compressednumber.java

derby database source code.good for you.

		out.write((int) ( (value >>> 24) & 0xff));
		out.write((int) ( (value >>> 16) & 0xff));
		out.write((int) ( (value >>>  8) & 0xff));
		out.write((int) ( (value       ) & 0xff));
		return 8;
	}

	/**
		Read a long previously written by writeLong().

		@exception IOException an exception was thrown by a method on in.
	*/
	public static final long readLong(DataInput in) throws IOException {

		int int_value = in.readUnsignedByte();

        if ((int_value & ~0x3f) == 0)
        {
            // test for small case first - assuming this is usual case.
            // this is stored in 2 bytes.

            return((int_value << 8) | in.readUnsignedByte());
		}
		else if ((int_value & 0x80) == 0)
		{
            // value is stored in 4 bytes.  only use low 6 bits from 1st byte.

            return(
                ((int_value & 0x3f)      << 24) |
                (in.readUnsignedByte()   << 16) |
                (in.readUnsignedByte()   <<  8) |
                (in.readUnsignedByte()));
		} 
        else
		{
            // value is stored in 8 bytes.  only use low 7 bits from 1st byte.
            return(
                (((long) (int_value & 0x7f)   ) << 56) |
                (((long) in.readUnsignedByte()) << 48) |
                (((long) in.readUnsignedByte()) << 40) |
                (((long) in.readUnsignedByte()) << 32) |
                (((long) in.readUnsignedByte()) << 24) |
                (((long) in.readUnsignedByte()) << 16) |
                (((long) in.readUnsignedByte()) <<  8) |
                (((long) in.readUnsignedByte())      ));
		}
	}

	/**
		Read a long previously written by writeLong().

		@exception IOException an exception was thrown by a method on in.
	*/
	public static final long readLong(InputStream in) throws IOException {

		int int_value = InputStreamUtil.readUnsignedByte(in);

        if ((int_value & ~0x3f) == 0)
        {
            // test for small case first - assuming this is usual case.
            // this is stored in 2 bytes.

            return((int_value << 8) | InputStreamUtil.readUnsignedByte(in));
		}
		else if ((int_value & 0x80) == 0)
		{
            // value is stored in 4 bytes.  only use low 6 bits from 1st byte.

            return(
                ((int_value      & 0x3f)              << 24) |
                (InputStreamUtil.readUnsignedByte(in) << 16) |
                (InputStreamUtil.readUnsignedByte(in) <<  8) |
                (InputStreamUtil.readUnsignedByte(in)      ));

		} 
        else
		{
            // value is stored in 8 bytes.  only use low 7 bits from 1st byte.
            long value = int_value;

            return(
                (((long) (value & 0x7f)                      ) << 56) |
                (((long) InputStreamUtil.readUnsignedByte(in)) << 48) |
                (((long) InputStreamUtil.readUnsignedByte(in)) << 40) |
                (((long) InputStreamUtil.readUnsignedByte(in)) << 32) |
                (((long) InputStreamUtil.readUnsignedByte(in)) << 24) |
                (((long) InputStreamUtil.readUnsignedByte(in)) << 16) |
                (((long) InputStreamUtil.readUnsignedByte(in)) <<  8) |
                (((long) InputStreamUtil.readUnsignedByte(in))      ));
		}
	}

	public static final long readLong(
    byte[]  data,
    int     offset)
    {
		int int_value = data[offset++];

        if ((int_value & ~0x3f) == 0)
        {
            // test for small case first - assuming this is usual case.
            // this is stored in 2 bytes.

            return((int_value << 8) | (data[offset] & 0xff));
		}
		else if ((int_value & 0x80) == 0)
		{
            // value is stored in 4 bytes.  only use low 6 bits from 1st byte.

            return(
                ((int_value      & 0x3f) << 24) |
                ((data[offset++] & 0xff) << 16) |
                ((data[offset++] & 0xff) <<  8) |
                ((data[offset]   & 0xff)      ));

