decoder.hh revision 9023:e9201a7bce59 
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/types.hh"
35#include "cpu/decode_cache.hh"
36#include "cpu/static_inst_fwd.hh"
37
38namespace PowerISA
39{
40
41class Decoder
42{
43  protected:
44    ThreadContext * tc;
45
46    // The extended machine instruction being generated
47    ExtMachInst emi;
48    bool instDone;
49
50  public:
51    Decoder(ThreadContext * _tc) : tc(_tc), instDone(false)
52    {
53    }
54
55    ThreadContext *
56    getTC()
57    {
58        return tc;
59    }
60
61    void
62    setTC(ThreadContext * _tc)
63    {
64        tc = _tc;
65    }
66
67    void
68    process()
69    {
70    }
71
72    void
73    reset()
74    {
75        instDone = false;
76    }
77
78    // Use this to give data to the predecoder. This should be used
79    // when there is control flow.
80    void
81    moreBytes(const PCState &pc, Addr fetchPC, MachInst inst)
82    {
83        emi = inst;
84        instDone = true;
85    }
86
87    // Use this to give data to the predecoder. This should be used
88    // when instructions are executed in order.
89    void
90    moreBytes(MachInst machInst)
91    {
92        moreBytes(0, 0, machInst);
93    }
94
95    bool
96    needMoreBytes()
97    {
98        return true;
99    }
100
101    bool
102    instReady()
103    {
104        return instDone;
105    }
106  protected:
107    /// A cache of decoded instruction objects.
108    static DecodeCache defaultCache;
109
110  public:
111    StaticInstPtr decodeInst(ExtMachInst mach_inst);
112
113    /// Decode a machine instruction.
114    /// @param mach_inst The binary instruction to decode.
115    /// @retval A pointer to the corresponding StaticInst object.
116    StaticInstPtr
117    decode(ExtMachInst mach_inst, Addr addr)
118    {
119        return defaultCache.decode(this, mach_inst, addr);
120    }
121
122    StaticInstPtr
123    decode(PowerISA::PCState &nextPC)
124    {
125        if (!instDone)
126            return NULL;
127        instDone = false;
128        return decode(emi, nextPC.instAddr());
129    }
130};
131
132} // namespace PowerISA
133
134#endif // __ARCH_POWER_DECODER_HH__
135