135 lines
3.5 KiB
C++
135 lines
3.5 KiB
C++
// int_encoding.cc -- variable length and unaligned integer encoding support.
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// Copyright (C) 2009-2017 Free Software Foundation, Inc.
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// Written by Doug Kwan <dougkwan@google.com> by refactoring scattered
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// contents from other files in gold. Original code written by Ian
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// Lance Taylor <iant@google.com> and Caleb Howe <cshowe@google.com>.
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// This file is part of gold.
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// This program is free software; you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 3 of the License, or
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// (at your option) any later version.
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License
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// along with this program; if not, write to the Free Software
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// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
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// MA 02110-1301, USA.
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#include "gold.h"
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#include <vector>
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#include "int_encoding.h"
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namespace gold {
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// Read an unsigned LEB128 number. Each byte contains 7 bits of
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// information, plus one bit saying whether the number continues or
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// not. BYTE contains the first byte of the number, and is guaranteed
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// to have the continuation bit set.
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uint64_t
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read_unsigned_LEB_128_x(const unsigned char* buffer, size_t* len,
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unsigned char byte)
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{
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uint64_t result = static_cast<uint64_t>(byte & 0x7f);
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size_t num_read = 1;
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unsigned int shift = 7;
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do
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{
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if (num_read > 64 / 7 + 1)
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{
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gold_warning(_("Unusually large LEB128 decoded, "
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"debug information may be corrupted"));
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break;
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}
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byte = *buffer++;
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num_read++;
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result |= (static_cast<uint64_t>(byte & 0x7f)) << shift;
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shift += 7;
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}
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while (byte & 0x80);
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*len = num_read;
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return result;
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}
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// Read a signed LEB128 number. These are like regular LEB128
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// numbers, except the last byte may have a sign bit set.
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// BYTE contains the first byte of the number, and is guaranteed
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// to have the continuation bit set.
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int64_t
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read_signed_LEB_128_x(const unsigned char* buffer, size_t* len,
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unsigned char byte)
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{
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int64_t result = static_cast<uint64_t>(byte & 0x7f);
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int shift = 7;
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size_t num_read = 1;
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do
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{
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if (num_read > 64 / 7 + 1)
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{
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gold_warning(_("Unusually large LEB128 decoded, "
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"debug information may be corrupted"));
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break;
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}
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byte = *buffer++;
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num_read++;
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result |= (static_cast<uint64_t>(byte & 0x7f) << shift);
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shift += 7;
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}
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while (byte & 0x80);
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if ((shift < 8 * static_cast<int>(sizeof(result))) && (byte & 0x40))
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result |= -((static_cast<int64_t>(1)) << shift);
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*len = num_read;
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return result;
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}
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void
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write_unsigned_LEB_128(std::vector<unsigned char>* buffer, uint64_t value)
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{
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do
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{
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unsigned char current_byte = value & 0x7f;
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value >>= 7;
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if (value != 0)
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{
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current_byte |= 0x80;
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}
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buffer->push_back(current_byte);
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}
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while (value != 0);
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}
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size_t
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get_length_as_unsigned_LEB_128(uint64_t value)
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{
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size_t length = 0;
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do
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{
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unsigned char current_byte = value & 0x7f;
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value >>= 7;
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if (value != 0)
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{
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current_byte |= 0x80;
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}
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length++;
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}
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while (value != 0);
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return length;
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}
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} // End namespace gold.
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