packet.hh revision 2549 
1/*
2 * Copyright (c) 2003 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, a packet is a transaction occuring
32 * between a single level of the memory heirarchy (ie L1->L2).
33 */
34
35#ifndef __MEM_PACKET_HH__
36#define __MEM_PACKET_HH__
37
38#include "mem/request.hh"
39#include "arch/isa_traits.hh"
40#include "sim/root.hh"
41
42struct Packet;
43typedef Packet* PacketPtr;
44typedef uint8_t* PacketDataPtr;
45
46/** List of all commands associated with a packet. */
47enum Command
48{
49    Read,
50    Write
51};
52
53/** The result of a particular pakets request. */
54enum PacketResult
55{
56    Success,
57    BadAddress,
58    Unknown
59};
60
61class SenderState{};
62class Coherence{};
63
64/**
65 * A Packet is the structure to handle requests between two levels
66 * of the memory system.  The Request is a global object that trancends
67 * all of the memory heirarchy, but at each levels interface a packet
68 * is created to transfer data/requests.  For example, a request would
69 * be used to initiate a request to go to memory/IOdevices, as the request
70 * passes through the memory system several packets will be created.  One
71 * will be created to go between the L1 and L2 caches and another to go to
72 * the next level and so forth.
73 *
74 * Packets are assumed to be returned in the case of a single response.  If
75 * the transaction has no response, then the consumer will delete the packet.
76 */
77struct Packet
78{
79    /** The address of the request, could be virtual or physical (depending on
80        cache configurations). */
81    Addr addr;
82
83    /** Flag structure to hold flags for this particular packet */
84    uint64_t flags;
85
86    /** A pointer to the overall request. */
87    RequestPtr req;
88
89    /** A virtual base opaque structure used to hold
90        coherence status messages. */
91    Coherence *coherence;  // virtual base opaque,
92                           // assert(dynamic_cast<Foo>) etc.
93
94    /** A virtual base opaque structure used to hold the senders state. */
95    SenderState *senderState; // virtual base opaque,
96                           // assert(dynamic_cast<Foo>) etc.
97
98    /** A pointer to the data being transfered.  It can be differnt sizes
99        at each level of the heirarchy so it belongs in the packet,
100        not request.
101        This pointer may be NULL! If it isn't null when received by the producer
102        of data it refers to memory that has not been dynamically allocated.
103        Otherwise the producer should simply allocate dynamic memory to use.
104        */
105    PacketDataPtr data;
106
107    /** Indicates the size of the request. */
108    int size;
109
110    /** A index of the source of the transaction. */
111    short src;
112
113    /** A index to the destination of the transaction. */
114    short dest;
115
116    /** The command of the transaction. */
117    Command cmd;
118
119    /** The time this request was responded to. Used to calculate latencies. */
120    Tick time;
121
122    /** The result of the packet transaction. */
123    PacketResult result;
124
125    /** Accessor function that returns the source index of the packet. */
126    short getSrc() const { return src; }
127
128    /** Accessor function that returns the destination index of
129        the packet. */
130    short getDest() const { return dest; }
131
132    Packet()
133        : result(Unknown)
134        {}
135
136    void reset() { result = Unknown; }
137};
138
139#endif //__MEM_PACKET_HH
140