import java.io.*;

/**
 * Class which performs both the arithmetic encoding and decoding algorithms, using
 * integer implementation, adaptation, and contexts.
 * 
 * @author Amanda Askew & Dane Barney
 * @version 2003.09.11
 */
public class ArithmeticCoder {
    private final long UPPER_BOUND = (long)Integer.MAX_VALUE*2+1;
    private final long MIDDLE_BOUND = UPPER_BOUND/2+1;
    private final long ONE_4TH_BOUND = MIDDLE_BOUND/2;
    private final long THREE_4TH_BOUND = ONE_4TH_BOUND*3;

    private long L, R, T;
    private int C;
     
    public ArithmeticCoder() {
        // initialize L and R, the upper and lower bounds of the interval
        L = 0;
        R = UPPER_BOUND;
        T = 0; // the unsigned value of the tag buffer (used only for decoding)
        C = 0; // middle half scaling counter (used only for encoding)
    }
    
    /**
     * Arithmetically encodes one value.
     * 
     * @param val       the value to encode
     * @param context   the context associated with this value
     * @param out       the outstream to write to
     */
    public void encodeValue(int val, Context context, BitWriter out) throws IOException {
        assert (val >= 0);
        
        out.writeBit(val);
    }
    
    
    
    /**
     * The first step in decoding. This shifts in the first 32-bits (the size of type "int")
     * into the tag, so that decoding can begin.
     */
    public void initializeTag(BitReader in) throws IOException {
        
    }
    
    /**
     * Arithmetically decodes and returns one value.
     * 
     * @param context   the context associated with this value
     * @param in        the bitstream being read from
     * @return          the decoded value
     */
    public int decodeValue(Context context, BitReader in) throws IOException {
        
        return in.readBit(true);
    }

   
    /**
     *  Clean up.
     */
    public void finishEncode(BitWriter out) {
    
    }

}