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/*
* Copyright (C) 2014 Apple Inc. All Rights Reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``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 APPLE INC. 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.
*/
#ifndef UnlinkedInstructionStream_h
#define UnlinkedInstructionStream_h
#include "UnlinkedCodeBlock.h"
#include <wtf/RefCountedArray.h>
namespace JSC {
class UnlinkedInstructionStream {
WTF_MAKE_FAST_ALLOCATED;
public:
explicit UnlinkedInstructionStream(const Vector<UnlinkedInstruction>&);
unsigned count() const { return m_instructionCount; }
class Reader {
public:
explicit Reader(const UnlinkedInstructionStream&);
const UnlinkedInstruction* next();
bool atEnd() const { return m_index == m_stream.m_data.size(); }
private:
unsigned char read8();
unsigned read32();
const UnlinkedInstructionStream& m_stream;
UnlinkedInstruction m_unpackedBuffer[16];
unsigned m_index;
};
#ifndef NDEBUG
const RefCountedArray<UnlinkedInstruction>& unpackForDebugging() const;
#endif
private:
friend class Reader;
#ifndef NDEBUG
mutable RefCountedArray<UnlinkedInstruction> m_unpackedInstructionsForDebugging;
#endif
RefCountedArray<unsigned char> m_data;
unsigned m_instructionCount;
};
// Unlinked instructions are packed in a simple stream format.
//
// The first byte is always the opcode.
// It's followed by an opcode-dependent number of argument values.
// The first 3 bits of each value determines the format:
//
// 5-bit positive integer (1 byte total)
// 5-bit negative integer (1 byte total)
// 13-bit positive integer (2 bytes total)
// 13-bit negative integer (2 bytes total)
// 5-bit constant register index, based at 0x40000000 (1 byte total)
// 13-bit constant register index, based at 0x40000000 (2 bytes total)
// 32-bit raw value (5 bytes total)
enum PackedValueType {
Positive5Bit = 0,
Negative5Bit,
Positive13Bit,
Negative13Bit,
ConstantRegister5Bit,
ConstantRegister13Bit,
Full32Bit
};
ALWAYS_INLINE UnlinkedInstructionStream::Reader::Reader(const UnlinkedInstructionStream& stream)
: m_stream(stream)
, m_index(0)
{
}
ALWAYS_INLINE unsigned char UnlinkedInstructionStream::Reader::read8()
{
return m_stream.m_data.data()[m_index++];
}
ALWAYS_INLINE unsigned UnlinkedInstructionStream::Reader::read32()
{
const unsigned char* data = &m_stream.m_data.data()[m_index];
unsigned char type = data[0] >> 5;
switch (type) {
case Positive5Bit:
m_index++;
return data[0];
case Negative5Bit:
m_index++;
return 0xffffffe0 | data[0];
case Positive13Bit:
m_index += 2;
return ((data[0] & 0x1F) << 8) | data[1];
case Negative13Bit:
m_index += 2;
return 0xffffe000 | ((data[0] & 0x1F) << 8) | data[1];
case ConstantRegister5Bit:
m_index++;
return 0x40000000 | (data[0] & 0x1F);
case ConstantRegister13Bit:
m_index += 2;
return 0x40000000 | ((data[0] & 0x1F) << 8) | data[1];
default:
ASSERT(type == Full32Bit);
m_index += 5;
return data[1] | data[2] << 8 | data[3] << 16 | data[4] << 24;
}
}
ALWAYS_INLINE const UnlinkedInstruction* UnlinkedInstructionStream::Reader::next()
{
m_unpackedBuffer[0].u.opcode = static_cast<OpcodeID>(read8());
unsigned opLength = opcodeLength(m_unpackedBuffer[0].u.opcode);
for (unsigned i = 1; i < opLength; ++i)
m_unpackedBuffer[i].u.index = read32();
return m_unpackedBuffer;
}
} // namespace JSC
#endif // UnlinkedInstructionStream_h
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