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/*
* Copyright (c) 2012 Google
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met: redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer;
* redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution;
* neither the name of the copyright holders nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* Authors: Gabe Black
*/
#include "arch/arm/decoder.hh"
#include "arch/arm/isa_traits.hh"
#include "arch/arm/utility.hh"
#include "base/trace.hh"
#include "debug/Decoder.hh"
namespace ArmISA
{
GenericISA::BasicDecodeCache Decoder::defaultCache;
void
Decoder::process()
{
// emi is typically ready, with some caveats below...
instDone = true;
if (!emi.thumb) {
emi.instBits = data;
emi.sevenAndFour = bits(data, 7) && bits(data, 4);
emi.isMisc = (bits(data, 24, 23) == 0x2 &&
bits(data, 20) == 0);
consumeBytes(4);
DPRINTF(Decoder, "Arm inst: %#x.\n", (uint64_t)emi);
} else {
uint16_t word = (data >> (offset * 8));
if (bigThumb) {
// A 32 bit thumb inst is half collected.
emi.instBits = emi.instBits | word;
bigThumb = false;
consumeBytes(2);
DPRINTF(Decoder, "Second half of 32 bit Thumb: %#x.\n",
emi.instBits);
} else {
uint16_t highBits = word & 0xF800;
if (highBits == 0xE800 || highBits == 0xF000 ||
highBits == 0xF800) {
// The start of a 32 bit thumb inst.
emi.bigThumb = 1;
if (offset == 0) {
// We've got the whole thing.
emi.instBits = (data >> 16) | (data << 16);
DPRINTF(Decoder, "All of 32 bit Thumb: %#x.\n",
emi.instBits);
consumeBytes(4);
} else {
// We only have the first half word.
DPRINTF(Decoder,
"First half of 32 bit Thumb.\n");
emi.instBits = (uint32_t)word << 16;
bigThumb = true;
consumeBytes(2);
// emi not ready yet.
instDone = false;
}
} else {
// A 16 bit thumb inst.
consumeBytes(2);
emi.instBits = word;
// Set the condition code field artificially.
emi.condCode = COND_UC;
DPRINTF(Decoder, "16 bit Thumb: %#x.\n",
emi.instBits);
if (bits(word, 15, 8) == 0xbf &&
bits(word, 3, 0) != 0x0) {
foundIt = true;
itBits = bits(word, 7, 0);
DPRINTF(Decoder,
"IT detected, cond = %#x, mask = %#x\n",
itBits.cond, itBits.mask);
}
}
}
}
}
//Use this to give data to the decoder. This should be used
//when there is control flow.
void
Decoder::moreBytes(const PCState &pc, Addr fetchPC, MachInst inst)
{
data = inst;
offset = (fetchPC >= pc.instAddr()) ? 0 : pc.instAddr() - fetchPC;
emi.thumb = pc.thumb();
emi.fpscrLen = fpscrLen;
emi.fpscrStride = fpscrStride;
outOfBytes = false;
process();
}
}
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