content: /*************************************************************************
   *  Compilation:  javac BinaryStdIn.java
   *  Execution:    java BinaryStdIn < input > output
   *  
   *  Supports reading binary data from standard input.
   *
   *  % java BinaryStdIn < input.jpg > output.jpg
   *  % diff input.jpg output.jpg
   *
   *************************************************************************/
  
  import java.io.BufferedInputStream;
  import java.io.IOException;
  
  /**
   *  <i>Binary standard input</i>. This class provides methods for reading
   *  in bits from standard input, either one bit at a time (as a <tt>boolean</tt>),
   *  8 bits at a time (as a <tt>byte</tt> or <tt>char</tt>),
   *  16 bits at a time (as a <tt>short</tt>), 32 bits at a time
   *  (as an <tt>int</tt> or <tt>float</tt>), or 64 bits at a time (as a
   *  <tt>double</tt> or <tt>long</tt>).
   *  <p>
   *  All primitive types are assumed to be represented using their 
   *  standard Java representations, in big-endian (most significant
   *  byte first) order.
   *  <p>
   *  The client should not intermix calls to <tt>BinaryStdIn</tt> with calls
   *  to <tt>StdIn</tt> or <tt>System.in</tt>;
   *  otherwise unexpected behavior will result.
   */
  public final class BinaryStdIn {
      private static BufferedInputStream in = new BufferedInputStream(System.in);
      private static final int EOF = -1;    // end of file
  
      private static int buffer;            // one character buffer
      private static int N;                 // number of bits left in buffer
  
      // static initializer
      static { fillBuffer(); }
  
      // singleton pattern - can't instantiate
      private BinaryStdIn() { }
  
      private static void fillBuffer() {
          try { buffer = in.read(); N = 8; }
          catch (IOException e) { System.out.println("EOF"); buffer = EOF; N = -1; }
      }
  
     /**
       * Close this input stream and release any associated system resources.
       */
      public static void close() {
          try {
              in.close();
          }
          catch (IOException e) {
              e.printStackTrace();
              throw new RuntimeException("Could not close BinaryStdIn");
          }
      }
  
     /**
       * Returns true if standard input is empty.
       * @return true if and only if standard input is empty
       */
      public static boolean isEmpty() {
          return buffer == EOF;
      }
  
     /**
       * Read the next bit of data from standard input and return as a boolean.
       * @return the next bit of data from standard input as a <tt>boolean</tt>
       * @throws RuntimeException if standard input is empty
       */
      public static boolean readBoolean() {
          if (isEmpty()) throw new RuntimeException("Reading from empty input stream");
          N--;
          boolean bit = ((buffer >> N) & 1) == 1;
          if (N == 0) fillBuffer();
          return bit;
      }
  
     /**
       * Read the next 8 bits from standard input and return as an 8-bit char.
       * Note that <tt>char</tt> is a 16-bit type;
       * to read the next 16 bits as a char, use <tt>readChar(16)</tt>
       * @return the next 8 bits of data from standard input as a <tt>char</tt>
       * @throws RuntimeException if there are fewer than 8 bits available on standard input
       */
      public static char readChar() {
          if (isEmpty()) throw new RuntimeException("Reading from empty input stream");
  
          // special case when aligned byte
          if (N == 8) {
              int x = buffer;
              fillBuffer();
              return (char) (x & 0xff);
          }
  
          // combine last N bits of current buffer with first 8-N bits of new buffer
          int x = buffer;
          x <<= (8-N);
          int oldN = N;
          fillBuffer();
          if (isEmpty()) throw new RuntimeException("Reading from empty input stream");
          N = oldN;
          x |= (buffer >>> N);
          return (char) (x & 0xff);
          // the above code doesn't quite work for the last character if N = 8
          // because buffer will be -1
      }
  
     /**
       * Read the next r bits from standard input and return as an r-bit character.
       * @param r number of bits to read.
       * @return the next r bits of data from standard input as a <tt>char</tt>
       * @throws RuntimeException if there are fewer than r bits available on standard input
       * @throws RuntimeException unless 1 &le; r &le; 16
       */
      public static char readChar(int r) {
          if (r < 1 || r > 16) throw new RuntimeException("Illegal value of r = " + r);
  
