presto-orc/src/main/java/io/prestosql/orc/stream/DecimalInputStream.java/DecimalInputStream/emitShortDecimal
class DecimalInputStream:    private static void emitShortDecimal(long[] result, int offset, long low, long high)
    {
        boolean negative = (low & 1) == 1;
        long value = (low >>> 1) | (high << 55); // drop the sign bit from low

        if (negative) {
            value += 1;
            value = -value;
        }

        result[offset] = value;
    }