blob: dbe1f1103f0b0ee1611f990f563fc9ecdc3c9a36 [file] [log] [blame]
* Copyright (c) 2018 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 <stddef.h>
#include <stdint.h>
#include <string>
#include <utility>
#include "absl/strings/string_view.h"
#include "rtc_base/bit_buffer.h"
namespace webrtc {
extern const size_t kMaxVarIntLengthBytes;
// Encode a given uint64_t as a varint. From least to most significant,
// each batch of seven bits are put into the lower bits of a byte, and the last
// remaining bit in that byte (the highest one) marks whether additional bytes
// follow (which happens if and only if there are other bits in `input` which
// are non-zero).
// Notes: If input == 0, one byte is used. If input is uint64_t::max, exactly
// kMaxVarIntLengthBytes are used.
std::string EncodeVarInt(uint64_t input);
// Inverse of EncodeVarInt().
// Returns true and the remaining (unread) slice of the input if decoding
// succeeds. Returns false otherwise and `output` is not modified.
std::pair<bool, absl::string_view> DecodeVarInt(absl::string_view input,
uint64_t* output);
// Same as other version, but uses a rtc::BitBuffer for input.
// If decoding is successful, a non-zero number is returned, indicating the
// number of bytes read from `input`, and the decoded varint is written
// into `output`.
// If not successful, 0 is returned, and `output` is not modified.
// Some bits may be consumed even if a varint fails to be read.
size_t DecodeVarInt(rtc::BitBuffer* input, uint64_t* output);
} // namespace webrtc