packet.hh revision 2665:a124942bacb8 
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
45struct Packet;
46typedef Packet* PacketPtr;
47typedef uint8_t* PacketDataPtr;
48
49/**
50 * A Packet is used to encapsulate a transfer between two objects in
51 * the memory system (e.g., the L1 and L2 cache).  (In contrast, a
52 * single Request travels all the way from the requester to the
53 * ultimate destination and back, possibly being conveyed by several
54 * different Packets along the way.)
55 */
56class Packet
57{
58  private:
59   /** A pointer to the data being transfered.  It can be differnt
60    *    sizes at each level of the heirarchy so it belongs in the
61    *    packet, not request. This may or may not be populated when a
62    *    responder recieves the packet. If not populated it memory
63    *    should be allocated.
64    */
65    PacketDataPtr data;
66
67    /** Is the data pointer set to a value that shouldn't be freed
68     *   when the packet is destroyed? */
69    bool staticData;
70    /** The data pointer points to a value that should be freed when
71     *   the packet is destroyed. */
72    bool dynamicData;
73    /** the data pointer points to an array (thus delete [] ) needs to
74     *   be called on it rather than simply delete.*/
75    bool arrayData;
76
77
78    /** The address of the request.  This address could be virtual or
79     *   physical, depending on the system configuration. */
80    Addr addr;
81
82     /** The size of the request or transfer. */
83    int size;
84
85    /** Device address (e.g., bus ID) of the source of the
86     *   transaction. The source is not responsible for setting this
87     *   field; it is set implicitly by the interconnect when the
88     *   packet * is first sent.  */
89    short src;
90
91    /** Device address (e.g., bus ID) of the destination of the
92     *   transaction. The special value Broadcast indicates that the
93     *   packet should be routed based on its address. This field is
94     *   initialized in the constructor and is thus always valid
95     *   (unlike * addr, size, and src). */
96    short dest;
97
98    /** Are the 'addr' and 'size' fields valid? */
99    bool addrSizeValid;
100    /** Is the 'src' field valid? */
101    bool srcValid;
102
103  public:
104
105    /** The special destination address indicating that the packet
106     *   should be routed based on its address. */
107    static const short Broadcast = -1;
108
109    /** A pointer to the original request. */
110    RequestPtr req;
111
112    /** A virtual base opaque structure used to hold coherence-related
113     *    state.  A specific subclass would be derived from this to
114     *    carry state specific to a particular coherence protocol.  */
115    class CoherenceState {
116      public:
117        virtual ~CoherenceState() {}
118    };
119
120    /** This packet's coherence state.  Caches should use
121     *   dynamic_cast<> to cast to the state appropriate for the
122     *   system's coherence protocol.  */
123    CoherenceState *coherence;
124
125    /** A virtual base opaque structure used to hold state associated
126     *    with the packet but specific to the sending device (e.g., an
127     *    MSHR).  A pointer to this state is returned in the packet's
128     *    response so that the sender can quickly look up the state
129     *    needed to process it.  A specific subclass would be derived
130     *    from this to carry state specific to a particular sending
131     *    device.  */
132    class SenderState {
133      public:
134        virtual ~SenderState() {}
135    };
136
137    /** This packet's sender state.  Devices should use dynamic_cast<>
138     *   to cast to the state appropriate to the sender. */
139    SenderState *senderState;
140
141  private:
142    /** List of command attributes. */
143    enum CommandAttribute
144    {
145        IsRead		= 1 << 0,
146        IsWrite		= 1 << 1,
147        IsPrefetch	= 1 << 2,
148        IsInvalidate	= 1 << 3,
149        IsRequest	= 1 << 4,
150        IsResponse 	= 1 << 5,
151        NeedsResponse	= 1 << 6,
152    };
153
154  public:
155    /** List of all commands associated with a packet. */
156    enum Command
157    {
158        ReadReq		= IsRead  | IsRequest | NeedsResponse,
159        WriteReq	= IsWrite | IsRequest | NeedsResponse,
160        WriteReqNoAck	= IsWrite | IsRequest,
161        ReadResp	= IsRead  | IsResponse,
162        WriteResp	= IsWrite | IsResponse
163    };
