Method ExtendColumns

srtcore/fec.cpp:2492–2583

}

size_t FECFilterBuiltin::ExtendColumns(size_t colgx)
{
    // This isn't safe to allow the group container to get expanded to any
    // size, however with some very tolerant settings, such as 10 seconds of
    // latency and very large receiver buffer, this might be tolerable.
    //
    // Therefore put only two conditions here:
    //
    // 1. The group containers must keep at most place for so many
    // packets as it is intended for the receiver buffer. Keeping
    // group cells for more packets doesn't make sense anyway.
    //
    // 2. Existing group containers should contain at least size
    // for two series. If they don't contain that much, there's no
    // need to do any emergency shrinking. Unknown whether this is
    // physically possible, although it may also happen in case when
    // you have very large FEC matrix size not coordinated with the
    // receiver buffer size.

    // colgx is the number of column + NSERIES * numberCols().
    // We can state that for every column we should have a number
    // of packets as many as the number of rows, so simply multiply this.
    const size_t size_in_packets = colgx * numberRows();
    const size_t n_series = colgx / numberCols();

    if (CheckEmergencyShrink(n_series, size_in_packets))
    {
        HLOGC(pflog.Debug, log << "FEC: DONE Emergency resize, colgx=" << colgx << " series=" << n_series
                << "npackets=" << size_in_packets << " exceeds buf=" << rcvBufferSize());
    }
    else
    {
        HLOGC(pflog.Debug, log << "FEC: Will extend up to colgx=" << colgx << " series=" << n_series
                << " for npackets=" << size_in_packets);
    }


#if ENABLE_HEAVY_LOGGING
    LOGC(pflog.Debug, log << "FEC: COL STATS BEFORE: n=" << rcv.colq.size());

    for (size_t i = 0; i < rcv.colq.size(); ++i)
        LOGC(pflog.Debug, log << "... [" << i << "] " << rcv.colq[i].DisplayStats());
#endif

    // First, obtain the "series" of columns, possibly fixed.
    const int series = int(colgx / numberCols());

    // Now, the base of the series is the base increased by one matrix size.

    const int32_t base = rcv.colq[0].base;

    // This is the base for series 0, but this procedure must be prepared
    // for that the series will not necessarily be 1, may be greater.
    // Extension requires to be done in order to achieve this very index
    // existing in the column, so you need to add whole series in loop
    // until the series covering this shift is created.

    // Check, up to which series the columns are initialized.