bool zfits::ReadBinaryRow ( const size_t &  rowNum, char *  bufferToRead  )

inlineprivate

Definition at line 274 of file zfits.h.

References ___err___, Checksum::add(), buffer, fits::Table::bytes_per_row, clear(), fits::fChkData, fits::fCopy, fHeapFromDataStart, fHeapOff, fNumRowsPerTile, fShrinkFactor, fits::fTable, GetNumRows(), gLog, i, InitCompressionReading(), FITS::kOrderByCol, FITS::kOrderByRow, fits::Table::num_cols, size, FITS::TileHeader::size, fits::Table::sorted_cols, str, TileHeader(), and UncompressBuffer().

Referenced by StageRow().

    {
        if (rowNum >= GetNumRows())
            return false;

        if (!fCatalogInitialized)
            InitCompressionReading();

        // Book keeping, where are we?
        const int64_t requestedTile      = rowNum        / fNumRowsPerTile;
        const int64_t currentTile        = fCurrentRow   / fNumRowsPerTile;

        const int64_t requestedSuperTile = requestedTile / fShrinkFactor;
        //const int64_t currentSuperTile   = currentTile   / fShrinkFactor;

        const int64_t requestedSubTile   = requestedTile % fShrinkFactor;
        //const int64_t currentSubTile     = currentTile   % fShrinkFactor;

        // Is this the first tile we read at all?
        const bool isFirstTile = fCurrentRow<0;

        // Is this just the next tile in the sequence?
        const bool isNextTile = requestedTile==currentTile+1 || isFirstTile;

        fCurrentRow = rowNum;

        // Do we have to read a new tile from disk?
        if (requestedTile!=currentTile || isFirstTile)
        {
            //skip to the beginning of the tile
            const int64_t superTileStart = fCatalog[requestedSuperTile][0].second - sizeof(FITS::TileHeader);

            std::vector<size_t> offsets = fTileOffsets[requestedSuperTile];

            // If this is a sub tile we might have to step forward a bit and
            // seek for the sub tile. If we were just reading the previous one
            // we can skip that.
            if (!isNextTile || isFirstTile)
            {
                // step to the beginnig of the super tile
                seekg(fHeapOff+superTileStart);

                // If there are sub tiles we might have to seek through the super tile
                for (uint32_t k=0; k<requestedSubTile; k++)
                {
                    // Read header
                    FITS::TileHeader header;
                    read((char*)&header, sizeof(FITS::TileHeader));

                    // Skip to the next header
                    seekg(header.size-sizeof(FITS::TileHeader), cur);
                }
            }

            // this is now the beginning of the sub-tile we want to read
            const int64_t subTileStart = tellg() - fHeapOff;
            // calculate the 32 bits offset of the current tile.
            const uint32_t offset = (subTileStart + fHeapFromDataStart)%4;

            // start of destination buffer (padding comes later)
            char *destBuffer = fCompressedBuffer.data()+offset;

            // Store the current tile size once known
            size_t currentTileSize = 0;

            // If this is a request for a sub tile which is not cataloged
            // recalculate the offsets from the buffer, once read
            if (requestedSubTile>0)
            {
                // Read header
                read(destBuffer, sizeof(FITS::TileHeader));

                // Get size of tile
                currentTileSize = reinterpret_cast<FITS::TileHeader*>(destBuffer)->size;

                // now read the remaining bytes of this tile
                read(destBuffer+sizeof(FITS::TileHeader), currentTileSize-sizeof(FITS::TileHeader));

                // Calculate the offsets recursively
                offsets[0] = 0;

                //skip through the columns
                for (size_t i=0; i<fTable.num_cols-1; i++)
                {
                    //zero sized column do not have headers. Skip it
                    if (fTable.sorted_cols[i].num == 0)
                    {
                        offsets[i+1] = offsets[i];
                        continue;
                    }

                    const char *pos = destBuffer + offsets[i] + sizeof(FITS::TileHeader);
                    offsets[i+1] = offsets[i] + reinterpret_cast<const FITS::BlockHeader*>(pos)->size;
                }
            }
            else
            {
                // If we are reading the first tile of a super tile, all information
                // is already available.
                currentTileSize = fTileSize[requestedSuperTile] + sizeof(FITS::TileHeader);
                read(destBuffer, currentTileSize);
            }


            // If we are reading sequentially, calcualte checksum
            if (isNextTile)
            {
                // Padding for checksum calculation
                memset(fCompressedBuffer.data(),   0, offset);
                memset(destBuffer+currentTileSize, 0, fCompressedBuffer.size()-currentTileSize-offset);
                fChkData.add(fCompressedBuffer);
            }

            // Check if we are writing a copy of the file
            if (isNextTile && fCopy.is_open() && fCopy.good())
            {
                fCopy.write(fCompressedBuffer.data()+offset, currentTileSize);
                if (!fCopy)
                    clear(rdstate()|std::ios::badbit);
            }
            else
                if (fCopy.is_open())
                    clear(rdstate()|std::ios::badbit);


            // uncompress  the buffer
            const uint32_t thisRoundNumRows = (GetNumRows()<fCurrentRow + fNumRowsPerTile) ? GetNumRows()%fNumRowsPerTile : fNumRowsPerTile;
            if (!UncompressBuffer(offsets, thisRoundNumRows, offset+sizeof(FITS::TileHeader)))
                return false;

            // pointer to column (source buffer)
            const char *src = fTransposedBuffer.data();

            uint32_t i=0;
            for (auto it=fTable.sorted_cols.cbegin(); it!=fTable.sorted_cols.cend(); it++, i++)
            {
                char *buffer = fBuffer.data() + it->offset; // pointer to column (destination buffer)

                switch (fColumnOrdering[i])
                {
                case FITS::kOrderByRow:
                    // regular, "semi-transposed" copy
                    for (char *dest=buffer; dest<buffer+thisRoundNumRows*fTable.bytes_per_row; dest+=fTable.bytes_per_row) // row-by-row
                    {
                        memcpy(dest, src, it->bytes);
                        src += it->bytes;  // next column
                    }
                    break;

                case FITS::kOrderByCol:
                    // transposed copy
                    for (char *elem=buffer; elem<buffer+it->bytes; elem+=it->size) // element-by-element (arrays)
                    {
                        for (char *dest=elem; dest<elem+thisRoundNumRows*fTable.bytes_per_row; dest+=fTable.bytes_per_row) // row-by-row
                        {
                                memcpy(dest, src, it->size);
                                src += it->size; // next element
                        }
                    }
                    break;

                default:
                    clear(rdstate()|std::ios::badbit);

                    std::ostringstream str;
                    str << "Unkown column ordering scheme found (i=" << i << ", " << fColumnOrdering[i] << ")";
#ifdef __EXCEPTIONS
                    throw std::runtime_error(str.str());
#else
                    gLog << ___err___ << "ERROR - " << str.str() << std::endl;
                    return false;
#endif
                };
            }
        }

        //Data loaded and uncompressed. Copy it to destination
        memcpy(bufferToRead, fBuffer.data()+fTable.bytes_per_row*(fCurrentRow%fNumRowsPerTile), fTable.bytes_per_row);
        return good();
    }

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