LibFlute::EncodingSymbol Class Reference

A class for handling FEC encoding symbols. More...

#include <EncodingSymbol.h>

Public Member Functions
	EncodingSymbol (uint32_t id, uint32_t source_block_number, char *encoded_data, size_t data_len, FecScheme fec_scheme)
	Default constructor. More...
virtual	~EncodingSymbol ()
	Default destructor. More...
uint32_t	id () const
	Get the encoding symbol ID. More...
uint32_t	source_block_number () const
	Get the source block number. More...
void	decode_to (char *buffer, size_t max_length) const
	Decode to a buffer. More...
size_t	encode_to (char *buffer, size_t max_length) const
	Encode to a buffer. More...
size_t	len () const
	Get the data length. More...

Static Public Member Functions
static std::vector< EncodingSymbol >	from_payload (char *encoded_data, size_t data_len, const FecOti &fec_oti, ContentEncoding encoding)
	Parse and construct all encoding symbols from a payload data buffer. More...
static size_t	to_payload (const std::vector< EncodingSymbol > &, char *encoded_data, size_t data_len, const FecOti &fec_oti, ContentEncoding encoding)
	Write encoding symbols to a packet payload buffer. More...

Detailed Description

A class for handling FEC encoding symbols.

Definition at line 26 of file EncodingSymbol.h.

Constructor & Destructor Documentation

EncodingSymbol()

LibFlute::EncodingSymbol::EncodingSymbol ( uint32_t  id, uint32_t  source_block_number, char *  encoded_data, size_t  data_len, FecScheme  fec_scheme  )

inline

Default constructor.

Parameters

id	Encoding symbol ID
source_block_number	Source BLock Number of the symbol
encoded_data	Encoded content data
data_len	Length of the encoded data
fec_scheme	FEC scheme to use

Definition at line 47 of file EncodingSymbol.h.

        : _id(id)
        , _source_block_number(source_block_number)
        , _fec_scheme(fec_scheme)
        , _encoded_data(encoded_data)
        , _data_len(data_len)
      {};

~EncodingSymbol()

virtual LibFlute::EncodingSymbol::~EncodingSymbol ( )

inlinevirtual

Default destructor.

Definition at line 58 of file EncodingSymbol.h.

{};

Member Function Documentation

decode_to()

auto LibFlute::EncodingSymbol::decode_to	(	char *	buffer,
		size_t	max_length
	)		const

Decode to a buffer.

Definition at line 87 of file EncodingSymbol.cpp.

                                                                                    {
  if (_fec_scheme == FecScheme::CompactNoCode) {
    if (_data_len <= max_length) {
      memcpy(buffer, _encoded_data, _data_len);
    }
  }
}

encode_to()

auto LibFlute::EncodingSymbol::encode_to	(	char *	buffer,
		size_t	max_length
	)		const

Encode to a buffer.

Definition at line 95 of file EncodingSymbol.cpp.

                                                                                      {
  if (_fec_scheme == FecScheme::CompactNoCode) {
    if (_data_len <= max_length) {
      memcpy(buffer, _encoded_data, _data_len);
      return _data_len;
    }
  }
  return 0;
}

from_payload()

auto LibFlute::EncodingSymbol::from_payload ( char *  encoded_data, size_t  data_len, const FecOti &  fec_oti, ContentEncoding  encoding  )

static

Parse and construct all encoding symbols from a payload data buffer.

Definition at line 25 of file EncodingSymbol.cpp.

{
  auto source_block_number = 0;
  auto encoding_symbol_id = 0;
  std::vector<EncodingSymbol> symbols;
 
  if (encoding != ContentEncoding::NONE && encoding != ContentEncoding::GZIP) {
    throw std::runtime_error("Only unencoded or gzipped content is supported");
  }
 
  if (fec_oti.encoding_id == FecScheme::CompactNoCode) {
    source_block_number = ntohs(*(uint16_t*)encoded_data);
    encoded_data += 2;
    encoding_symbol_id = ntohs(*(uint16_t*)encoded_data);
    encoded_data += 2;
    data_len -= 4;
  } else {
    throw std::runtime_error("Only compact no-code FEC is supported");
  }
 
  int nof_symbols = std::ceil((float)data_len / (float)fec_oti.encoding_symbol_length);
  for (int i = 0; i < nof_symbols; i++) {
    if (fec_oti.encoding_id == FecScheme::CompactNoCode) {
      symbols.emplace_back(encoding_symbol_id, source_block_number, encoded_data, std::min(data_len, (size_t)fec_oti.encoding_symbol_length), fec_oti.encoding_id);
    }
    encoded_data += fec_oti.encoding_symbol_length;
    encoding_symbol_id++;
  }
 
  return symbols;
}

id()

uint32_t LibFlute::EncodingSymbol::id ( ) const

inline

Get the encoding symbol ID.

Definition at line 63 of file EncodingSymbol.h.

{ return _id; };

len()

size_t LibFlute::EncodingSymbol::len ( ) const

inline

Get the data length.

Definition at line 83 of file EncodingSymbol.h.

{ return _data_len; };

source_block_number()

uint32_t LibFlute::EncodingSymbol::source_block_number ( ) const

inline

Get the source block number.

Definition at line 68 of file EncodingSymbol.h.

{ return _source_block_number; };

to_payload()

auto LibFlute::EncodingSymbol::to_payload ( const std::vector< EncodingSymbol > &  symbols, char *  encoded_data, size_t  data_len, const FecOti &  fec_oti, ContentEncoding  encoding  )

static

Write encoding symbols to a packet payload buffer.

Definition at line 57 of file EncodingSymbol.cpp.

{
  size_t len = 0;
  auto ptr = encoded_data;
  auto first_symbol = symbols.begin();
  if (fec_oti.encoding_id == FecScheme::CompactNoCode && data_len >= 4) {
    *((uint16_t*)ptr) = htons(first_symbol->source_block_number());
    ptr += 2;
    *((uint16_t*)ptr) = htons(first_symbol->id());
    ptr += 2;
    len += 4;
    data_len -= 4;
  } else {
    throw std::runtime_error("Only compact no-code FEC is supported");
  }
 
  for (const auto& symbol : symbols) {
    if (symbol.len() <= data_len) {
      auto symbol_len = symbol.encode_to(ptr, data_len);
      data_len -= symbol_len;
      len += symbol_len;
      ptr += symbol_len;
    } else {
      spdlog::warn("Not enough space in payload buffer for encoding symbol");
      break;
    }
  }
  return len;
}

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The documentation for this class was generated from the following files:

• include/EncodingSymbol.h
• src/EncodingSymbol.cpp