib(IsHWPrefetch); }
    bool isPrefetch() const     { return testCmdAttrib(IsSWPrefetch) ||
                                         testCmdAttrib(IsHWPrefetch); }
    bool isError() const        { return testCmdAttrib(IsError); }
    bool isPrint() const        { return testCmdAttrib(IsPrint); }
    bool isFlush() const        { return testCmdAttrib(IsFlush); }

    const Command
    responseCommand() const
    {
        return commandInfo[cmd].response;
    }

    /// Return the string to a cmd given by idx.
    const std::string &toString() const { return commandInfo[cmd].str; }
    int toInt() const { return (int)cmd; }

    MemCmd(Command _cmd) : cmd(_cmd) { }
    MemCmd(int _cmd) : cmd((Command)_cmd) { }
    MemCmd() : cmd(InvalidCmd) { }

    bool operator==(MemCmd c2) const { return (cmd == c2.cmd); }
    bool operator!=(MemCmd c2) const { return (cmd != c2.cmd); }
};

/**
 * A Packet is used to encapsulate a transfer between two objects in
 * the memory system (e.g., the L1 and L2 cache).  (In contrast, a
 * single Request travels all the way from the requester to the
 * ultimate destination and back, possibly being conveyed by several
 * different Packets along the way.)
 */
class Packet : public Printable
{
  public:
    typedef uint32_t FlagsType;
    typedef ::Flags<FlagsType> Flags;

  private:
    static const FlagsType PUBLIC_FLAGS           = 0x00000000;
    static const FlagsType PRIVATE_FLAGS          = 0x00007F0F;
    static const FlagsType COPY_FLAGS             = 0x0000000F;

    static const FlagsType SHARED                 = 0x00000001;
    // Special control flags
    /// Special timing-mode atomic snoop for multi-level coherence.
    static const FlagsType EXPRESS_SNOOP          = 0x00000002;
    /// Does supplier have exclusive copy?
    /// Useful for multi-level coherence.
    static const FlagsType SUPPLY_EXCLUSIVE       = 0x00000004;
    // Snoop response flags
    static const FlagsType MEM_INHIBIT            = 0x00000008;
    /// Are the 'addr' and 'size' fields valid?
    static const FlagsType VALID_ADDR             = 0x00000100;
    static const FlagsType VALID_SIZE             = 0x00000200;
    /// Is the data pointer set to a value that shouldn't be freed
    /// when the packet is destroyed?
    static const FlagsType STATIC_DATA            = 0x00001000;
    /// The data pointer points to a value that should be freed when
    /// the packet is destroyed. The pointer is assumed to be pointing
    /// to an array, and delete [] is consequently called
    static const FlagsType DYNAMIC_DATA           = 0x00002000;
    /// suppress the error if this packet encounters a functional
    /// access failure.
    static const FlagsType SUPPRESS_FUNC_ERROR    = 0x00008000;
    // Signal prefetch squash through express snoop flag
    static const FlagsType PREFETCH_SNOOP_SQUASH  = 0x00010000;

    Flags flags;

  public:
    typedef MemCmd::Command Command;

    /// The command field of the packet.
    MemCmd cmd;

    /// A pointer to the original request.
    const RequestPtr req;

  private:
   /**
    * A pointer to the data being transfered.  It can be differnt
    * sizes at each level of the heirarchy so it belongs in the
    * packet, not request. This may or may not be populated when a
    * responder recieves the packet. If not populated it memory should
    * be allocated.
    */
    PacketDataPtr data;

    /// The address of the request.  This address could be virtual or
    /// physical, depending on the system configuration.
    Addr addr;

    /// True if the request targets the secure memory space.
    bool _isSecure;

    /// The size of the request or transfer.
    unsigned size;

    /**
     * The original value of the command field.  Only valid when the
     * current command field is an error condition; in that case, the
     * previous contents of the command field are copied here.  This
     * field is *not* set on non-error responses.
     */
    MemCmd origCmd;