          // optimize r = 8 case
          if (r == 8) return readChar();
  
          char x = 0;
          for (int i = 0; i < r; i++) {
              x <<= 1;
              boolean bit = readBoolean();
              if (bit) x |= 1;
          }
          return x;
      }
  
     /**
       * Read the remaining bytes of data from standard input and return as a string. 
       * @return the remaining bytes of data from standard input as a <tt>String</tt>
       * @throws RuntimeException if standard input is empty or if the number of bits
       * available on standard input is not a multiple of 8 (byte-aligned)
       */
      public static String readString() {
          if (isEmpty()) throw new RuntimeException("Reading from empty input stream");
  
          StringBuilder sb = new StringBuilder();
          while (!isEmpty()) {
              char c = readChar();
              sb.append(c);
          }
          return sb.toString();
      }
  
  
     /**
       * Read the next 16 bits from standard input and return as a 16-bit short.
       * @return the next 16 bits of data from standard input as a <tt>short</tt>
       * @throws RuntimeException if there are fewer than 16 bits available on standard input
       */
      public static short readShort() {
          short x = 0;
          for (int i = 0; i < 2; i++) {
              char c = readChar();
              x <<= 8;
              x |= c;
          }
          return x;
      }
  
     /**
       * Read the next 32 bits from standard input and return as a 32-bit int.
       * @return the next 32 bits of data from standard input as a <tt>int</tt>
       * @throws RuntimeException if there are fewer than 32 bits available on standard input
       */
      public static int readInt() {
          int x = 0;
          for (int i = 0; i < 4; i++) {
              char c = readChar();
              x <<= 8;
              x |= c;
          }
          return x;
      }
  
     /**
       * Read the next r bits from standard input and return as an r-bit int.
       * @param r number of bits to read.
       * @return the next r bits of data from standard input as a <tt>int</tt>
       * @throws RuntimeException if there are fewer than r bits available on standard input
       * @throws RuntimeException unless 1 &le; r &le; 32
       */
      public static int readInt(int r) {
          if (r < 1 || r > 32) throw new RuntimeException("Illegal value of r = " + r);
  
          // optimize r = 32 case
          if (r == 32) return readInt();
  
          int x = 0;
          for (int i = 0; i < r; i++) {
              x <<= 1;
              boolean bit = readBoolean();
              if (bit) x |= 1;
          }
          return x;
      }
  
     /**
       * Read the next 64 bits from standard input and return as a 64-bit long.
       * @return the next 64 bits of data from standard input as a <tt>long</tt>
       * @throws RuntimeException if there are fewer than 64 bits available on standard input
       */
      public static long readLong() {
          long x = 0;
          for (int i = 0; i < 8; i++) {
              char c = readChar();
              x <<= 8;
              x |= c;
          }
          return x;
      }
  
  
     /**
       * Read the next 64 bits from standard input and return as a 64-bit double.
       * @return the next 64 bits of data from standard input as a <tt>double</tt>
       * @throws RuntimeException if there are fewer than 64 bits available on standard input
       */
      public static double readDouble() {
          return Double.longBitsToDouble(readLong());
      }
  
     /**
       * Read the next 32 bits from standard input and return as a 32-bit float.
       * @return the next 32 bits of data from standard input as a <tt>float</tt>
       * @throws RuntimeException if there are fewer than 32 bits available on standard input
       */
      public static float readFloat() {
          return Float.intBitsToFloat(readInt());
      }
  
  
     /**
       * Read the next 8 bits from standard input and return as an 8-bit byte.
       * @return the next 8 bits of data from standard input as a <tt>byte</tt>
       * @throws RuntimeException if there are fewer than 8 bits available on standard input
       */
      public static byte readByte() {
          char c = readChar();
          byte x = (byte) (c & 0xff);
          return x;
      }
      
     /**
       * Test client. Reads in a binary input file from standard input and writes
       * it to standard output.
       */
      public static void main(String[] args) {
  
          // read one 8-bit char at a time
          while (!BinaryStdIn.isEmpty()) {
              char c = BinaryStdIn.readChar();
              BinaryStdOut.write(c);
          }
          BinaryStdOut.flush();
      }
  }
  