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_SPARC_DECODER_HH__
32#define __ARCH_SPARC_DECODER_HH__
33
34#include "arch/generic/decode_cache.hh"
35#include "arch/sparc/registers.hh"
36#include "arch/types.hh"
37#include "cpu/static_inst.hh"
38
39namespace SparcISA
40{
41
42class ISA;
43class Decoder
44{
45  protected:
46    // The extended machine instruction being generated
47    ExtMachInst emi;
48    bool instDone;
49    RegVal asi;
50
51  public:
52    Decoder(ISA* isa = nullptr) : instDone(false), asi(0)
53    {}
54
55    void process() {}
56
57    void
58    reset()
59    {
60        instDone = false;
61    }
62
63    // Use this to give data to the predecoder. This should be used
64    // when there is control flow.
65    void
66    moreBytes(const PCState &pc, Addr fetchPC, MachInst inst)
67    {
68        emi = inst;
69        // The I bit, bit 13, is used to figure out where the ASI
70        // should come from. Use that in the ExtMachInst. This is
71        // slightly redundant, but it removes the need to put a condition
72        // into all the execute functions
73        if (inst & (1 << 13)) {
74            emi |= (static_cast<ExtMachInst>(
75                        asi << (sizeof(MachInst) * 8)));
76        } else {
77            emi |= (static_cast<ExtMachInst>(bits(inst, 12, 5))
78                    << (sizeof(MachInst) * 8));
79        }
80        instDone = true;
81    }
82
83    bool
84    needMoreBytes()
85    {
86        return true;
87    }
88
89    bool
90    instReady()
91    {
92        return instDone;
93    }
94
95    void
96    setContext(RegVal _asi)
97    {
98        asi = _asi;
99    }
100
101    void takeOverFrom(Decoder *old) {}
102
103  protected:
104    /// A cache of decoded instruction objects.
105    static GenericISA::BasicDecodeCache defaultCache;
106
107  public:
108    StaticInstPtr decodeInst(ExtMachInst mach_inst);
109
110    /// Decode a machine instruction.
111    /// @param mach_inst The binary instruction to decode.
112    /// @retval A pointer to the corresponding StaticInst object.
113    StaticInstPtr
114    decode(ExtMachInst mach_inst, Addr addr)
115    {
116        return defaultCache.decode(this, mach_inst, addr);
117    }
118
119    StaticInstPtr
120    decode(SparcISA::PCState &nextPC)
121    {
122        if (!instDone)
123            return NULL;
124        instDone = false;
125        return decode(emi, nextPC.instAddr());
126    }
127};
128
129} // namespace SparcISA
130
131#endif // __ARCH_SPARC_DECODER_HH__
132