packet.hh revision 2812:8e5feae75615 
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
46struct Packet;
47typedef Packet* PacketPtr;
48typedef uint8_t* PacketDataPtr;
49typedef 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 */
67class 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
334bool fixPacket(Packet *func, Packet *timing);
335#endif //__MEM_PACKET_HH
336