//
   //  ========================================================================
   //  Copyright (c) 1995-2013 Mort Bay Consulting Pty. Ltd.
   //  ------------------------------------------------------------------------
   //  All rights reserved. This program and the accompanying materials
   //  are made available under the terms of the Eclipse Public License v1.0
   //  and Apache License v2.0 which accompanies this distribution.
   //
   //      The Eclipse Public License is available at
  //      http://www.eclipse.org/legal/epl-v10.html
  //
  //      The Apache License v2.0 is available at
  //      http://www.opensource.org/licenses/apache2.0.php
  //
  //  You may elect to redistribute this code under either of these licenses.
  //  ========================================================================
  //
  
  package org.eclipse.jetty.util;
  
  import java.io.File;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  import java.io.RandomAccessFile;
  import java.nio.Buffer;
  import java.nio.ByteBuffer;
  import java.nio.MappedByteBuffer;
  import java.nio.channels.FileChannel;
  import java.nio.channels.FileChannel.MapMode;
  import java.nio.charset.Charset;
  
  
  /* ------------------------------------------------------------------------------- */
  /**
   * Buffer utility methods.
   *
   * These utility methods facilitate the usage of NIO {@link ByteBuffer}'s in a more flexible way.
   * The standard {@link ByteBuffer#flip()} assumes that once flipped to flush a buffer,
   * that it will be completely emptied before being cleared ready to be filled again.
   * The {@link #flipToFill(ByteBuffer)} and {@link #flipToFlush(ByteBuffer, int)} methods provided here
   * do not assume that the buffer is empty and will preserve content when flipped.
   * <p>
   * ByteBuffers can be considered in one of two modes: Flush mode where valid content is contained between
   * position and limit which is consumed by advancing the position; and Fill mode where empty space is between
   * the position and limit, which is filled by advancing the position.   In fill mode, there may be valid data
   * in the buffer before the position and the start of this data is given by the return value of {@link #flipToFill(ByteBuffer)}
   * <p>
   * A typical pattern for using the buffers in this style is:
   * <blockquote><pre>
   *    ByteBuffer buf = BufferUtil.allocate(4096);
   *    while(in.isOpen())
   *    {
   *        int pos=BufferUtil.flipToFill(buf);
   *        if (in.read(buf)<0)
   *          break;
   *        BufferUtil.flipToFlush(buf,pos);
   *        out.write(buf);
   *    }</pre></blockquote>
   */
  public class BufferUtil
  {
      static final byte SPACE = 0x20;
      static final byte MINUS = '-';
      static final byte[] DIGIT =
      { (byte)'0', (byte)'1', (byte)'2', (byte)'3', (byte)'4', (byte)'5', (byte)'6', (byte)'7', (byte)'8', (byte)'9', (byte)'A', (byte)'B', (byte)'C', (byte)'D',
              (byte)'E', (byte)'F' };
  
      public static final ByteBuffer EMPTY_BUFFER = ByteBuffer.wrap(new byte[0]);
  
      /* ------------------------------------------------------------ */
      /** Allocate ByteBuffer in flush mode.
       * The position and limit will both be zero, indicating that the buffer is
       * empty and must be flipped before any data is put to it.
       * @param capacity
       * @return Buffer
       */
      public static ByteBuffer allocate(int capacity)
      {
          ByteBuffer buf = ByteBuffer.allocate(capacity);
          buf.limit(0);
          return buf;
      }
  
      /* ------------------------------------------------------------ */
      /** Allocate ByteBuffer in flush mode.
       * The position and limit will both be zero, indicating that the buffer is
       * empty and must be flipped before any data is put to it.
       * @param capacity
       * @return Buffer
       */
      public static ByteBuffer allocateDirect(int capacity)
      {
          ByteBuffer buf = ByteBuffer.allocateDirect(capacity);
          buf.limit(0);
          return buf;
      }
  
