UnsignedLexVarint

java.lang.Object
- brown.tracingplane.atomlayer.UnsignedLexVarint

```
public class UnsignedLexVarint
extends java.lang.Object
```
Unsigned 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.

For example, consider the integers 130, 257, and 16385. Numerically, 130 < 257 < 16385. Consider their binary encodings using protobuf-style varints:
- 130: 1000 0100 0000 0001
- 257: 1000 0010 0000 0010
- 16385: 1000 0001 1000 0000 0000 0001
The lexicographical comparison of these encodings will give us 16385 < 257 < 130.

This happens because the first bit of each byte of a protobuf-style varint says whether there are more bytes in the binary representation (1 means 'more bytes', 0 means 'no more bytes'). Also, protobuf-style varints switch the order of bytes of the encoded integer (that is, least- significant bytes go first).

To make binary encodings lexicographically comparable, we must place all of the 'more bytes' prefixes at the start of the encoded representation, and encode bytes with most-significant bytes first.

For unsigned 64-bit integers, values in the range [0, 2^7) use 1 byte; [2^7, 2^14) use 2 bytes, [2^14, 2^21) use 3 bytes, and so on. Negative 64-bit unsigned integers use 9 bytes. Negative 32-bit unsigned integeers use 5 bytes.
Author:

jon

Constructor Summary

Constructors
Constructor and Description

UnsignedLexVarint()

Constructors
Constructor and Description
`UnsignedLexVarint()`

Method Summary

All Methods Static Methods Concrete Methods
Modifier and Type	Method and Description
`static int`	`encodedLength(int value)`
`static int`	`encodedLength(long value)`
`static void`	`main(java.lang.String[] args)`
`static int`	`readLexVarUInt32(java.nio.ByteBuffer buf)` Reads a lexvar uint32 from the specified buf, advancing the buf's position
`static int`	`readLexVarUInt32(java.nio.ByteBuffer buf, int position)` Reads a lexvar uint32 from the specified buf without advancing the buf's position
`static long`	`readLexVarUInt64(java.nio.ByteBuffer buf)` Reads a varint that is lexicographically comparable with other varints and advance the buf's position
`static long`	`readLexVarUInt64(java.nio.ByteBuffer buf, int position)` Reads a varint that is lexicographically comparable with other varints without advancing the buf's position
`static long`	`readReverseLexVarUInt64(java.nio.ByteBuffer buf)` Reads a varint that is reverse lexicographically comparable with other varints and advance the buf's position
`static long`	`readReverseLexVarUInt64(java.nio.ByteBuffer buf, int position)` Reads a varint that is reverse lexicographically comparable with other varints without advancing the buf's position
`static int`	`writeLexVarUInt32(java.nio.ByteBuffer buf, int value)`
`static int`	`writeLexVarUInt64(java.nio.ByteBuffer buf, long value)`
`static int`	`writeReverseLexVarUInt32(java.nio.ByteBuffer buf, int value)`
`static int`	`writeReverseLexVarUInt64(java.nio.ByteBuffer buf, long value)`
`static byte[]`	`writeVarUInt32(int value)` Returns the byte representation of the provided 32 bit unsigned integer encoded as a lexicographically comparable varint
`static byte[]`	`writeVarUInt64(long value)` Returns the byte representation of the provided 64 bit unsigned integer encoded as a lexicographically comparable varint

Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - UnsignedLexVarint
```
public UnsignedLexVarint()
```
- Method Detail
  - main
```
public static void main(java.lang.String[] args)
```
  - 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 [0, 2^7) use 1 byte; [2^7, 2^14) use 2 bytes, and so on. Negative values use 5 bytes.
  - 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 [0, 2^7) use 1 byte; [2^7, 2^14) use 2 bytes, and so on. Negative values use 9 bytes.
  - writeLexVarUInt32
```
public static int writeLexVarUInt32(java.nio.ByteBuffer buf,
                                    int value)
```
  - writeReverseLexVarUInt32
```
public static int writeReverseLexVarUInt32(java.nio.ByteBuffer buf,
                                           int value)
```
  - writeLexVarUInt64
```
public static int writeLexVarUInt64(java.nio.ByteBuffer buf,
                                    long value)
```
  - writeReverseLexVarUInt64
```
public static int writeReverseLexVarUInt64(java.nio.ByteBuffer buf,
                                           long value)
```
  - readLexVarUInt32
```
public static int readLexVarUInt32(java.nio.ByteBuffer buf)
                            throws AtomLayerException
```
    Reads a lexvar uint32 from the specified buf, advancing the buf's position
    
    Throws:
    
    AtomLayerException
  - readLexVarUInt32
```
public static int readLexVarUInt32(java.nio.ByteBuffer buf,
                                   int position)
                            throws AtomLayerException
```
    Reads a lexvar uint32 from the specified buf without advancing the buf's position
    
    Throws:
    
    AtomLayerException
  - readLexVarUInt64
```
public static long readLexVarUInt64(java.nio.ByteBuffer buf)
                             throws AtomLayerException
```
    Reads a varint that is lexicographically comparable with other varints and advance the buf's position
    
    Throws:
    
    AtomLayerException
  - readReverseLexVarUInt64
```
public static long readReverseLexVarUInt64(java.nio.ByteBuffer buf)
                                    throws AtomLayerException
```
    Reads a varint that is reverse lexicographically comparable with other varints and advance the buf's position
    
    Throws:
    
    AtomLayerException
  - readLexVarUInt64
```
public static long readLexVarUInt64(java.nio.ByteBuffer buf,
                                    int position)
                             throws AtomLayerException
```
    Reads a varint that is lexicographically comparable with other varints without advancing the buf's position
    
    Throws:
    
    AtomLayerException
  - readReverseLexVarUInt64
```
public static long readReverseLexVarUInt64(java.nio.ByteBuffer buf,
                                           int position)
                                    throws AtomLayerException
```
    Reads a varint that is reverse lexicographically comparable with other varints without advancing the buf's position
    
    Throws:
    
    AtomLayerException
  - writeVarUInt32
```
public static byte[] writeVarUInt32(int value)
```
    Returns the byte representation of the provided 32 bit unsigned integer encoded as a lexicographically comparable varint
  - writeVarUInt64
```
public static byte[] writeVarUInt64(long value)
```
    Returns the byte representation of the provided 64 bit unsigned integer encoded as a lexicographically comparable varint

Class UnsignedLexVarint

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

UnsignedLexVarint

Method Detail

main

encodedLength

encodedLength

writeLexVarUInt32

writeReverseLexVarUInt32

writeLexVarUInt64

writeReverseLexVarUInt64

readLexVarUInt32

readLexVarUInt32

readLexVarUInt64

readReverseLexVarUInt64

readLexVarUInt64

readReverseLexVarUInt64

writeVarUInt32

writeVarUInt64