summaryrefslogtreecommitdiff
path: root/src/arch/mips/decoder.hh
blob: a3a68ad07477be87aef7b7befb07a4cee8c5e8e9 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
/*
 * Copyright (c) 2012 Google
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met: redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer;
 * redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution;
 * neither the name of the copyright holders nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Authors: Gabe Black
 */

#ifndef __ARCH_MIPS_DECODER_HH__
#define __ARCH_MIPS_DECODER_HH__

#include "arch/generic/decode_cache.hh"
#include "arch/mips/types.hh"
#include "base/misc.hh"
#include "base/types.hh"
#include "cpu/static_inst.hh"

namespace MipsISA
{

class Decoder
{
  protected:
    //The extended machine instruction being generated
    ExtMachInst emi;
    bool instDone;

  public:
    Decoder() : instDone(false)
    {}

    void
    process()
    {
    }

    void
    reset()
    {
        instDone = false;
    }

    //Use this to give data to the decoder. This should be used
    //when there is control flow.
    void
    moreBytes(const PCState &pc, Addr fetchPC, MachInst inst)
    {
        emi = inst;
        instDone = true;
    }

    bool
    needMoreBytes()
    {
        return true;
    }

    bool
    instReady()
    {
        return instDone;
    }

    void takeOverFrom(Decoder *old) {}

  protected:
    /// A cache of decoded instruction objects.
    static GenericISA::BasicDecodeCache defaultCache;

  public:
    StaticInstPtr decodeInst(ExtMachInst mach_inst);

    /// Decode a machine instruction.
    /// @param mach_inst The binary instruction to decode.
    /// @retval A pointer to the corresponding StaticInst object.
    StaticInstPtr
    decode(ExtMachInst mach_inst, Addr addr)
    {
        return defaultCache.decode(this, mach_inst, addr);
    }

    StaticInstPtr
    decode(MipsISA::PCState &nextPC)
    {
        if (!instDone)
            return NULL;
        instDone = false;
        return decode(emi, nextPC.instAddr());
    }
};

} // namespace MipsISA

#endif // __ARCH_MIPS_DECODER_HH__