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/registers.hh"
  35 #include "arch/sparc/types.hh"
  36 #include "base/bitfield.hh"
  37 #include "base/misc.hh"
  38 #include "base/types.hh"
  39 #include "cpu/thread_context.hh"
  40
  41 class ThreadContext;
  42
  43 namespace SparcISA
  44 {
  45     class Predecoder
  46     {
  47       protected:
  48         ThreadContext * tc;
  49         //The extended machine instruction being generated
  50         ExtMachInst emi;
  51
  52       public:
  53         Predecoder(ThreadContext * _tc) : tc(_tc)
  54         {}
  55
  56         ThreadContext * getTC()
  57         {
  58             return tc;
  59         }
  60
  61         void setTC(ThreadContext * _tc)
  62         {
  63             tc = _tc;
  64         }
  65
  66         void process()
  67         {
  68         }
  69
  70         void reset()
  71         {}
  72
  73         //Use this to give data to the predecoder. This should be used
  74         //when there is control flow.
  75         void moreBytes(Addr pc, Addr fetchPC, MachInst inst)
  76         {
  77             emi = inst;
  78             //The I bit, bit 13, is used to figure out where the ASI
  79             //should come from. Use that in the ExtMachInst. This is
  80             //slightly redundant, but it removes the need to put a condition
  81             //into all the execute functions
  82             if(inst & (1 << 13))
  83                 emi |= (static_cast<ExtMachInst>(
  84                             tc->readMiscRegNoEffect(MISCREG_ASI))
  85                         << (sizeof(MachInst) * 8));
  86             else
  87                 emi |= (static_cast<ExtMachInst>(bits(inst, 12, 5))
  88                         << (sizeof(MachInst) * 8));
  89         }
  90
  91         bool needMoreBytes()
  92         {
  93             return true;
  94         }
  95
  96         bool extMachInstReady()
  97         {
  98             return true;
  99         }
 100
 101         //This returns a constant reference to the ExtMachInst to avoid a copy
 102         const ExtMachInst & getExtMachInst()
 103         {
 104             return emi;
 105         }
 106     };
 107 };
 108
 109 #endif // __ARCH_SPARC_PREDECODER_HH__