brown.tracingplane.atomlayer

Class SignedLexVarint

java.lang.Object

brown.tracingplane.atomlayer.SignedLexVarint

public class SignedLexVarint
extends java.lang.Object

Signed varint (32 bit and 64 bit) that is encoded in such a way that the lexicographic comparison of the binary encoding is consistent with the numeric comparison of the numeric values. This is like unsigned varints, but with the following: - the first bit is a sign bit with 0 negative and 1 positive - negative values use 0 to indicate additional bytes; positive values use 1 So, for example, we get the following encodings: Long.MIN_VALUE: 0000 0000 0000 0000 0000 0000 ... (9 bytes worth of zeros) -65: 0011 1111 1011 1111 -64: 0100 0000 -19: 0110 1101 -4: 0111 1100 -1: 0111 1111 0: 1000 0000 1: 1000 0001 19: 1001 0011 63: 1011 1111 64: 1100 0000 0100 0000 LONG.MAX_VALUE: 1111 1111 1111 1111 1111 1111 ... (9 bytes worth of ones)

Constructor Summary

Constructors

Constructor and Description
SignedLexVarint()

Method Summary

Modifier and Type	Method and Description
static int	encodedLength(int value)
static int	encodedLength(long value)
static int	readLexVarInt32(java.nio.ByteBuffer buf) Interprets the next bytes of buf as a lexicographically comparable signed 32-bit integer.
static long	readLexVarInt64(java.nio.ByteBuffer buf) Interprets the next bytes of buf as a lexicographically comparable signed 64-bit integer.
static int	readReverseLexVarInt32(java.nio.ByteBuffer buf) Interprets the next bytes of buf as a lexicographically comparable signed 32-bit integer.
static long	readReverseLexVarInt64(java.nio.ByteBuffer buf) Interprets the next bytes of buf as a lexicographically comparable signed 64-bit integer.
static int	writeLexVarInt32(java.nio.ByteBuffer buf, int value)
static int	writeLexVarInt64(java.nio.ByteBuffer buf, long value)
static int	writeReverseLexVarInt32(java.nio.ByteBuffer buf, int value)
static int	writeReverseLexVarInt64(java.nio.ByteBuffer buf, long value)
static byte[]	writeVarInt32(int value)
static byte[]	writeVarInt64(long value)

Methods inherited from class java.lang.Object

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

Constructor Detail

SignedLexVarint

public SignedLexVarint()

Method Detail

encodedLength

public static int encodedLength(int value)

Parameters:

value - Any integer value

Returns:

the length of the encoded representation of this value. Values in the range [-2^6, 2^6) use 1 byte; [-2^12, -2^6) and [2^6, 2^12) use 2 bytes, and so on

encodedLength

public static int encodedLength(long value)

Parameters:

value - Any long value

Returns:

the length of the encoded representation of this value. Values in the range [-2^6, 2^6) use 1 byte; [-2^12, -2^6) and [2^6, 2^12) use 2 bytes, and so on

writeLexVarInt32

public static int writeLexVarInt32(java.nio.ByteBuffer buf,
                                   int value)

writeReverseLexVarInt32

public static int writeReverseLexVarInt32(java.nio.ByteBuffer buf,
                                          int value)

writeLexVarInt64

public static int writeLexVarInt64(java.nio.ByteBuffer buf,
                                   long value)

writeReverseLexVarInt64

public static int writeReverseLexVarInt64(java.nio.ByteBuffer buf,
                                          long value)

readLexVarInt32

public static int readLexVarInt32(java.nio.ByteBuffer buf)
                           throws AtomLayerException

Interprets the next bytes of buf as a lexicographically comparable signed 32-bit integer. Reads up to 5 bytes from buf to decode the value.

Parameters:

buf - a buffer

Returns:

a signed integer read from buf

Throws:

AtomLayerException - if the next bytes are invalid when interpreted as a lexicographically comparable varint

readReverseLexVarInt32

public static int readReverseLexVarInt32(java.nio.ByteBuffer buf)
                                  throws AtomLayerException

Interprets the next bytes of buf as a lexicographically comparable signed 32-bit integer. Reads up to 5 bytes from buf to decode the value. Interprets them as a reverse int, eg, s.t. the lexicographical comparison is reversed

Parameters:

buf - a buffer

Returns:

a signed integer read from buf

Throws:

AtomLayerException - if the next bytes are invalid when interpreted as a lexicographically comparable varint

readLexVarInt64

public static long readLexVarInt64(java.nio.ByteBuffer buf)
                            throws AtomLayerException

Interprets the next bytes of buf as a lexicographically comparable signed 64-bit integer. Reads up to 9 bytes from buf to decode the value.

Parameters:

buf - a buffer

Returns:

a signed long read from buf

Throws:

AtomLayerException - if the next bytes are invalid when interpreted as a lexicographically comparable varint

readReverseLexVarInt64

public static long readReverseLexVarInt64(java.nio.ByteBuffer buf)
                                   throws AtomLayerException

Interprets the next bytes of buf as a lexicographically comparable signed 64-bit integer. Reads up to 9 bytes from buf to decode the value. Interprets them as a reverse int, eg, s.t. the lexicographical comparison is reversed

Parameters:

buf - a buffer

Returns:

a signed long read from buf

Throws:

AtomLayerException - if the next bytes are invalid when interpreted as a lexicographically comparable varint

writeVarInt32

public static byte[] writeVarInt32(int value)

Parameters:

value - a 32-bit signed integer

Returns:

value encoded as a lexicographically-comparable variable-length integer.

writeVarInt64

public static byte[] writeVarInt64(long value)

Parameters:

value - a 64-bit signed long

Returns:

value encoded as a lexicographically-comparable variable-length long integer.