src/arch/mips/predecoder.hh

   1
   2 /*
   3  * Copyright (c) 2006 The Regents of The University of Michigan
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions are
   8  * met: redistributions of source code must retain the above copyright
   9  * notice, this list of conditions and the following disclaimer;
  10  * redistributions in binary form must reproduce the above copyright
  11  * notice, this list of conditions and the following disclaimer in the
  12  * documentation and/or other materials provided with the distribution;
  13  * neither the name of the copyright holders nor the names of its
  14  * contributors may be used to endorse or promote products derived from
  15  * this software without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  18  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  19  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  20  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  21  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  22  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  23  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  24  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  25  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  26  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  27  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  28  *
  29  * Authors: Gabe Black
  30  */
  31
  32 #ifndef __ARCH_MIPS_PREDECODER_HH__
  33 #define __ARCH_MIPS_PREDECODER_HH__
  34
  35 #include "arch/mips/types.hh"
  36 #include "base/misc.hh"
  37 #include "base/types.hh"
  38
  39 class ThreadContext;
  40
  41 namespace MipsISA
  42 {
  43
  44 class Predecoder
  45 {
  46   protected:
  47     ThreadContext * tc;
  48     //The extended machine instruction being generated
  49     ExtMachInst emi;
  50     bool emiIsReady;
  51
  52   public:
  53     Predecoder(ThreadContext * _tc) : tc(_tc), emiIsReady(false)
  54     {}
  55
  56     ThreadContext *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         emiIsReady = false;
  76     }
  77
  78     void
  79     reset(const ExtMachInst &old_emi)
  80     {
  81         reset();
  82     }
  83
  84     //Use this to give data to the predecoder. This should be used
  85     //when there is control flow.
  86     void
  87     moreBytes(const PCState &pc, Addr fetchPC, MachInst inst)
  88     {
  89         emi = inst;
  90         emiIsReady = true;
  91     }
  92
  93     bool
  94     needMoreBytes()
  95     {
  96         return true;
  97     }
  98
  99     bool
 100     extMachInstReady()
 101     {
 102         return emiIsReady;
 103     }
 104
 105     //This returns a constant reference to the ExtMachInst to avoid a copy
 106     const ExtMachInst &
 107     getExtMachInst(PCState &pc)
 108     {
 109         emiIsReady = false;
 110         return emi;
 111     }
 112 };
 113
 114 };
 115
 116 #endif // __ARCH_MIPS_PREDECODER_HH__