		} 
        else
		{
            // value is stored in 8 bytes.  only use low 6 bits from 1st byte.
            return(
                (((long) (int_value      & 0x7f)) << 56) |
                (((long) (data[offset++] & 0xff)) << 48) |
                (((long) (data[offset++] & 0xff)) << 40) |
                (((long) (data[offset++] & 0xff)) << 32) |
                (((long) (data[offset++] & 0xff)) << 24) |
                (((long) (data[offset++] & 0xff)) << 16) |
                (((long) (data[offset++] & 0xff)) <<  8) |
                (((long) (data[offset]   & 0xff))      ));

		}
	}

	/**
		Skip a long previously written by writeLong().

		@exception IOException an exception was thrown by a method on in.
	*/
	public static final int skipLong(DataInput in) throws IOException {

		long value = in.readUnsignedByte();

		if ((value & 0x80) == 0x80)
		{
			in.skipBytes(7);
			return 8;
		}
		
		
		if ((value & 0x40) == 0x40)
		{
			in.skipBytes(3);
			return 4;

		}

		in.skipBytes(1);
		return 2;
	}

	/**
		Skip a long previously written by writeLong().

		@exception IOException an exception was thrown by a method on in.
	*/
	public static final int skipLong(InputStream in) throws IOException {

		int value = InputStreamUtil.readUnsignedByte(in);

		int skipBytes;

		if ((value & 0x80) == 0x80) {
			skipBytes = 7;
		}
		else if ((value & 0x40) == 0x40) {
			skipBytes = 3;
		}
		else
			skipBytes = 1;

		if (in.skip(skipBytes) != skipBytes)
			throw new EOFException();

		return skipBytes + 1;
	}

	public static final int sizeLong(long value) {

		if (value <= 0x3fff) {

			return 2;
		}

		if (value <= 0x3fffffff) {
			return 4;
		}

		return 8;
	}

// /* FOR TESTING
// *****************************************************

  	private static byte[] holder = new byte[8];
	private static  ArrayOutputStream aos = new ArrayOutputStream(holder);
	private static  DataOutput out = new DataOutputStream(aos);

	private static  ArrayInputStream ais = new ArrayInputStream(holder);
	private static  DataInput in = new DataInputStream(ais);
	private static  InputStream in_stream = ais;


    private static short checkInt(int i, short oldLength) throws IOException {

		aos.setPosition(0);
		int length = CompressedNumber.writeInt(out, i);
		if (length != oldLength) {
			System.out.println("changing length to " + length + " at value " + i + " 0x" + Integer.toHexString(i));

			oldLength = (short) length;
		}

		int writtenBytes = aos.getPosition();
		if (writtenBytes != length) {
			System.out.println("MISMATCH written bytes  expected " + length + " got " + writtenBytes);
			System.exit(1);
		}

		if (length != CompressedNumber.sizeInt(i)) {
			System.out.println("MISMATCH sizeInt() bytes  expected " + length + " got " + CompressedNumber.sizeInt(i));
			System.exit(1);
		}

		ais.setPosition(0);
		int value = CompressedNumber.readInt(in);
		if (value != i) {
			System.out.println("MISMATCH value readInt(DataInput) expected " + i + " got " + value);
			System.exit(1);
		}

		ais.setPosition(0);
		value = ais.readCompressedInt();
		if (value != i) {
			System.out.println("MISMATCH value readInt(DataInput) expected " + i + " got " + value);
			System.exit(1);
		}

		ais.setPosition(0);
		value = CompressedNumber.readInt(in_stream);
		if (value != i) {
			System.out.println("MISMATCH value in readInt(InputStream) expected " + i + " got " + value);
			System.exit(1);
		}


		value = CompressedNumber.readInt(holder, 0);
		if (value != i) {
			System.out.println(
                "MISMATCH frome readInt(byte[], offset) value expected " + 
                i + " got " + value);
			System.exit(1);
		}

		ais.setPosition(0);
		int skipLength = CompressedNumber.skipInt(in);
		if (skipLength != length) {
			System.out.println("MISMATCH skip length expected " + length + " got " + skipLength);
			System.exit(1);
		}

