packet.hh revision 2662:f24ae2d09e27 
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
41struct Packet;
42typedef Packet* PacketPtr;
43typedef 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 */
52class 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
289bool fixPacket(Packet *func, Packet *timing);
290#endif //__MEM_PACKET_HH
291