decoder.hh revision 9023:e9201a7bce59
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/types.hh" 35#include "cpu/decode_cache.hh" 36#include "cpu/static_inst_fwd.hh" 37#include "sim/full_system.hh" 38 39namespace AlphaISA 40{ 41 42class Decoder 43{ 44 protected: 45 ThreadContext *tc; 46 47 // The extended machine instruction being generated 48 ExtMachInst ext_inst; 49 bool instDone; 50 51 public: 52 Decoder(ThreadContext * _tc) : tc(_tc), instDone(false) 53 {} 54 55 ThreadContext * 56 getTC() 57 { 58 return tc; 59 } 60 61 void 62 setTC(ThreadContext * _tc) 63 { 64 tc = _tc; 65 } 66 67 void 68 process() 69 { } 70 71 void 72 reset() 73 { 74 instDone = false; 75 } 76 77 // Use this to give data to the predecoder. This should be used 78 // when there is control flow. 79 void 80 moreBytes(const PCState &pc, Addr fetchPC, MachInst inst) 81 { 82 ext_inst = inst; 83 instDone = true; 84 if (FullSystem) 85 ext_inst |= (static_cast<ExtMachInst>(pc.pc() & 0x1) << 32); 86 } 87 88 bool 89 needMoreBytes() 90 { 91 return true; 92 } 93 94 bool 95 instReady() 96 { 97 return instDone; 98 } 99 100 protected: 101 /// A cache of decoded instruction objects. 102 static DecodeCache defaultCache; 103 104 public: 105 StaticInstPtr decodeInst(ExtMachInst mach_inst); 106 107 /// Decode a machine instruction. 108 /// @param mach_inst The binary instruction to decode. 109 /// @retval A pointer to the corresponding StaticInst object. 110 StaticInstPtr 111 decode(ExtMachInst mach_inst, Addr addr) 112 { 113 return defaultCache.decode(this, mach_inst, addr); 114 } 115 116 StaticInstPtr 117 decode(AlphaISA::PCState &nextPC) 118 { 119 if (!instDone) 120 return NULL; 121 instDone = false; 122 return decode(ext_inst, nextPC.instAddr()); 123 } 124}; 125 126} // namespace AlphaISA 127 128#endif // __ARCH_ALPHA_DECODER_HH__ 129