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// int_encoding.cc -- variable length and unaligned integer encoding support.
// Copyright (C) 2009-2020 Free Software Foundation, Inc.
// Written by Doug Kwan <dougkwan@google.com> by refactoring scattered
// contents from other files in gold. Original code written by Ian
// Lance Taylor <iant@google.com> and Caleb Howe <cshowe@google.com>.
// This file is part of gold.
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 3 of the License, or
// (at your option) any later version.
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
// MA 02110-1301, USA.
#include "gold.h"
#include <vector>
#include "int_encoding.h"
namespace gold {
// Read an unsigned LEB128 number. Each byte contains 7 bits of
// information, plus one bit saying whether the number continues or
// not. BYTE contains the first byte of the number, and is guaranteed
// to have the continuation bit set.
uint64_t
read_unsigned_LEB_128_x(const unsigned char* buffer, size_t* len,
unsigned char byte)
{
uint64_t result = static_cast<uint64_t>(byte & 0x7f);
size_t num_read = 1;
unsigned int shift = 7;
do
{
if (num_read > 64 / 7 + 1)
{
gold_warning(_("Unusually large LEB128 decoded, "
"debug information may be corrupted"));
break;
}
byte = *buffer++;
num_read++;
result |= (static_cast<uint64_t>(byte & 0x7f)) << shift;
shift += 7;
}
while (byte & 0x80);
*len = num_read;
return result;
}
// Read a signed LEB128 number. These are like regular LEB128
// numbers, except the last byte may have a sign bit set.
// BYTE contains the first byte of the number, and is guaranteed
// to have the continuation bit set.
int64_t
read_signed_LEB_128_x(const unsigned char* buffer, size_t* len,
unsigned char byte)
{
int64_t result = static_cast<uint64_t>(byte & 0x7f);
int shift = 7;
size_t num_read = 1;
do
{
if (num_read > 64 / 7 + 1)
{
gold_warning(_("Unusually large LEB128 decoded, "
"debug information may be corrupted"));
break;
}
byte = *buffer++;
num_read++;
result |= (static_cast<uint64_t>(byte & 0x7f) << shift);
shift += 7;
}
while (byte & 0x80);
if ((shift < 8 * static_cast<int>(sizeof(result))) && (byte & 0x40))
result |= -((static_cast<int64_t>(1)) << shift);
*len = num_read;
return result;
}
void
write_unsigned_LEB_128(std::vector<unsigned char>* buffer, uint64_t value)
{
do
{
unsigned char current_byte = value & 0x7f;
value >>= 7;
if (value != 0)
{
current_byte |= 0x80;
}
buffer->push_back(current_byte);
}
while (value != 0);
}
size_t
get_length_as_unsigned_LEB_128(uint64_t value)
{
size_t length = 0;
do
{
unsigned char current_byte = value & 0x7f;
value >>= 7;
if (value != 0)
{
current_byte |= 0x80;
}
length++;
}
while (value != 0);
return length;
}
} // End namespace gold.
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