    /**
     * Track the bytes found that satisfy a functional read.
     */
    std::vector<bool> bytesValid;

  public:

    /**
     * The extra delay from seeing the packet until the header is
     * transmitted. This delay is used to communicate the crossbar
     * forwarding latency to the neighbouring object (e.g. a cache)
     * that actually makes the packet wait. As the delay is relative,
     * a 32-bit unsigned should be sufficient.
     */
    uint32_t headerDelay;

    /**
     * The extra pipelining delay from seeing the packet until the end of
     * payload is transmitted by the component that provided it (if
     * any). This includes the header delay. Similar to the header
     * delay, this is used to make up for the fact that the
     * crossbar does not make the packet wait. As the delay is
     * relative, a 32-bit unsigned should be sufficient.
     */
    uint32_t payloadDelay;

    /**
     * A virtual base opaque structure used to hold state associated
     * with the packet (e.g., an MSHR), specific to a MemObject that
     * sees the packet. A pointer to this state is returned in the
     * packet's response so that the MemObject in question can quickly
     * look up the state needed to process it. A specific subclass
     * would be derived from this to carry state specific to a
     * particular sending device.
     *
     * As multiple MemObjects may add their SenderState throughout the
     * memory system, the SenderStates create a stack, where a
     * MemObject can add a new Senderstate, as long as the
     * predecessing SenderState is restored when the response comes
     * back. For this reason, the predecessor should always be
     * populated with the current SenderState of a packet before
     * modifying the senderState field in the request packet.
     */
    struct SenderState
    {
        SenderState* predecessor;
        SenderState() : predecessor(NULL) {}
        virtual ~SenderState() {}
    };

    /**
     * Object used to maintain state of a PrintReq.  The senderState
     * field of a PrintReq should always be of this type.
     */
    class PrintReqState : public SenderState
    {
      private:
        /**
         * An entry in the label stack.
         */
        struct LabelStackEntry
        {
            const std::string label;
            std::string *prefix;
            bool labelPrinted;
            LabelStackEntry(const std::string &_label, std::string *_prefix);
        };

        typedef std::list<LabelStackEntry> LabelStack;
        LabelStack labelStack;

        std::string *curPrefixPtr;

      public:
        std::ostream &os;
        const int verbosity;

        PrintReqState(std::ostream &os, int verbosity = 0);
        ~PrintReqState();

        /**
         * Returns the current line prefix.
         */
        const std::string &curPrefix() { return *curPrefixPtr; }

        /**
         * Push a label onto the label stack, and prepend the given
         * prefix string onto the current prefix.  Labels will only be
         * printed if an object within the label's scope is printed.
         */
        void pushLabel(const std::string &lbl,
                       const std::string &prefix = "  ");

        /**
         * Pop a label off the label stack.
         */
        void popLabel();

        /**
         * Print all of the pending unprinted labels on the
         * stack. Called by printObj(), so normally not called by
         * users unless bypassing printObj().
         */
        void printLabels();

        /**
         * Print a Printable object to os, because it matched the
         * address on a PrintReq.
         */
        void printObj(Printable *obj);
    };

    /**
     * This packet's sender state.  Devices should use dynamic_cast<>
     * to cast to the state appropriate to the sender.  The intent of
     * this variable is to allow a device to attach extra information
     * to a request. A response packet must return the sender state
     * that was attached to the original request (even if a new packet
     * is created).
     */
    SenderState *senderState;

    /**
     * Push a new sender state to the packet and make the current
     * sender state the predecessor of the new one. This should be
     * prefered over direct manipulation of the senderState member
     * variable.
     *
     * @param sender_state SenderState to push at the top of the stack
     */
    void pushSenderState(SenderState *sender_state);

    /**
     * Pop the top of the state stack and return a pointer to it. This
     * assumes the current sender state is not NULL. This should be
     * preferred over direct manipulation of the senderState member
     * variable.
     *
     * @return The current top of the stack
     */
    SenderState *popSenderState();