        int value_plus_int_length = readIntAndReturnIntPlusOverhead(holder, 0);
        if (value_plus_int_length != (length + i + 1)) { 
			System.out.println("MISMATCH readIntAndReturnIntPlusOverhead() return expected " + (length + i) + " got " + value_plus_int_length);
			System.exit(1);
        }

		int skipPosition = ais.getPosition();
		if (skipPosition != length) {
			System.out.println("MISMATCH skip position expected " + length + " got " + skipPosition);
			System.exit(1);
		}

		return oldLength;
	}

    private static short checkLong(long i, short oldLength) throws IOException {

		aos.setPosition(0);
		int length = CompressedNumber.writeLong(out, i);
		if (length != oldLength) {
			System.out.println("changing length to " + length + " at value " + i + " 0x" + Long.toHexString(i));
			oldLength = (short) length;
		}

		int writtenBytes = aos.getPosition();
		if (writtenBytes != length) {
			System.out.println("MISMATCH written bytes  expected " + length + " got " + writtenBytes);
			System.exit(1);
		}

		if (length != CompressedNumber.sizeLong(i)) {
			System.out.println("MISMATCH sizeLong() bytes  expected " + length + " got " + CompressedNumber.sizeLong(i));
			System.exit(1);
		}

		long value = CompressedNumber.readLong(holder, 0);
		if (value != i) {
			for (int j = 0; j < 8; j++) {

				System.out.println(Integer.toHexString((int) holder[j]));
			}

			System.out.println(
                "MISMATCH in readLong(byte[], offset) value expected " + 
                Long.toHexString(i) + " got " + value);
			System.exit(1);
		}

		ais.setPosition(0);
		value = CompressedNumber.readLong(in_stream);
		if (value != i) {
			for (int j = 0; j < 8; j++) {

				System.out.println(Integer.toHexString((int) holder[j]));
			}
			System.out.println("MISMATCH value in readLong(InputStream) expected " + Long.toHexString(i) + " got " + value);
			System.exit(1);
		}

		ais.setPosition(0);
		value = ais.readCompressedLong();
		if (value != i) {
			for (int j = 0; j < 8; j++) {

				System.out.println(Integer.toHexString((int) holder[j]));
			}
			System.out.println("MISMATCH value in readLong(InputStream) expected " + Long.toHexString(i) + " got " + value);
			System.exit(1);
		}


		ais.setPosition(0);
		value = CompressedNumber.readLong(in);
		if (value != i) {
			for (int j = 0; j < 8; j++) {

				System.out.println(Integer.toHexString((int) holder[j]));
			}
			System.out.println("MISMATCH value in readLong(DataInput) expected " + Long.toHexString(i) + " got " + value);
			System.exit(1);
		}

		ais.setPosition(0);
		int skipLength = CompressedNumber.skipLong(in);
		if (skipLength != length) {
			System.out.println("MISMATCH skip length expected " + length + " got " + skipLength);
			System.exit(1);
		}

		int skipPosition = ais.getPosition();
		if (skipPosition != length) {
			System.out.println("MISMATCH skip position expected " + length + " got " + skipPosition);
			System.exit(1);
		}

		return oldLength;
	}

	public static void main(String[] args) throws IOException {

		short oldLength = -1;

		System.out.println("** Testing Int");

		oldLength = checkInt(0, oldLength);
		oldLength = checkInt(1, oldLength);
		oldLength = checkInt(2, oldLength);

		oldLength = checkInt(0x3f - 4, oldLength);
		oldLength = checkInt(0x3f - 3, oldLength);
		oldLength = checkInt(0x3f - 2, oldLength);
		oldLength = checkInt(0x3f - 1, oldLength);
		oldLength = checkInt(0x3f    , oldLength);
		oldLength = checkInt(0x3f + 1, oldLength);
		oldLength = checkInt(0x3f + 2, oldLength);
		oldLength = checkInt(0x3f + 3, oldLength);
		oldLength = checkInt(0x3f + 4, oldLength);

