88 lines
2.0 KiB
C++
88 lines
2.0 KiB
C++
/*
|
|
* Copyright (C) 2015 The Android Open Source Project
|
|
*
|
|
* Licensed under the Apache License, Version 2.0 (the "License");
|
|
* you may not use this file except in compliance with the License.
|
|
* You may obtain a copy of the License at
|
|
*
|
|
* http://www.apache.org/licenses/LICENSE-2.0
|
|
*
|
|
* Unless required by applicable law or agreed to in writing, software
|
|
* distributed under the License is distributed on an "AS IS" BASIS,
|
|
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
* See the License for the specific language governing permissions and
|
|
* limitations under the License.
|
|
*/
|
|
|
|
#ifndef _LINKER_LEB128_H
|
|
#define _LINKER_LEB128_H
|
|
|
|
#include <stdint.h>
|
|
|
|
// Helper classes for decoding LEB128, used in packed relocation data.
|
|
// http://en.wikipedia.org/wiki/LEB128
|
|
|
|
class leb128_decoder {
|
|
public:
|
|
leb128_decoder(const uint8_t* buffer, size_t count)
|
|
: current_(buffer), end_(buffer + count) { }
|
|
|
|
size_t pop_front() {
|
|
size_t value = 0;
|
|
|
|
size_t shift = 0;
|
|
uint8_t byte;
|
|
|
|
do {
|
|
if (current_ >= end_) {
|
|
__libc_fatal("leb128_decoder ran out of bounds");
|
|
}
|
|
byte = *current_++;
|
|
value |= static_cast<size_t>(byte & 127) << shift;
|
|
shift += 7;
|
|
} while (byte & 128);
|
|
|
|
return value;
|
|
}
|
|
|
|
private:
|
|
const uint8_t* current_;
|
|
const uint8_t* const end_;
|
|
};
|
|
|
|
class sleb128_decoder {
|
|
public:
|
|
sleb128_decoder(const uint8_t* buffer, size_t count)
|
|
: current_(buffer), end_(buffer+count) { }
|
|
|
|
size_t pop_front() {
|
|
size_t value = 0;
|
|
static const size_t size = CHAR_BIT * sizeof(value);
|
|
|
|
size_t shift = 0;
|
|
uint8_t byte;
|
|
|
|
do {
|
|
if (current_ >= end_) {
|
|
__libc_fatal("leb128_decoder ran out of bounds");
|
|
}
|
|
byte = *current_++;
|
|
value |= (static_cast<size_t>(byte & 127) << shift);
|
|
shift += 7;
|
|
} while (byte & 128);
|
|
|
|
if (shift < size && (byte & 64)) {
|
|
value |= -(static_cast<size_t>(1) << shift);
|
|
}
|
|
|
|
return value;
|
|
}
|
|
|
|
private:
|
|
const uint8_t* current_;
|
|
const uint8_t* const end_;
|
|
};
|
|
|
|
#endif // __LINKER_LEB128_H
|
|
|