    /**
     * Go through the sender state stack and return the first instance
     * that is of type T (as determined by a dynamic_cast). If there
     * is no sender state of type T, NULL is returned.
     *
     * @return The topmost state of type T
     */
    template <typename T>
    T * findNextSenderState() const
    {
        T *t = NULL;
        SenderState* sender_state = senderState;
        while (t == NULL && sender_state != NULL) {
            t = dynamic_cast<T*>(sender_state);
            sender_state = sender_state->predecessor;
        }
        return t;
    }

    /// Return the string name of the cmd field (for debugging and
    /// tracing).
    const std::string &cmdString() const { return cmd.toString(); }

    /// Return the index of this command.
    inline int cmdToIndex() const { return cmd.toInt(); }

    bool isRead() const              { return cmd.isRead(); }
    bool isWrite() const             { return cmd.isWrite(); }
    bool isUpgrade()  const          { return cmd.isUpgrade(); }
    bool isRequest() const           { return cmd.isRequest(); }
    bool isResponse() const          { return cmd.isResponse(); }
    bool needsExclusive() const      { return cmd.needsExclusive(); }
    bool needsResponse() const       { return cmd.needsResponse(); }
    bool isInvalidate() const        { return cmd.isInvalidate(); }
    bool isWriteInvalidate() const   { return cmd.isWriteInvalidate(); }
    bool hasData() const             { return cmd.hasData(); }
    bool isLLSC() const              { return cmd.isLLSC(); }
    bool isError() const             { return cmd.isError(); }
    bool isPrint() const             { return cmd.isPrint(); }
    bool isFlush() const             { return cmd.isFlush(); }

    // Snoop flags
    void assertMemInhibit()
    {
        assert(isRequest());
        assert(!flags.isSet(MEM_INHIBIT));
        flags.set(MEM_INHIBIT);
    }
    bool memInhibitAsserted() const { return flags.isSet(MEM_INHIBIT); }
    void assertShared()             { flags.set(SHARED); }
    bool sharedAsserted() const     { return flags.isSet(SHARED); }

    // Special control flags
    void setExpressSnoop()          { flags.set(EXPRESS_SNOOP); }
    bool isExpressSnoop() const     { return flags.isSet(EXPRESS_SNOOP); }
    void setSupplyExclusive()       { flags.set(SUPPLY_EXCLUSIVE); }
    void clearSupplyExclusive()     { flags.clear(SUPPLY_EXCLUSIVE); }
    bool isSupplyExclusive() const  { return flags.isSet(SUPPLY_EXCLUSIVE); }
    void setSuppressFuncError()     { flags.set(SUPPRESS_FUNC_ERROR); }
    bool suppressFuncError() const  { return flags.isSet(SUPPRESS_FUNC_ERROR); }
    void setPrefetchSquashed()      { flags.set(PREFETCH_SNOOP_SQUASH); }
    bool prefetchSquashed() const   { return flags.isSet(PREFETCH_SNOOP_SQUASH); }

    // Network error conditions... encapsulate them as methods since
    // their encoding keeps changing (from result field to command
    // field, etc.)
    void
    setBadAddress()
    {
        assert(isResponse());
        cmd = MemCmd::BadAddressError;
    }

    bool hadBadAddress() const { return cmd == MemCmd::BadAddressError; }
    void copyError(Packet *pkt) { assert(pkt->isError()); cmd = pkt->cmd; }

    Addr getAddr() const { assert(flags.isSet(VALID_ADDR)); return addr; }
    /**
     * Update the address of this packet mid-transaction. This is used
     * by the address mapper to change an already set address to a new
     * one based on the system configuration. It is intended to remap
     * an existing address, so it asserts that the current address is
     * valid.
     */
    void setAddr(Addr _addr) { assert(flags.isSet(VALID_ADDR)); addr = _addr; }

    unsigned getSize() const  { assert(flags.isSet(VALID_SIZE)); return size; }
    Addr getOffset(int blkSize) const { return getAddr() & (Addr)(blkSize - 1); }

    bool isSecure() const
    {
        assert(flags.isSet(VALID_ADDR));
        return _isSecure;
    }

