src/arch/mips/predecoder.hh

   1 /*
   2  * Copyright (c) 2006 The Regents of The University of Michigan
   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_MIPS_PREDECODER_HH__
  32 #define __ARCH_MIPS_PREDECODER_HH__
  33
  34 #include "arch/mips/types.hh"
  35 #include "base/misc.hh"
  36 #include "sim/host.hh"
  37
  38 class ThreadContext;
  39
  40 namespace MipsISA
  41 {
  42     class Predecoder
  43     {
  44       protected:
  45         ThreadContext * tc;
  46         //The extended machine instruction being generated
  47         ExtMachInst emi;
  48
  49       public:
  50         Predecoder(ThreadContext * _tc) : tc(_tc)
  51         {}
  52
  53         ThreadContext * getTC()
  54         {
  55             return tc;
  56         }
  57
  58         void setTC(ThreadContext * _tc)
  59         {
  60             tc = _tc;
  61         }
  62
  63         void process()
  64         {
  65         }
  66
  67         //Use this to give data to the predecoder. This should be used
  68         //when there is control flow.
  69         void moreBytes(Addr currPC, Addr off, MachInst inst)
  70         {
  71             assert(off == 0);
  72             emi = inst;
  73         }
  74
  75         //Use this to give data to the predecoder. This should be used
  76         //when instructions are executed in order.
  77         void moreBytes(MachInst machInst)
  78         {
  79             moreBytes(0, 0, machInst);
  80         }
  81
  82         bool needMoreBytes()
  83         {
  84             return true;
  85         }
  86
  87         bool extMachInstReady()
  88         {
  89             return true;
  90         }
  91
  92         //This returns a constant reference to the ExtMachInst to avoid a copy
  93         const ExtMachInst & getExtMachInst()
  94         {
  95             return emi;
  96         }
  97     };
  98 };
  99
 100 #endif // __ARCH_MIPS_PREDECODER_HH__