		oldLength = checkInt(0x3f80 - 4, oldLength);
		oldLength = checkInt(0x3f80 - 3, oldLength);
		oldLength = checkInt(0x3f80 - 2, oldLength);
		oldLength = checkInt(0x3f80 - 1, oldLength);
		oldLength = checkInt(0x3f80    , oldLength);
		oldLength = checkInt(0x3f80 + 1, oldLength);
		oldLength = checkInt(0x3f80 + 2, oldLength);
		oldLength = checkInt(0x3f80 + 3, oldLength);
		oldLength = checkInt(0x3f80 + 4, oldLength);

		oldLength = checkInt(0x3fff - 4, oldLength);
		oldLength = checkInt(0x3fff - 3, oldLength);
		oldLength = checkInt(0x3fff - 2, oldLength);
		oldLength = checkInt(0x3fff - 1, oldLength);
		oldLength = checkInt(0x3fff    , oldLength);
		oldLength = checkInt(0x3fff + 1, oldLength);
		oldLength = checkInt(0x3fff + 2, oldLength);
		oldLength = checkInt(0x3fff + 3, oldLength);
		oldLength = checkInt(0x3fff + 4, oldLength);

		oldLength = checkInt(Integer.MAX_VALUE - 4, oldLength);
		oldLength = checkInt(Integer.MAX_VALUE - 3, oldLength);
		oldLength = checkInt(Integer.MAX_VALUE - 2, oldLength);
		oldLength = checkInt(Integer.MAX_VALUE - 1, oldLength);
		oldLength = checkInt(Integer.MAX_VALUE    , oldLength);

        oldLength = -1;
        for (int i = 0; i < 0xf0000; i++)
        {
            oldLength = checkInt(i, oldLength);
        }

        // takes 30 minutes to run.
        //
        // for (int i = 0; i < Integer.MAX_VALUE; i++)
        // {
        // if (i % 0x00800000 == 0)
        // System.out.println("checking: " + i);
        //
        // oldLength = checkInt(i, oldLength);
        // }


		System.out.println("** Testing Long");

        oldLength = -1;
        for (int i = 0; i < 0xf0000; i++)
        {
            oldLength = checkLong(i, oldLength);
        }
	
		oldLength = -1;
		
		oldLength = checkLong(0, oldLength);
		oldLength = checkLong(1, oldLength);
		oldLength = checkLong(2, oldLength);

		oldLength = checkLong(0x3fff - 2, oldLength);
		oldLength = checkLong(0x3fff - 1, oldLength);
		oldLength = checkLong(0x3fff    , oldLength);
		oldLength = checkLong(0x3fff + 1, oldLength);
		oldLength = checkLong(0x3fff + 2, oldLength);

		oldLength = checkLong(0x3fffffff - 4, oldLength);
		oldLength = checkLong(0x3fffffff - 3, oldLength);
		oldLength = checkLong(0x3fffffff - 2, oldLength);
		oldLength = checkLong(0x3fffffff - 1, oldLength);
		oldLength = checkLong(0x3fffffff    , oldLength);
		oldLength = checkLong(0x3fffffff + 1, oldLength);
		oldLength = checkLong(0x3fffffff + 2, oldLength);
		oldLength = checkLong(0x3fffffff + 3, oldLength);
		oldLength = checkLong(0x3fffffff + 4, oldLength);

		oldLength = checkLong(0x70000000 - 2, oldLength);
		oldLength = checkLong(0x70000000 - 1, oldLength);
		oldLength = checkLong(0x70000000    , oldLength);
		oldLength = checkLong(0x70000000 + 1, oldLength);
		oldLength = checkLong(0x70000000 + 2, oldLength);


		oldLength = checkLong(Long.MAX_VALUE - 2, oldLength);
		oldLength = checkLong(Long.MAX_VALUE - 1, oldLength);
		oldLength = checkLong(Long.MAX_VALUE    , oldLength);


	}
// ********************************************************/
}