public void putValue(int packId, long value, long packMin, long packMax) {
        assert packId >= 0 && packId < packCount;
        int packOffset = packId << PACK_HIST_SIZE_BYTE_SHIFT;
        doPutValue(bufferAddr + packOffset, value, packMin, packMax, isFloat);
    }
Each pack (with 65536 values), we use 128 bytes, i.e. 1024 bits to index.
indexr-segment/src/main/java/io/indexr/segment/index/RSIndex_Histogram.java