decoder.hh revision 9024:5851586f399c 
1/*
2 * Copyright (c) 2012 Google
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: Gabe Black
29 */
30
31#ifndef __ARCH_MIPS_DECODER_HH__
32#define __ARCH_MIPS_DECODER_HH__
33
34#include "arch/generic/decode_cache.hh"
35#include "arch/mips/types.hh"
36#include "base/misc.hh"
37#include "base/types.hh"
38#include "cpu/static_inst.hh"
39
40class ThreadContext;
41
42namespace MipsISA
43{
44
45class Decoder
46{
47  protected:
48    ThreadContext * tc;
49    //The extended machine instruction being generated
50    ExtMachInst emi;
51    bool instDone;
52
53  public:
54    Decoder(ThreadContext * _tc) : tc(_tc), instDone(false)
55    {}
56
57    ThreadContext *getTC()
58    {
59        return tc;
60    }
61
62    void
63    setTC(ThreadContext *_tc)
64    {
65        tc = _tc;
66    }
67
68    void
69    process()
70    {
71    }
72
73    void
74    reset()
75    {
76        instDone = false;
77    }
78
79    //Use this to give data to the decoder. This should be used
80    //when there is control flow.
81    void
82    moreBytes(const PCState &pc, Addr fetchPC, MachInst inst)
83    {
84        emi = inst;
85        instDone = true;
86    }
87
88    bool
89    needMoreBytes()
90    {
91        return true;
92    }
93
94    bool
95    instReady()
96    {
97        return instDone;
98    }
99
100  protected:
101    /// A cache of decoded instruction objects.
102    static GenericISA::BasicDecodeCache defaultCache;
103
104  public:
105    StaticInstPtr decodeInst(ExtMachInst mach_inst);
106
107    /// Decode a machine instruction.
108    /// @param mach_inst The binary instruction to decode.
109    /// @retval A pointer to the corresponding StaticInst object.
110    StaticInstPtr
111    decode(ExtMachInst mach_inst, Addr addr)
112    {
113        return defaultCache.decode(this, mach_inst, addr);
114    }
115
116    StaticInstPtr
117    decode(MipsISA::PCState &nextPC)
118    {
119        if (!instDone)
120            return NULL;
121        instDone = false;
122        return decode(emi, nextPC.instAddr());
123    }
124};
125
126} // namespace MipsISA
127
128#endif // __ARCH_MIPS_DECODER_HH__
129