decoder.cc 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#include "arch/arm/decoder.hh" 32#include "arch/arm/isa_traits.hh" 33#include "arch/arm/utility.hh" 34#include "base/trace.hh" 35#include "cpu/thread_context.hh" 36#include "debug/Decoder.hh" 37 38namespace ArmISA 39{ 40 41DecodeCache Decoder::defaultCache; 42 43void 44Decoder::process() 45{ 46 // emi is typically ready, with some caveats below... 47 instDone = true; 48 49 if (!emi.thumb) { 50 emi.instBits = data; 51 emi.sevenAndFour = bits(data, 7) && bits(data, 4); 52 emi.isMisc = (bits(data, 24, 23) == 0x2 && 53 bits(data, 20) == 0); 54 consumeBytes(4); 55 DPRINTF(Decoder, "Arm inst: %#x.\n", (uint64_t)emi); 56 } else { 57 uint16_t word = (data >> (offset * 8)); 58 if (bigThumb) { 59 // A 32 bit thumb inst is half collected. 60 emi.instBits = emi.instBits | word; 61 bigThumb = false; 62 consumeBytes(2); 63 DPRINTF(Decoder, "Second half of 32 bit Thumb: %#x.\n", 64 emi.instBits); 65 } else { 66 uint16_t highBits = word & 0xF800; 67 if (highBits == 0xE800 || highBits == 0xF000 || 68 highBits == 0xF800) { 69 // The start of a 32 bit thumb inst. 70 emi.bigThumb = 1; 71 if (offset == 0) { 72 // We've got the whole thing. 73 emi.instBits = (data >> 16) | (data << 16); 74 DPRINTF(Decoder, "All of 32 bit Thumb: %#x.\n", 75 emi.instBits); 76 consumeBytes(4); 77 } else { 78 // We only have the first half word. 79 DPRINTF(Decoder, 80 "First half of 32 bit Thumb.\n"); 81 emi.instBits = (uint32_t)word << 16; 82 bigThumb = true; 83 consumeBytes(2); 84 // emi not ready yet. 85 instDone = false; 86 } 87 } else { 88 // A 16 bit thumb inst. 89 consumeBytes(2); 90 emi.instBits = word; 91 // Set the condition code field artificially. 92 emi.condCode = COND_UC; 93 DPRINTF(Decoder, "16 bit Thumb: %#x.\n", 94 emi.instBits); 95 if (bits(word, 15, 8) == 0xbf && 96 bits(word, 3, 0) != 0x0) { 97 foundIt = true; 98 itBits = bits(word, 7, 0); 99 DPRINTF(Decoder, 100 "IT detected, cond = %#x, mask = %#x\n", 101 itBits.cond, itBits.mask); 102 } 103 } 104 } 105 } 106} 107 108//Use this to give data to the decoder. This should be used 109//when there is control flow. 110void 111Decoder::moreBytes(const PCState &pc, Addr fetchPC, MachInst inst) 112{ 113 data = inst; 114 offset = (fetchPC >= pc.instAddr()) ? 0 : pc.instAddr() - fetchPC; 115 emi.thumb = pc.thumb(); 116 FPSCR fpscr = tc->readMiscReg(MISCREG_FPSCR); 117 emi.fpscrLen = fpscr.len; 118 emi.fpscrStride = fpscr.stride; 119 120 outOfBytes = false; 121 process(); 122} 123 124} 125