decoder.hh revision 9377:6f294e7a93d1
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_SPARC_DECODER_HH__ 32#define __ARCH_SPARC_DECODER_HH__ 33 34#include "arch/generic/decode_cache.hh" 35#include "arch/sparc/registers.hh" 36#include "arch/types.hh" 37#include "cpu/static_inst.hh" 38 39namespace SparcISA 40{ 41 42class Decoder 43{ 44 protected: 45 // The extended machine instruction being generated 46 ExtMachInst emi; 47 bool instDone; 48 MiscReg asi; 49 50 public: 51 Decoder() : instDone(false), asi(0) 52 {} 53 54 void process() {} 55 56 void 57 reset() 58 { 59 instDone = false; 60 } 61 62 // Use this to give data to the predecoder. This should be used 63 // when there is control flow. 64 void 65 moreBytes(const PCState &pc, Addr fetchPC, MachInst inst) 66 { 67 emi = inst; 68 // The I bit, bit 13, is used to figure out where the ASI 69 // should come from. Use that in the ExtMachInst. This is 70 // slightly redundant, but it removes the need to put a condition 71 // into all the execute functions 72 if (inst & (1 << 13)) { 73 emi |= (static_cast<ExtMachInst>( 74 asi << (sizeof(MachInst) * 8))); 75 } else { 76 emi |= (static_cast<ExtMachInst>(bits(inst, 12, 5)) 77 << (sizeof(MachInst) * 8)); 78 } 79 instDone = true; 80 } 81 82 bool 83 needMoreBytes() 84 { 85 return true; 86 } 87 88 bool 89 instReady() 90 { 91 return instDone; 92 } 93 94 void 95 setContext(MiscReg _asi) 96 { 97 asi = _asi; 98 } 99 100 protected: 101 /// A cache of decoded instruction objects. 102 static GenericISA::BasicDecodeCache 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(SparcISA::PCState &nextPC) 118 { 119 if (!instDone) 120 return NULL; 121 instDone = false; 122 return decode(emi, nextPC.instAddr()); 123 } 124}; 125 126} // namespace SparcISA 127 128#endif // __ARCH_SPARC_DECODER_HH__ 129