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 ISA;
42class Decoder
43{
44  protected:
45    // The extended machine instruction being generated
46    ExtMachInst emi;
47    bool instDone;
48
49  public:
50    Decoder(ISA* isa = nullptr) : instDone(false)
51    {
52    }
53
54    void
55    process()
56    {
57    }
58
59    void
60    reset()
61    {
62        instDone = false;
63    }
64
65    // Use this to give data to the predecoder. This should be used
66    // when there is control flow.
67    void
68    moreBytes(const PCState &pc, Addr fetchPC, MachInst inst)
69    {
70        emi = inst;
71        instDone = true;
72    }
73
74    // Use this to give data to the predecoder. This should be used
75    // when instructions are executed in order.
76    void
77    moreBytes(MachInst machInst)
78    {
79        moreBytes(0, 0, machInst);
80    }
81
82    bool
83    needMoreBytes()
84    {
85        return true;
86    }
87
88    bool
89    instReady()
90    {
91        return instDone;
92    }
93
94    void takeOverFrom(Decoder *old) {}
95
96  protected:
97    /// A cache of decoded instruction objects.
98    static GenericISA::BasicDecodeCache defaultCache;
99
100  public:
101    StaticInstPtr decodeInst(ExtMachInst mach_inst);
102
103    /// Decode a machine instruction.
104    /// @param mach_inst The binary instruction to decode.
105    /// @retval A pointer to the corresponding StaticInst object.
106    StaticInstPtr
107    decode(ExtMachInst mach_inst, Addr addr)
108    {
109        return defaultCache.decode(this, mach_inst, addr);
110    }
111
112    StaticInstPtr
113    decode(PowerISA::PCState &nextPC)
114    {
115        if (!instDone)
116            return NULL;
117        instDone = false;
118        return decode(emi, nextPC.instAddr());
119    }
120};
121
122} // namespace PowerISA
123
124#endif // __ARCH_POWER_DECODER_HH__
125