  
     /* ------------------------------------------------------------ */
     /** Clear the buffer to be empty in flush mode.
      * The position and limit are set to 0;
      * @param buffer The buffer to clear.
      */
     public static void clear(ByteBuffer buffer)
     {
         if (buffer!=null)
         {
             buffer.position(0);
             buffer.limit(0);
         }
     }
 
     /* ------------------------------------------------------------ */
     /** Clear the buffer to be empty in fill mode.
      * The position is set to 0 and the limit is set to the capacity.
      * @param buffer The buffer to clear.
      */
     public static void clearToFill(ByteBuffer buffer)
     {
         if (buffer!=null)
         {
             buffer.position(0);
             buffer.limit(buffer.capacity());
         }
     }
 
     /* ------------------------------------------------------------ */
     /** Flip the buffer to fill mode.
      * The position is set to the first unused position in the buffer
      * (the old limit) and the limit is set to the capacity.
      * If the buffer is empty, then this call is effectively {@link #clearToFill(ByteBuffer)}.
      * If there is no unused space to fill, a {@link ByteBuffer#compact()} is done to attempt
      * to create space.
      * <p>
      * This method is used as a replacement to {@link ByteBuffer#compact()}.
      *
      * @param buffer The buffer to flip
      * @return The position of the valid data before the flipped position. This value should be
      * passed to a subsequent call to {@link #flipToFlush(ByteBuffer, int)}
      */
     public static int flipToFill(ByteBuffer buffer)
     {
         int position=buffer.position();
         int limit=buffer.limit();
         if (position==limit)
         {
             buffer.position(0);
             buffer.limit(buffer.capacity());
             return 0;
         }
 
         int capacity=buffer.capacity();
         if (limit==capacity)
         {
             buffer.compact();
             return 0;
         }
 
         buffer.position(limit);
         buffer.limit(capacity);
         return position;
     }
 
 
     /* ------------------------------------------------------------ */
     /** Flip the buffer to Flush mode.
      * The limit is set to the first unused byte(the old position) and
      * the position is set to the passed position.
      * <p>
      * This method is used as a replacement of {@link Buffer#flip()}.
      * @param buffer the buffer to be flipped
      * @param position The position of valid data to flip to. This should
      * be the return value of the previous call to {@link #flipToFill(ByteBuffer)}
      */
     public static void flipToFlush(ByteBuffer buffer,int position)
     {
         buffer.limit(buffer.position());
         buffer.position(position);
     }
 
 
     /* ------------------------------------------------------------ */
     /** Convert a ByteBuffer to a byte array.
      * @param buffer The buffer to convert in flush mode. The buffer is not altered.
      * @return An array of bytes duplicated from the buffer.
      */
     public static byte[] toArray(ByteBuffer buffer)
     {
         byte[] to = new byte[buffer.remaining()];
         if (buffer.hasArray())
         {
             byte[] array = buffer.array();
             System.arraycopy(array,buffer.arrayOffset()+buffer.position(),to,0,to.length);
         }
         else
             buffer.slice().get(to);
         return to;
     }
 
     /* ------------------------------------------------------------ */
     /** Check for an empty or null buffer.
      * @param buf the buffer to check
      * @return true if the buffer is null or empty.
      */
     public static boolean isEmpty(ByteBuffer buf)
     {
         return buf==null || buf.remaining()==0;
     }
 
     /* ------------------------------------------------------------ */
     /** Check for a non null and non empty buffer.
      * @param buf the buffer to check
      * @return true if the buffer is not null and not empty.
      */
     public static boolean hasContent(ByteBuffer buf)
     {
         return buf!=null && buf.remaining()>0;
     }
 
     /* ------------------------------------------------------------ */
     /** Check for a non null and full buffer.
      * @param buf the buffer to check
      * @return true if the buffer is not null and the limit equals the capacity.
      */
     public static boolean isFull(ByteBuffer buf)
     {
         return buf!=null && buf.limit()==buf.capacity();
     }
 
