var_int.h (1874B)
1 /* 2 * Copyright (c) 2018 The WebRTC project authors. All Rights Reserved. 3 * 4 * Use of this source code is governed by a BSD-style license 5 * that can be found in the LICENSE file in the root of the source 6 * tree. An additional intellectual property rights grant can be found 7 * in the file PATENTS. All contributing project authors may 8 * be found in the AUTHORS file in the root of the source tree. 9 */ 10 11 #ifndef LOGGING_RTC_EVENT_LOG_ENCODER_VAR_INT_H_ 12 #define LOGGING_RTC_EVENT_LOG_ENCODER_VAR_INT_H_ 13 14 #include <stddef.h> 15 #include <stdint.h> 16 17 #include <string> 18 #include <utility> 19 20 #include "absl/strings/string_view.h" 21 #include "rtc_base/bitstream_reader.h" 22 23 namespace webrtc { 24 25 extern const size_t kMaxVarIntLengthBytes; 26 27 // Encode a given uint64_t as a varint. From least to most significant, 28 // each batch of seven bits are put into the lower bits of a byte, and the last 29 // remaining bit in that byte (the highest one) marks whether additional bytes 30 // follow (which happens if and only if there are other bits in `input` which 31 // are non-zero). 32 // Notes: If input == 0, one byte is used. If input is uint64_t::max, exactly 33 // kMaxVarIntLengthBytes are used. 34 std::string EncodeVarInt(uint64_t input); 35 36 // Inverse of EncodeVarInt(). 37 // Returns true and the remaining (unread) slice of the input if decoding 38 // succeeds. Returns false otherwise and `output` is not modified. 39 std::pair<bool, absl::string_view> DecodeVarInt(absl::string_view input, 40 uint64_t* output); 41 42 // Same as other version, but uses a BitstreamReader for input. 43 // If decoding is successful returns the decoded varint. 44 // If not successful, `input` reader is set into the failure state, return value 45 // is unspecified. 46 uint64_t DecodeVarInt(BitstreamReader& input); 47 48 } // namespace webrtc 49 50 #endif // LOGGING_RTC_EVENT_LOG_ENCODER_VAR_INT_H_