public final int pack(int valCount,
                          long[] in, int inOffset,
                          byte[] out, int outOffset) {
        return packUnsafe(valCount,
                in, UnsafeUtil.LONG_ARRAY_OFFSET + (inOffset << 3),
                out, UnsafeUtil.BYTE_ARRAY_OFFSET + outOffset);
    }
unpack bitWidth bytes from input into 8 values in output.
nextPosition: input = (inAddr + bitWidth), output = (outAddr + 8 * 4)
indexr-vlt-segment/src/main/java/io/indexr/vlt/codec/pack/LongPacker.java