Function zlibCompress

src/openrct2/core/Compression.cpp:39–83

    }

    bool zlibCompress(IStream& source, uint64_t sourceLength, IStream& dest, ZlibHeaderType header, int16_t level)
    {
        if (sourceLength > source.GetLength() - source.GetPosition())
            throw IOException("Not Enough Data to Compress");

        StreamReadBuffer sourceBuf(source, sourceLength, kZlibChunkSize);
        StreamWriteBuffer destBuf(dest, zlibCompressBound(sourceLength), kZlibChunkSize);

        z_stream strm{};
        int ret = deflateInit2(&strm, level, Z_DEFLATED, kZlibWindowBits[static_cast<int>(header)], 8, Z_DEFAULT_STRATEGY);
        if (ret != Z_OK)
        {
            LOG_ERROR("Failed to initialise stream");
            return false;
        }

        do
        {
            auto readBlock = sourceBuf.ReadBlock(source, kZlibMaxChunkSize);
            strm.next_in = static_cast<const Bytef*>(readBlock.first);
            strm.avail_in = static_cast<uInt>(readBlock.second);

            do
            {
                Guard::Assert(destBuf, "Compression Overruns Ouput Size");

                auto writeBlock = destBuf.WriteBlockStart(kZlibMaxChunkSize);
                strm.next_out = static_cast<Bytef*>(writeBlock.first);
                strm.avail_out = static_cast<uInt>(writeBlock.second);

                ret = deflate(&strm, sourceBuf ? Z_NO_FLUSH : Z_FINISH);
                if (ret == Z_STREAM_ERROR)
                {
                    LOG_ERROR("Failed to compress data");
                    deflateEnd(&strm);
                    return false;
                }

                destBuf.WriteBlockCommit(dest, writeBlock.second - strm.avail_out);
            } while (strm.avail_in > 0);
        } while (sourceBuf);

        deflateEnd(&strm);
        return true;
    }

    bool zlibDecompress(IStream& source, uint64_t sourceLength, IStream& dest, uint64_t decompressLength, ZlibHeaderType header)
    {