    /**
     * It has been determined that the SC packet should successfully update
     * memory.  Therefore, convert this SC packet to a normal write.
     */
    void
    convertScToWrite()
    {
        assert(isLLSC());
        assert(isWrite());
        cmd = MemCmd::WriteReq;
    }

    /**
     * When ruby is in use, Ruby will monitor the cache line and thus M5 
     * phys memory should treat LL ops as normal reads. 
     */
    void
    convertLlToRead()
    {
        assert(isLLSC());
        assert(isRead());
        cmd = MemCmd::ReadReq;
    }

    /**
     * Constructor.  Note that a Request object must be constructed
     * first, but the Requests's physical address and size fields need
     * not be valid. The command must be supplied.
     */
    Packet(const RequestPtr _req, MemCmd _cmd)
        :  cmd(_cmd), req(_req), data(nullptr), addr(0), _isSecure(false),
           size(0), headerDelay(0), payloadDelay(0),
           senderState(NULL)
    {
        if (req->hasPaddr()) {
            addr = req->getPaddr();
            flags.set(VALID_ADDR);
            _isSecure = req->isSecure();
        }
        if (req->hasSize()) {
            size = req->getSize();
            flags.set(VALID_SIZE);
        }
    }

    /**
     * Alternate constructor if you are trying to create a packet with
     * a request that is for a whole block, not the address from the
     * req.  this allows for overriding the size/addr of the req.
     */
    Packet(const RequestPtr _req, MemCmd _cmd, int _blkSize)
        :  cmd(_cmd), req(_req), data(nullptr), addr(0), _isSecure(false),
           headerDelay(0), payloadDelay(0),
           senderState(NULL)
    {
        if (req->hasPaddr()) {
            addr = req->getPaddr() & ~(_blkSize - 1);
            flags.set(VALID_ADDR);
            _isSecure = req->isSecure();
        }
        size = _blkSize;
        flags.set(VALID_SIZE);
    }

    /**
     * Alternate constructor for copying a packet.  Copy all fields
     * *except* if the original packet's data was dynamic, don't copy
     * that, as we can't guarantee that the new packet's lifetime is
     * less than that of the original packet.  In this case the new
     * packet should allocate its own data.
     */
    Packet(PacketPtr pkt, bool clear_flags, bool alloc_data)
        :  cmd(pkt->cmd), req(pkt->req),
           data(nullptr),
           addr(pkt->addr), _isSecure(pkt->_isSecure), size(pkt->size),
           bytesValid(pkt->bytesValid),
           headerDelay(pkt->headerDelay),
           payloadDelay(pkt->payloadDelay),
           senderState(pkt->senderState)
    {
        if (!clear_flags)
            flags.set(pkt->flags & COPY_FLAGS);

        flags.set(pkt->flags & (VALID_ADDR|VALID_SIZE));

        // should we allocate space for data, or not, the express
        // snoops do not need to carry any data as they only serve to
        // co-ordinate state changes
        if (alloc_data) {
            // even if asked to allocate data, if the original packet
            // holds static data, then the sender will not be doing
            // any memcpy on receiving the response, thus we simply
            // carry the pointer forward
            if (pkt->flags.isSet(STATIC_DATA)) {
                data = pkt->data;
                flags.set(STATIC_DATA);
            } else {
                allocate();
            }
        }
    }

    /**
     * Generate the appropriate read MemCmd based on the Request flags.
     */
    static MemCmd
    makeReadCmd(const RequestPtr req)
    {
        if (req->isLLSC())
            return MemCmd::LoadLockedReq;
        else if (req->isPrefetch())
            return MemCmd::SoftPFReq;
        else
            return MemCmd::ReadReq;
    }

    /**
     * Generate the appropriate write MemCmd based on the Request flags.
     */
    static MemCmd
    makeWriteCmd(const RequestPtr req)
    {
        if (req->isLLSC())
            return MemCmd::StoreCondReq;
        else if (req->isSwap())
            return MemCmd::SwapReq;
        else
            return MemCmd::WriteReq;
    }

