import java.io.*;
/**
 * Classe permettant la lecture dans un flot bit à bit
 * @author Forax the best of us
 * @version 1.0
 */
public class BitInputStream extends FilterInputStream {  
  int bits;
  int mask;
  
  public BitInputStream(InputStream in) {
    super(in);
  }
 /**
  * Reads the next bit from this input stream. The value is returned as an
  * int in the range 0 to 1. If no bit is available because the end of the stream
  * has been reached, the value -1 is returned.
  * This method blocks until input data is available, the end of the stream
  * is detected, or an exception is thrown. 
  */
  public int readBit() throws IOException {
    int bits;
    int mask=this.mask;

    if (mask==0) {
      bits=read();
      if (bits==-1)
        return -1;

      this.bits=bits;
      mask=0x80;
    }
    else {
      bits=this.bits;
    }

    if ((bits & mask)==0) {
      this.mask=mask>>1;
      return 0;
    }
    else {
      this.mask=mask>>1;
      return 1;
    }
  }

}