     /* ------------------------------------------------------------ */
     /** Get remaining from null checked buffer
      * @param buffer The buffer to get the remaining from, in flush mode.
      * @return 0 if the buffer is null, else the bytes remaining in the buffer.
      */
     public static int length(ByteBuffer buffer)
     {
         return buffer==null?0:buffer.remaining();
     }
 
     /* ------------------------------------------------------------ */
     /** Get the space from the limit to the capacity
      * @param buffer
      * @return space
      */
     public static int space(ByteBuffer buffer)
     {
         if (buffer==null)
             return 0;
         return buffer.capacity()-buffer.limit();
     }
 
     /* ------------------------------------------------------------ */
     /** Compact the buffer
      * @param buffer
      * @return true if the compact made a full buffer have space
      */
     public static boolean compact(ByteBuffer buffer)
     {
         boolean full=buffer.limit()==buffer.capacity();
         buffer.compact().flip();
         return full && buffer.limit()<buffer.capacity();
     }
 
     /* ------------------------------------------------------------ */
     /**
      * Put data from one buffer into another, avoiding over/under flows
      * @param from Buffer to take bytes from in flush mode
      * @param to Buffer to put bytes to in fill mode.
      * @return number of bytes moved
      */
     public static int put(ByteBuffer from, ByteBuffer to)
     {
         int put;
         int remaining=from.remaining();
         if (remaining>0)
         {
             if (remaining<=to.remaining())
             {
                 to.put(from);
                 put=remaining;
                 from.position(0);
                 from.limit(0);
             }
             else if (from.hasArray())
             {
                 put=to.remaining();
                 to.put(from.array(),from.arrayOffset()+from.position(),put);
                 from.position(from.position()+put);
             }
             else
             {
                 put=to.remaining();
                 ByteBuffer slice=from.slice();
                 slice.limit(put);
                 to.put(slice);
                 from.position(from.position()+put);
             }
         }
         else
             put=0;
 
         return put;
     }
 
     /* ------------------------------------------------------------ */
     /**
      * Put data from one buffer into another, avoiding over/under flows
      * @param from Buffer to take bytes from in flush mode
      * @param to Buffer to put bytes to in flush mode. The buffer is flipToFill before the put and flipToFlush after.
      * @return number of bytes moved
      */
     public static int flipPutFlip(ByteBuffer from, ByteBuffer to)
     {
         int pos= flipToFill(to);
         try
         {
             return put(from,to);
         }
         finally
         {
             flipToFlush(to,pos);
         }
     }
 
     /* ------------------------------------------------------------ */
     /**
      */
     public static void append(ByteBuffer to, byte[] b,int off,int len)
     {
         int pos= flipToFill(to);
         try
         {
             to.put(b,off,len);
         }
         finally
         {
             flipToFlush(to,pos);
         }
     }
 
     /* ------------------------------------------------------------ */
     /**
      */
     public static void append(ByteBuffer to, byte b)
     {
         int limit=to.limit();
         to.limit(limit+1);
         to.put(limit,b);
     }
 
     /* ------------------------------------------------------------ */
     public static void readFrom(File file, ByteBuffer buffer) throws IOException
     {
         RandomAccessFile raf = new RandomAccessFile(file,"r");
         FileChannel channel = raf.getChannel();
         long needed=raf.length();
 
         while (needed>0 && buffer.hasRemaining())
             needed=needed-channel.read(buffer);
     }
 
     /* ------------------------------------------------------------ */
     public static void readFrom(InputStream is, int needed, ByteBuffer buffer) throws IOException
     {
         ByteBuffer tmp = allocate(8192);
 
         while (needed>0 && buffer.hasRemaining())
         {
             int l = is.read(tmp.array(),0,8192);
             if (l<0)
                 break;
             tmp.position(0);
             tmp.limit(l);
             buffer.put(tmp);
         }
     }
 
     /* ------------------------------------------------------------ */
     public static void writeTo(ByteBuffer buffer, OutputStream out) throws IOException
     {
         if (buffer.hasArray())
             out.write(buffer.array(),buffer.arrayOffset()+buffer.position(),buffer.remaining());
         else
         {
             // TODO this is horribly inefficient
             for (int i=buffer.position();i<buffer.limit();i++)
                 out.write(buffer.get(i));
         }
     }
 
