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Diffstat (limited to 'lib/edi/PFT.hpp')
-rw-r--r-- | lib/edi/PFT.hpp | 166 |
1 files changed, 166 insertions, 0 deletions
diff --git a/lib/edi/PFT.hpp b/lib/edi/PFT.hpp new file mode 100644 index 0000000..779509b --- /dev/null +++ b/lib/edi/PFT.hpp @@ -0,0 +1,166 @@ +/* ------------------------------------------------------------------ + * Copyright (C) 2017 AVT GmbH - Fabien Vercasson + * Copyright (C) 2017 Matthias P. Braendli + * matthias.braendli@mpb.li + * + * http://opendigitalradio.org + * + * 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. + * ------------------------------------------------------------------- + */ + +#pragma once +#include <stdio.h> +#include <vector> +#include <map> +#include <stdint.h> + +namespace EdiDecoder { +namespace PFT { + +using pseq_t = uint16_t; +using findex_t = uint32_t; // findex is a 24-bit value + +class Fragment +{ + public: + // Load the data for one fragment from buf into + // the Fragment. + // \returns the number of bytes of useful data found in buf + // A non-zero return value doesn't imply a valid fragment + // the isValid() method must be used to verify this. + size_t loadData(const std::vector<uint8_t> &buf); + + bool isValid() const { return _valid; } + pseq_t Pseq() const { return _Pseq; } + findex_t Findex() const { return _Findex; } + findex_t Fcount() const { return _Fcount; } + bool FEC() const { return _FEC; } + uint16_t Plen() const { return _Plen; } + uint8_t RSk() const { return _RSk; } + uint8_t RSz() const { return _RSz; } + const std::vector<uint8_t>& payload() const + { return _payload; } + + bool checkConsistency(const Fragment& other) const; + + private: + std::vector<uint8_t> _payload; + + pseq_t _Pseq = 0; + findex_t _Findex = 0; + findex_t _Fcount = 0; + bool _FEC = false; + bool _Addr = false; + uint16_t _Plen = 0; + uint8_t _RSk = 0; + uint8_t _RSz = 0; + uint16_t _Source = 0; + uint16_t _Dest = 0; + bool _valid = false; +}; + +/* The AFBuilder collects Fragments and builds an Application Frame + * out of them. It does error correction if necessary + */ +class AFBuilder +{ + public: + enum class decode_attempt_result_t { + yes, // The AF packet can be build because all fragments are present + maybe, // RS decoding may correctly decode the AF packet + no, // Not enough fragments present to permit RS + }; + + static std::string dar_to_string(decode_attempt_result_t dar) { + switch (dar) { + case decode_attempt_result_t::yes: return "y"; + case decode_attempt_result_t::no: return "n"; + case decode_attempt_result_t::maybe: return "m"; + } + return "?"; + } + + AFBuilder(pseq_t Pseq, findex_t Fcount, size_t lifetime); + + void pushPFTFrag(const Fragment &frag); + + /* Assess if it may be possible to decode this AF packet */ + decode_attempt_result_t canAttemptToDecode() const; + + /* Try to build the AF with received fragments. + * Apply error correction if necessary (missing packets/CRC errors) + * \return an empty vector if building the AF is not possible + */ + std::vector<uint8_t> extractAF(void) const; + + std::pair<findex_t, findex_t> + numberOfFragments(void) const { + return {_fragments.size(), _Fcount}; + } + + std::string visualise(void) const; + + /* The user of this instance can keep track of the lifetime of this + * builder + */ + size_t lifeTime; + + private: + + // A map from fragment index to fragment + std::map<findex_t, Fragment> _fragments; + + // cached version of decoded AF packet + mutable std::vector<uint8_t> _af_packet; + + pseq_t _Pseq; + findex_t _Fcount; +}; + +class PFT +{ + public: + void pushPFTFrag(const Fragment &fragment); + + /* Try to build the AF packet for the next pseq. This might + * skip one or more pseq according to the maximum delay setting. + * + * \return an empty vector if building the AF is not possible + */ + std::vector<uint8_t> getNextAFPacket(void); + + /* Set the maximum delay in number of AF Packets before we + * abandon decoding a given pseq. + */ + void setMaxDelay(size_t num_af_packets); + + /* Enable verbose fprintf */ + void setVerbose(bool enable); + + private: + void incrementNextPseq(void); + + pseq_t m_next_pseq; + size_t m_max_delay = 10; // in AF packets + + // Keep one AFBuilder for each Pseq + std::map<pseq_t, AFBuilder> m_afbuilders; + + bool m_verbose = 0; +}; + +} + +} |