src/arch/sparc/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_SPARC_PREDECODER_HH__
  32 #define __ARCH_SPARC_PREDECODER_HH__
  33
  34 #include "arch/sparc/types.hh"
  35 #include "base/misc.hh"
  36 #include "cpu/thread_context.hh"
  37 #include "sim/host.hh"
  38
  39 class ThreadContext;
  40
  41 namespace SparcISA
  42 {
  43     class Predecoder
  44     {
  45       protected:
  46         ThreadContext * tc;
  47         //The extended machine instruction being generated
  48         ExtMachInst emi;
  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         //Use this to give data to the predecoder. This should be used
  69         //when there is control flow.
  70         void moreBytes(Addr currPC, Addr off, MachInst inst)
  71         {
  72             assert(off == 0);
  73
  74             emi = inst;
  75             //The I bit, bit 13, is used to figure out where the ASI
  76             //should come from. Use that in the ExtMachInst. This is
  77             //slightly redundant, but it removes the need to put a condition
  78             //into all the execute functions
  79             if(inst & (1 << 13))
  80                 emi |= (static_cast<ExtMachInst>(
  81                             tc->readMiscRegNoEffect(MISCREG_ASI))
  82                         << (sizeof(MachInst) * 8));
  83             else
  84                 emi |= (static_cast<ExtMachInst>(bits(inst, 12, 5))
  85                         << (sizeof(MachInst) * 8));
  86         }
  87
  88         //Use this to give data to the predecoder. This should be used
  89         //when instructions are executed in order.
  90         void moreBytes(MachInst machInst)
  91         {
  92             moreBytes(0, 0, machInst);
  93         }
  94
  95         bool needMoreBytes()
  96         {
  97             return true;
  98         }
  99
 100         bool extMachInstReady()
 101         {
 102             return true;
 103         }
 104
 105         //This returns a constant reference to the ExtMachInst to avoid a copy
 106         const ExtMachInst & getExtMachInst()
 107         {
 108             return emi;
 109         }
 110     };
 111 };
 112
 113 #endif // __ARCH_SPARC_PREDECODER_HH__