    /**
     * Constructor-like methods that return Packets based on Request objects.
     * Fine-tune the MemCmd type if it's not a vanilla read or write.
     */
    static PacketPtr
    createRead(const RequestPtr req)
    {
        return new Packet(req, makeReadCmd(req));
    }

    static PacketPtr
    createWrite(const RequestPtr req)
    {
        return new Packet(req, makeWriteCmd(req));
    }

    /**
     * clean up packet variables
     */
    ~Packet()
    {
        // If this is a request packet for which there's no response,
        // delete the request object here, since the requester will
        // never get the chance.
        if (req && isRequest() && !needsResponse())
            delete req;
        deleteData();
    }

    /**
     * Take a request packet and modify it in place to be suitable for
     * returning as a response to that request.
     */
    void
    makeResponse()
    {
        assert(needsResponse());
        assert(isRequest());
        origCmd = cmd;
        cmd = cmd.responseCommand();

        // responses are never express, even if the snoop that
        // triggered them was
        flags.clear(EXPRESS_SNOOP);
    }

    void
    makeAtomicResponse()
    {
        makeResponse();
    }

    void
    makeTimingResponse()
    {
        makeResponse();
    }

    void
    setFunctionalResponseStatus(bool success)
    {
        if (!success) {
            if (isWrite()) {
                cmd = MemCmd::FunctionalWriteError;
            } else {
                cmd = MemCmd::FunctionalReadError;
            }
        }
    }

    void
    setSize(unsigned size)
    {
        assert(!flags.isSet(VALID_SIZE));

        this->size = size;
        flags.set(VALID_SIZE);
    }


    /**
     * Set the data pointer to the following value that should not be
     * freed. Static data allows us to do a single memcpy even if
     * multiple packets are required to get from source to destination
     * and back. In essence the pointer is set calling dataStatic on
     * the original packet, and whenever this packet is copied and
     * forwarded the same pointer is passed on. When a packet
     * eventually reaches the destination holding the data, it is
     * copied once into the location originally set. On the way back
     * to the source, no copies are necessary.
     */
    template <typename T>
    void
    dataStatic(T *p)
    {
        assert(flags.noneSet(STATIC_DATA|DYNAMIC_DATA));
        data = (PacketDataPtr)p;
        flags.set(STATIC_DATA);
    }

    /**
     * Set the data pointer to the following value that should not be
     * freed. This version of the function allows the pointer passed
     * to us to be const. To avoid issues down the line we cast the
     * constness away, the alternative would be to keep both a const
     * and non-const data pointer and cleverly choose between
     * them. Note that this is only allowed for static data.
     */
    template <typename T>
    void
    dataStaticConst(const T *p)
    {
        assert(flags.noneSet(STATIC_DATA|DYNAMIC_DATA));
        data = const_cast<PacketDataPtr>(p);
        flags.set(STATIC_DATA);
    }

    /**
     * Set the data pointer to a value that should have delete []
     * called on it. Dynamic data is local to this packet, and as the
     * packet travels from source to destination, forwarded packets
     * will allocate their own data. When a packet reaches the final
     * destination it will populate the dynamic data of that specific
     * packet, and on the way back towards the source, memcpy will be
     * invoked in every step where a new packet was created e.g. in
     * the caches. Ultimately when the response reaches the source a
     * final memcpy is needed to extract the data from the packet
     * before it is deallocated.
     */
    template <typename T>
    void
    dataDynamic(T *p)
    {
        assert(flags.noneSet(STATIC_DATA|DYNAMIC_DATA));
        data = (PacketDataPtr)p;
        flags.set(DYNAMIC_DATA);
    }

    /**
     * get a pointer to the data ptr.
     */
    template <typename T>
    T*
    getPtr()
    {
        assert(flags.isSet(STATIC_DATA|DYNAMIC_DATA));
        return (T*)data;
    }

    template <typename T>
    const T*
    getConstPtr() const
    {
        assert(flags.isSet(STATIC_DATA|DYNAMIC_DATA));
        return (const T*)data;
    }

