src/arch/alpha/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_ALPHA_PREDECODER_HH__
  32 #define __ARCH_ALPHA_PREDECODER_HH__
  33
  34 #include "arch/alpha/types.hh"
  35 #include "base/misc.hh"
  36 #include "config/full_system.hh"
  37 #include "sim/host.hh"
  38
  39 class ThreadContext;
  40
  41 namespace AlphaISA
  42 {
  43     class Predecoder
  44     {
  45       protected:
  46         ThreadContext * tc;
  47         //The extended machine instruction being generated
  48         ExtMachInst ext_inst;
  49
  50       public:
  51         Predecoder(ThreadContext * _tc) : tc(_tc)
  52         {}
  53
  54         ThreadContext * getTC()
  55         {
  56             return tc;
  57         }
  58
  59         void setTC(ThreadContext * _tc)
  60         {
  61             tc = _tc;
  62         }
  63
  64         void process()
  65         {
  66         }
  67
  68         void reset()
  69         {}
  70
  71         //Use this to give data to the predecoder. This should be used
  72         //when there is control flow.
  73         void moreBytes(Addr pc, Addr fetchPC, MachInst inst)
  74         {
  75             ext_inst = inst;
  76 #if FULL_SYSTEM
  77             if (pc && 0x1)
  78                 ext_inst|=(static_cast<ExtMachInst>(pc & 0x1) << 32);
  79 #endif
  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 ext_inst;
  96         }
  97     };
  98 };
  99
 100 #endif // __ARCH_ALPHA_PREDECODER_HH__