ArithmeticDecoder (MG4J (big) 5.4.4)

java.lang.Object
- it.unimi.di.big.mg4j.io.ArithmeticDecoder

```
public final class ArithmeticDecoder
extends Object
```
An arithmetic decoder.
This class provides an arithmetic decoder. The input of the coder is an InputBitStream. You must first create a decoder specifying the number of input symbols, then call decode(InputBitStream) for all symbols to be decoded, and finally flush(InputBitStream). This last operation reads the bits flushed by ArithmeticCoder.flush(OutputBitStream). Thereafter, exactly BITS excess bits will be present in the current window of the decoder. You can get them using getWindow().
The code is inspired by the arithmetic decoder by John Carpinelli, Radford M. Neal, Wayne Salamonsen and Lang Stuiver, which is in turn based on Arithmetic Coding Revisited, by Alistair Moffat, Radford M. Neal and Ian H. Witten (Proc. IEEE Data Compression Conference, Snowbird, Utah, March 1995).

Since:

0.1

Author:

Sebastiano Vigna

See Also:

ArithmeticCoder

Field Summary

Fields
Modifier and Type Field Description

static int BITS
Number of bits used by the decoder.

Constructor Summary

Constructors
Constructor Description

ArithmeticDecoder(int n)
Creates a new decoder.

Method Summary

Modifier and Type	Method	Description
`int`	`decode(InputBitStream ibs)`	Decodes a symbol.
`void`	`flush(InputBitStream ibs)`	Flushes (reads) the disambiguating bits.
`long`	`getWindow()`	Returns the current bit stream window.

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

- Field Detail
  - BITS
```
public static final int BITS
```
    Number of bits used by the decoder.
    
    See Also:
    
    Constant Field Values
- Constructor Detail
  - ArithmeticDecoder
```
public ArithmeticDecoder(int n)
```
    Creates a new decoder.
    
    Parameters:
    
    n - number of symbols used by the decoder.
- Method Detail
  - decode
```
public int decode(InputBitStream ibs)
           throws IOException
```
    Decodes a symbol.
    
    Parameters:
    
    ibs - the input stream.
    
    Returns:
    
    the next symbol encoded.
    
    Throws:
    
    IOException - if ibs does.
  - flush
```
public void flush(InputBitStream ibs)
           throws IOException
```
    Flushes (reads) the disambiguating bits.
    This method must be called when all symbols have been decoded. After the call, exactly BITS excess bits will be present in the current window of the decoder. You can get them using getWindow(); usually you will then unget them to the bit stream.
    
    Parameters:
    
    ibs - the input stream.
    
    Throws:
    
    IOException - if ibs does.
  - getWindow
```
public long getWindow()
```
    Returns the current bit stream window.
    
    Returns:
    
    the current bit stream window in the lower BITS bits.