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/*
* Copyright (c) 2023 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#include "modules/rtp_rtcp/source/leb128.h"
#include <cstdint>
namespace webrtc {
int Leb128Size(uint64_t value) {
int size = 0;
while (value >= 0x80) {
++size;
value >>= 7;
}
return size + 1;
}
uint64_t ReadLeb128(const uint8_t*& read_at, const uint8_t* end) {
uint64_t value = 0;
int fill_bits = 0;
while (read_at != end && fill_bits < 64 - 7) {
uint8_t leb128_byte = *read_at;
value |= uint64_t{leb128_byte & 0x7Fu} << fill_bits;
++read_at;
fill_bits += 7;
if ((leb128_byte & 0x80) == 0) {
return value;
}
}
// Read 9 bytes and didn't find the terminator byte. Check if 10th byte
// is that terminator, however to fit result into uint64_t it may carry only
// single bit.
if (read_at != end && *read_at <= 1) {
value |= uint64_t{*read_at} << fill_bits;
++read_at;
return value;
}
// Failed to find terminator leb128 byte.
read_at = nullptr;
return 0;
}
int WriteLeb128(uint64_t value, uint8_t* buffer) {
int size = 0;
while (value >= 0x80) {
buffer[size] = 0x80 | (value & 0x7F);
++size;
value >>= 7;
}
buffer[size] = value;
++size;
return size;
}
} // namespace webrtc
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