org.apache.derby.iapi.services.io

Class CompressedNumber

java.lang.Object

org.apache.derby.iapi.services.io.CompressedNumber

public abstract class CompressedNumber
extends java.lang.Object

Static methods to write and read compressed forms of numbers to DataOut and DataIn interfaces. Format written is platform independent like the Data* interfaces and must remain fixed once a product is shipped. If a different format is required then write a new set of methods, e.g. writeInt2. The formats defined by stored format identifiers are implicitly dependent on these formats not changing.

Field Summary

Fields

Modifier and Type	Field and Description
static int	MAX_COMPRESSED_INT_ONE_BYTE
static int	MAX_COMPRESSED_INT_TWO_BYTES
static int	MAX_INT_STORED_SIZE
static int	MAX_LONG_STORED_SIZE

Constructor Summary

Constructors

Constructor and Description
CompressedNumber()

Method Summary

Modifier and Type	Method and Description
static int	readInt(byte[] data, int offset)
static int	readInt(java.io.DataInput in) Read an integer previously written by writeInt().
static int	readInt(java.io.InputStream in) Read an integer previously written by writeInt().
static long	readLong(byte[] data, int offset)
static long	readLong(java.io.DataInput in) Read a long previously written by writeLong().
static long	readLong(java.io.InputStream in) Read a long previously written by writeLong().
static int	sizeInt(int value) Return the number of bytes that would be written by a writeInt call
static int	sizeLong(long value)
static int	writeInt(java.io.DataOutput out, int value) Write a compressed integer only supporting signed values.
static int	writeInt(java.io.OutputStream out, int value) Write a compressed integer directly to an OutputStream.
static int	writeLong(java.io.DataOutput out, long value) Write a compressed long only supporting signed values.
static int	writeLong(java.io.OutputStream out, long value) Write a compressed integer only supporting signed values.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

MAX_INT_STORED_SIZE

public static final int MAX_INT_STORED_SIZE

See Also:

Constant Field Values

MAX_LONG_STORED_SIZE

public static final int MAX_LONG_STORED_SIZE

See Also:

Constant Field Values

MAX_COMPRESSED_INT_ONE_BYTE

public static final int MAX_COMPRESSED_INT_ONE_BYTE

See Also:

Constant Field Values

MAX_COMPRESSED_INT_TWO_BYTES

public static final int MAX_COMPRESSED_INT_TWO_BYTES

See Also:

Constant Field Values

Constructor Detail

CompressedNumber

public CompressedNumber()

Method Detail

writeInt

public static final int writeInt(java.io.DataOutput out,
                                 int value)
                          throws java.io.IOException

Write a compressed integer only supporting signed values. Formats are (with x representing value bits):

                1 Byte - 00xxxxxx                              Represents the value <= 63 (0x3f)
                2 Byte - 01xxxxxx xxxxxxxx                     Represents the value > 63 && <= 16383 (0x3fff)
                4 byte - 1xxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx   Represents the value > 16383 && <= MAX_INT
                

Throws:

java.io.IOException - value is negative or an exception was thrown by a method on out.

writeInt

public static final int writeInt(java.io.OutputStream out,
                                 int value)
                          throws java.io.IOException

Write a compressed integer directly to an OutputStream.

Throws:

java.io.IOException - an exception was thrown by a method on in.

readInt

public static final int readInt(java.io.DataInput in)
                         throws java.io.IOException

Read an integer previously written by writeInt().

Throws:

java.io.IOException - an exception was thrown by a method on in.

readInt

public static final int readInt(java.io.InputStream in)
                         throws java.io.IOException

Read an integer previously written by writeInt().

Throws:

java.io.IOException - an exception was thrown by a method on in.

readInt

public static final int readInt(byte[] data,
                                int offset)

sizeInt

public static final int sizeInt(int value)

Return the number of bytes that would be written by a writeInt call

writeLong

public static final int writeLong(java.io.DataOutput out,
                                  long value)
                           throws java.io.IOException

Write a compressed long only supporting signed values. Formats are (with x representing value bits):

                2 byte - 00xxxxxx xxxxxxxx                     Represents the value <= 16383 (0x3fff)
                4 byte - 01xxxxxx xxxxxxxx xxxxxxxx xxxxxxxx   Represents the value > 16383  && <= 0x3fffffff
                8 byte - 1xxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx   Represents the value > 0x3fffffff && <= MAX_LONG
                

Throws:

java.io.IOException - value is negative or an exception was thrown by a method on out.

writeLong

public static final int writeLong(java.io.OutputStream out,
                                  long value)
                           throws java.io.IOException

Write a compressed integer only supporting signed values.

Throws:

java.io.IOException - value is negative or an exception was thrown by a method on out.

readLong

public static final long readLong(java.io.DataInput in)
                           throws java.io.IOException

Read a long previously written by writeLong().

Throws:

java.io.IOException - an exception was thrown by a method on in.

readLong

public static final long readLong(java.io.InputStream in)
                           throws java.io.IOException

Read a long previously written by writeLong().

Throws:

java.io.IOException - an exception was thrown by a method on in.

readLong

public static final long readLong(byte[] data,
                                  int offset)

sizeLong

public static final int sizeLong(long value)