     /* ------------------------------------------------------------ */
     /** Convert the buffer to an ISO-8859-1 String
      * @param buffer The buffer to convert in flush mode. The buffer is unchanged
      * @return The buffer as a string.
      */
     public static String toString(ByteBuffer buffer)
     {
         return toString(buffer,StringUtil.__ISO_8859_1_CHARSET);
     }
 
     /* ------------------------------------------------------------ */
     /** Convert the buffer to an UTF-8 String
      * @param buffer The buffer to convert in flush mode. The buffer is unchanged
      * @return The buffer as a string.
      */
     public static String toUTF8String(ByteBuffer buffer)
     {
         return toString(buffer,StringUtil.__UTF8_CHARSET);
     }
 
     /* ------------------------------------------------------------ */
     /** Convert the buffer to an ISO-8859-1 String
      * @param buffer The buffer to convert in flush mode. The buffer is unchanged
      * @param charset The {@link Charset} to use to convert the bytes
      * @return The buffer as a string.
      */
     public static String toString(ByteBuffer buffer, Charset charset)
     {
         if (buffer == null)
             return null;
         byte[] array = buffer.hasArray()?buffer.array():null;
         if (array == null)
         {
             byte[] to = new byte[buffer.remaining()];
             buffer.slice().get(to);
             return new String(to,0,to.length,charset);
         }
         return new String(array,buffer.arrayOffset()+buffer.position(),buffer.remaining(),charset);
     }
 
     /* ------------------------------------------------------------ */
     /** Convert a partial buffer to an ISO-8859-1 String
      * @param buffer The buffer to convert in flush mode. The buffer is unchanged
      * @param charset The {@link Charset} to use to convert the bytes
      * @return The buffer as a string.
      */
     public static String toString(ByteBuffer buffer, int position, int length, Charset charset)
     {
         if (buffer == null)
             return null;
         byte[] array = buffer.hasArray()?buffer.array():null;
         if (array == null)
         {
             ByteBuffer ro=buffer.asReadOnlyBuffer();
             ro.position(position);
             ro.limit(position+length);
             byte[] to = new byte[length];
             ro.get(to);
             return new String(to,0,to.length,charset);
         }
         return new String(array,buffer.arrayOffset()+position,length,charset);
     }
 
     /* ------------------------------------------------------------ */
     /**
      * Convert buffer to an integer. Parses up to the first non-numeric character. If no number is found an IllegalArgumentException is thrown
      *
      * @param buffer
      *            A buffer containing an integer in flush mode. The position is not changed.
      * @return an int
      */
     public static int toInt(ByteBuffer buffer)
     {
         int val = 0;
         boolean started = false;
         boolean minus = false;
 
         for (int i = buffer.position(); i < buffer.limit(); i++)
         {
             byte b = buffer.get(i);
             if (b <= SPACE)
             {
                 if (started)
                     break;
             }
             else if (b >= '0' && b <= '9')
             {
                 val = val * 10 + (b - '0');
                 started = true;
             }
             else if (b == MINUS && !started)
             {
                 minus = true;
             }
             else
                 break;
         }
 
         if (started)
             return minus?(-val):val;
         throw new NumberFormatException(toString(buffer));
     }
 
