presto-spi/src/main/java/io/prestosql/spi/type/UnscaledDecimal128Arithmetic.java/UnscaledDecimal128Arithmetic/shiftLeftMultiPrecision
class UnscaledDecimal128Arithmetic:    static int[] shiftLeftMultiPrecision(int[] number, int length, int shifts)
    {
        if (shifts == 0) {
            return number;
        }
        // wordShifts = shifts / 32
        int wordShifts = shifts >>> 5;
        // we don't wan't to loose any leading bits
        for (int i = 0; i < wordShifts; i++) {
            checkState(number[length - i - 1] == 0);
        }
        if (wordShifts > 0) {
            arraycopy(number, 0, number, wordShifts, length - wordShifts);
            fill(number, 0, wordShifts, 0);
        }
        // bitShifts = shifts % 32
        int bitShifts = shifts & 0b11111;
        if (bitShifts > 0) {
            // we don't wan't to loose any leading bits
            checkState(number[length - 1] >>> (Integer.SIZE - bitShifts) == 0);
            for (int position = length - 1; position > 0; position--) {
                number[position] = (number[position] << bitShifts) | (number[position - 1] >>> (Integer.SIZE - bitShifts));
            }
            number[0] = number[0] << bitShifts;
        }
        return number;
    }