164
165    /** Return the string name of the cmd field (for debugging and
166     *   tracing). */
167    const std::string &cmdString() const;
168
169    /** The command field of the packet. */
170    Command cmd;
171
172    bool isRead() 	 { return (cmd & IsRead)  != 0; }
173    bool isRequest()	 { return (cmd & IsRequest)  != 0; }
174    bool isResponse()	 { return (cmd & IsResponse) != 0; }
175    bool needsResponse() { return (cmd & NeedsResponse) != 0; }
176
177    /** Possible results of a packet's request. */
178    enum Result
179    {
180        Success,
181        BadAddress,
182        Unknown
183    };
184
185    /** The result of this packet's request. */
186    Result result;
187
188    /** Accessor function that returns the source index of the packet. */
189    short getSrc() const { assert(srcValid); return src; }
190    void setSrc(short _src) { src = _src; srcValid = true; }
191
192    /** Accessor function that returns the destination index of
193        the packet. */
194    short getDest() const { return dest; }
195    void setDest(short _dest) { dest = _dest; }
196
197    Addr getAddr() const { assert(addrSizeValid); return addr; }
198    int getSize() const { assert(addrSizeValid); return size; }
199
200    /** Constructor.  Note that a Request object must be constructed
201     *   first, but the Requests's physical address and size fields
202     *   need not be valid. The command and destination addresses
203     *   must be supplied.  */
204    Packet(Request *_req, Command _cmd, short _dest)
205        :  data(NULL), staticData(false), dynamicData(false), arrayData(false),
206           addr(_req->paddr), size(_req->size), dest(_dest),
207           addrSizeValid(_req->validPaddr),
208           srcValid(false),
209           req(_req), coherence(NULL), senderState(NULL), cmd(_cmd),
210           result(Unknown)
211    {
212    }
213
214    /** Destructor. */
215    ~Packet()
216    { deleteData(); }
217
218    /** Reinitialize packet address and size from the associated
219     *   Request object, and reset other fields that may have been
220     *   modified by a previous transaction.  Typically called when a
221     *   statically allocated Request/Packet pair is reused for
222     *   multiple transactions. */
223    void reinitFromRequest() {
224        assert(req->validPaddr);
225        addr = req->paddr;
226        size = req->size;
227        addrSizeValid = true;
228        result = Unknown;
229        if (dynamicData) {
230            deleteData();
231            dynamicData = false;
232            arrayData = false;
233        }
234    }
235
236    /** Take a request packet and modify it in place to be suitable
237     *   for returning as a response to that request.  Used for timing
238     *   accesses only.  For atomic and functional accesses, the
239     *   request packet is always implicitly passed back *without*
240     *   modifying the command or destination fields, so this function
241     *   should not be called. */
242    void makeTimingResponse() {
243        assert(needsResponse());
244        int icmd = (int)cmd;
245        icmd &= ~(IsRequest | NeedsResponse);
246        icmd |= IsResponse;
247        cmd = (Command)icmd;
248        dest = src;
249        srcValid = false;
250    }
251
252    /** Set the data pointer to the following value that should not be freed. */
253    template <typename T>
254    void dataStatic(T *p);
255
256    /** Set the data pointer to a value that should have delete [] called on it.
257     */
258    template <typename T>
259    void dataDynamicArray(T *p);
260
261    /** set the data pointer to a value that should have delete called on it. */
262    template <typename T>
263    void dataDynamic(T *p);
264
265    /** return the value of what is pointed to in the packet. */
266    template <typename T>
267    T get();
268
269    /** get a pointer to the data ptr. */
270    template <typename T>
271    T* getPtr();
272
273    /** set the value in the data pointer to v. */
274    template <typename T>
275    void set(T v);
276
277    /** delete the data pointed to in the data pointer. Ok to call to matter how
278     * data was allocted. */
279    void deleteData();
280
281    /** If there isn't data in the packet, allocate some. */
282    void allocate();
283
284    /** Do the packet modify the same addresses. */
285    bool intersect(Packet *p);
286};
287
288bool fixPacket(Packet *func, Packet *timing);
289#endif //__MEM_PACKET_HH
290