    /**
     * return the value of what is pointed to in the packet.
     */
    template <typename T>
    T get() const;

    /**
     * set the value in the data pointer to v.
     */
    template <typename T>
    void set(T v);

    /**
     * Copy data into the packet from the provided pointer.
     */
    void
    setData(const uint8_t *p)
    {
        // we should never be copying data onto itself, which means we
        // must idenfity packets with static data, as they carry the
        // same pointer from source to destination and back
        assert(p != getPtr<uint8_t>() || flags.isSet(STATIC_DATA));

        if (p != getPtr<uint8_t>())
            // for packet with allocated dynamic data, we copy data from
            // one to the other, e.g. a forwarded response to a response
            std::memcpy(getPtr<uint8_t>(), p, getSize());
    }

    /**
     * Copy data into the packet from the provided block pointer,
     * which is aligned to the given block size.
     */
    void
    setDataFromBlock(const uint8_t *blk_data, int blkSize)
    {
        setData(blk_data + getOffset(blkSize));
    }

    /**
     * Copy data from the packet to the provided block pointer, which
     * is aligned to the given block size.
     */
    void
    writeData(uint8_t *p) const
    {
        std::memcpy(p, getConstPtr<uint8_t>(), getSize());
    }

    /**
     * Copy data from the packet to the memory at the provided pointer.
     */
    void
    writeDataToBlock(uint8_t *blk_data, int blkSize) const
    {
        writeData(blk_data + getOffset(blkSize));
    }

    /**
     * delete the data pointed to in the data pointer. Ok to call to
     * matter how data was allocted.
     */
    void
    deleteData()
    {
        if (flags.isSet(DYNAMIC_DATA))
            delete [] data;

        flags.clear(STATIC_DATA|DYNAMIC_DATA);
        data = NULL;
    }

    /** Allocate memory for the packet. */
    void
    allocate()
    {
        assert(flags.noneSet(STATIC_DATA|DYNAMIC_DATA));
        flags.set(DYNAMIC_DATA);
        data = new uint8_t[getSize()];
    }

    /**
     * Check a functional request against a memory value stored in
     * another packet (i.e. an in-transit request or
     * response). Returns true if the current packet is a read, and
     * the other packet provides the data, which is then copied to the
     * current packet. If the current packet is a write, and the other
     * packet intersects this one, then we update the data
     * accordingly.
     */
    bool
    checkFunctional(PacketPtr other)
    {
        // all packets that are carrying a payload should have a valid
        // data pointer
        return checkFunctional(other, other->getAddr(), other->isSecure(),
                               other->getSize(),
                               other->hasData() ?
                               other->getPtr<uint8_t>() : NULL);
    }

    /**
     * Check a functional request against a memory value represented
     * by a base/size pair and an associated data array. If the
     * current packet is a read, it may be satisfied by the memory
     * value. If the current packet is a write, it may update the
     * memory value.
     */
    bool
    checkFunctional(Printable *obj, Addr base, bool is_secure, int size,
                    uint8_t *_data);

    /**
     * Push label for PrintReq (safe to call unconditionally).
     */
    void
    pushLabel(const std::string &lbl)
    {
        if (isPrint())
            safe_cast<PrintReqState*>(senderState)->pushLabel(lbl);
    }

    /**
     * Pop label for PrintReq (safe to call unconditionally).
     */
    void
    popLabel()
    {
        if (isPrint())
            safe_cast<PrintReqState*>(senderState)->popLabel();
    }

    void print(std::ostream &o, int verbosity = 0,
               const std::string &prefix = "") const;

    /**
     * A no-args wrapper of print(std::ostream...)
     * meant to be invoked from DPRINTFs
     * avoiding string overheads in fast mode
     * @return string with the request's type and start<->end addresses
     */
    std::string print() const;
};

#endif //__MEM_PACKET_HH