presto-orc/src/main/java/io/prestosql/orc/stream/LongInputStreamV2.java/LongInputStreamV2/readDirectValues
class LongInputStreamV2:    private void readDirectValues(int firstByte)
            throws IOException
    {
        // extract the number of fixed bits
        int fixedBits = LongDecode.decodeBitWidth((firstByte >>> 1) & 0b1_1111);

        // extract the run length
        int length = (firstByte & 0b1) << 8;
        length |= input.read();
        // runs are one off
        length += 1;

        // write the unpacked values and zigzag decode to result buffer
        packer.unpack(literals, numLiterals, length, fixedBits, input);
        if (signed) {
            for (int i = 0; i < length; i++) {
                literals[numLiterals] = LongDecode.zigzagDecode(literals[numLiterals]);
                numLiterals++;
            }
        }
        else {
            numLiterals += length;
        }
    }