decoder.hh revision 9478
1/* 2 * Copyright (c) 2012 Google 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_DECODER_HH__ 32#define __ARCH_ALPHA_DECODER_HH__ 33 34#include "arch/generic/decode_cache.hh" 35#include "arch/types.hh" 36#include "cpu/static_inst.hh" 37#include "sim/full_system.hh" 38 39namespace AlphaISA 40{ 41 42class Decoder 43{ 44 protected: 45 // The extended machine instruction being generated 46 ExtMachInst ext_inst; 47 bool instDone; 48 49 public: 50 Decoder() : instDone(false) 51 {} 52 53 void 54 process() 55 { } 56 57 void 58 reset() 59 { 60 instDone = false; 61 } 62 63 // Use this to give data to the predecoder. This should be used 64 // when there is control flow. 65 void 66 moreBytes(const PCState &pc, Addr fetchPC, MachInst inst) 67 { 68 ext_inst = inst; 69 instDone = true; 70 if (FullSystem) 71 ext_inst |= (static_cast<ExtMachInst>(pc.pc() & 0x1) << 32); 72 } 73 74 bool 75 needMoreBytes() 76 { 77 return true; 78 } 79 80 bool 81 instReady() 82 { 83 return instDone; 84 } 85 86 void takeOverFrom(Decoder * old) {} 87 88 protected: 89 /// A cache of decoded instruction objects. 90 static GenericISA::BasicDecodeCache defaultCache; 91 92 public: 93 StaticInstPtr decodeInst(ExtMachInst mach_inst); 94 95 /// Decode a machine instruction. 96 /// @param mach_inst The binary instruction to decode. 97 /// @retval A pointer to the corresponding StaticInst object. 98 StaticInstPtr 99 decode(ExtMachInst mach_inst, Addr addr) 100 { 101 return defaultCache.decode(this, mach_inst, addr); 102 } 103 104 StaticInstPtr 105 decode(AlphaISA::PCState &nextPC) 106 { 107 if (!instDone) 108 return NULL; 109 instDone = false; 110 return decode(ext_inst, nextPC.instAddr()); 111 } 112}; 113 114} // namespace AlphaISA 115 116#endif // __ARCH_ALPHA_DECODER_HH__ 117