decoder.hh revision 9377:6f294e7a93d1 
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_POWER_DECODER_HH__
32#define __ARCH_POWER_DECODER_HH__
33
34#include "arch/generic/decode_cache.hh"
35#include "arch/types.hh"
36#include "cpu/static_inst.hh"
37
38namespace PowerISA
39{
40
41class Decoder
42{
43  protected:
44    // The extended machine instruction being generated
45    ExtMachInst emi;
46    bool instDone;
47
48  public:
49    Decoder() : instDone(false)
50    {
51    }
52
53    void
54    process()
55    {
56    }
57
58    void
59    reset()
60    {
61        instDone = false;
62    }
63
64    // Use this to give data to the predecoder. This should be used
65    // when there is control flow.
66    void
67    moreBytes(const PCState &pc, Addr fetchPC, MachInst inst)
68    {
69        emi = inst;
70        instDone = true;
71    }
72
73    // Use this to give data to the predecoder. This should be used
74    // when instructions are executed in order.
75    void
76    moreBytes(MachInst machInst)
77    {
78        moreBytes(0, 0, machInst);
79    }
80
81    bool
82    needMoreBytes()
83    {
84        return true;
85    }
86
87    bool
88    instReady()
89    {
90        return instDone;
91    }
92  protected:
93    /// A cache of decoded instruction objects.
94    static GenericISA::BasicDecodeCache defaultCache;
95
96  public:
97    StaticInstPtr decodeInst(ExtMachInst mach_inst);
98
99    /// Decode a machine instruction.
100    /// @param mach_inst The binary instruction to decode.
101    /// @retval A pointer to the corresponding StaticInst object.
102    StaticInstPtr
103    decode(ExtMachInst mach_inst, Addr addr)
104    {
105        return defaultCache.decode(this, mach_inst, addr);
106    }
107
108    StaticInstPtr
109    decode(PowerISA::PCState &nextPC)
110    {
111        if (!instDone)
112            return NULL;
113        instDone = false;
114        return decode(emi, nextPC.instAddr());
115    }
116};
117
118} // namespace PowerISA
119
120#endif // __ARCH_POWER_DECODER_HH__
121