code: private void srcMemoryToCombinedBuffer(final Memory srcMem, final int serVer,
                                           final boolean srcIsCompact, final int combBufCap) {
      final int preLongs = 2;
      final int extra = (serVer == 1) ? 3 : 2; // space for min and max values, buf alloc (SerVer 1)
      final int preBytes = (preLongs + extra) << 3;
      final int bbCnt = baseBufferCount_;
      final int k = getK();
      final long n = getN();
      final double[] combinedBuffer = new double[combBufCap]; //always non-compact
      //Load min, max
      putMinValue(srcMem.getDouble(MIN_DOUBLE));
      putMaxValue(srcMem.getDouble(MAX_DOUBLE));
  
      if (srcIsCompact) {
        //Load base buffer
        srcMem.getDoubleArray(preBytes, combinedBuffer, 0, bbCnt);
  
        //Load levels from compact srcMem
        long bitPattern = bitPattern_;
        if (bitPattern != 0) {
          long memOffset = preBytes + (bbCnt << 3);
          int combBufOffset = 2 * k;
          while (bitPattern != 0L) {
            if ((bitPattern & 1L) > 0L) {
              srcMem.getDoubleArray(memOffset, combinedBuffer, combBufOffset, k);
              memOffset += (k << 3); //bytes, increment compactly
            }
            combBufOffset += k; //doubles, increment every level
            bitPattern >>>= 1;
          }
  
        }
      } else { //srcMem not compact
        final int levels = Util.computeNumLevelsNeeded(k, n);
        final int totItems = (levels == 0) ? bbCnt : (2 + levels) * k;
        srcMem.getDoubleArray(preBytes, combinedBuffer, 0, totItems);
      }
      putCombinedBuffer(combinedBuffer);
    }
docs: Loads the Combined Buffer, min and max from the given source Memory.
  The resulting Combined Buffer is always in non-compact form and must be pre-allocated.
  @param srcMem the given source Memory
  @param serVer the serialization version of the source
  @param srcIsCompact true if the given source Memory is in compact form
  @param combBufCap total items for the combined buffer (size in doubles)