     /**
      * Convert buffer to an long. Parses up to the first non-numeric character. If no number is found an IllegalArgumentException is thrown
      *
      * @param buffer
      *            A buffer containing an integer in flush mode. The position is not changed.
      * @return an int
      */
     public static long toLong(ByteBuffer buffer)
     {
         long val = 0;
         boolean started = false;
         boolean minus = false;
 
         for (int i = buffer.position(); i < buffer.limit(); i++)
         {
             byte b = buffer.get(i);
             if (b <= SPACE)
             {
                 if (started)
                     break;
             }
             else if (b >= '0' && b <= '9')
             {
                 val = val * 10L + (b - '0');
                 started = true;
             }
             else if (b == MINUS && !started)
             {
                 minus = true;
             }
             else
                 break;
         }
 
         if (started)
             return minus?(-val):val;
         throw new NumberFormatException(toString(buffer));
     }
 
     public static void putHexInt(ByteBuffer buffer, int n)
     {
         if (n < 0)
         {
             buffer.put((byte)'-');
 
             if (n == Integer.MIN_VALUE)
             {
                 buffer.put((byte)(0x7f & '8'));
                 buffer.put((byte)(0x7f & '0'));
                 buffer.put((byte)(0x7f & '0'));
                 buffer.put((byte)(0x7f & '0'));
                 buffer.put((byte)(0x7f & '0'));
                 buffer.put((byte)(0x7f & '0'));
                 buffer.put((byte)(0x7f & '0'));
                 buffer.put((byte)(0x7f & '0'));
 
                 return;
             }
             n = -n;
         }
 
         if (n < 0x10)
         {
             buffer.put(DIGIT[n]);
         }
         else
         {
             boolean started = false;
             // This assumes constant time int arithmatic
             for (int i = 0; i < hexDivisors.length; i++)
             {
                 if (n < hexDivisors[i])
                 {
                     if (started)
                         buffer.put((byte)'0');
                     continue;
                 }
 
                 started = true;
                 int d = n / hexDivisors[i];
                 buffer.put(DIGIT[d]);
                 n = n - d * hexDivisors[i];
             }
         }
     }
 
     /* ------------------------------------------------------------ */
     public static void putDecInt(ByteBuffer buffer, int n)
     {
         if (n < 0)
         {
             buffer.put((byte)'-');
 
             if (n == Integer.MIN_VALUE)
             {
                 buffer.put((byte)'2');
                 n = 147483648;
             }
             else
                 n = -n;
         }
 
         if (n < 10)
         {
             buffer.put(DIGIT[n]);
         }
         else
         {
             boolean started = false;
             // This assumes constant time int arithmatic
             for (int i = 0; i < decDivisors.length; i++)
             {
                 if (n < decDivisors[i])
                 {
                     if (started)
                         buffer.put((byte)'0');
                     continue;
                 }
 
                 started = true;
                 int d = n / decDivisors[i];
                 buffer.put(DIGIT[d]);
                 n = n - d * decDivisors[i];
             }
         }
     }
 
     public static void putDecLong(ByteBuffer buffer, long n)
     {
         if (n < 0)
         {
             buffer.put((byte)'-');
 
             if (n == Long.MIN_VALUE)
             {
                 buffer.put((byte)'9');
                 n = 223372036854775808L;
             }
             else
                 n = -n;
         }
 
         if (n < 10)
         {
             buffer.put(DIGIT[(int)n]);
         }
         else
         {
             boolean started = false;
             // This assumes constant time int arithmatic
             for (int i = 0; i < decDivisorsL.length; i++)
             {
                 if (n < decDivisorsL[i])
                 {
                     if (started)
                         buffer.put((byte)'0');
                     continue;
                 }
 
                 started = true;
                 long d = n / decDivisorsL[i];
                 buffer.put(DIGIT[(int)d]);
                 n = n - d * decDivisorsL[i];
             }
         }
     }
 
     public static ByteBuffer toBuffer(int value)
     {
         ByteBuffer buf = ByteBuffer.allocate(32);
         putDecInt(buf,value);
         return buf;
     }
 
     public static ByteBuffer toBuffer(long value)
     {
         ByteBuffer buf = ByteBuffer.allocate(32);
         putDecLong(buf,value);
         return buf;
     }
 
     public static ByteBuffer toBuffer(String s)
     {
         return ByteBuffer.wrap(s.getBytes(StringUtil.__ISO_8859_1_CHARSET));
     }
     
     public static ByteBuffer toDirectBuffer(String s)
     {
         byte[] bytes=s.getBytes(StringUtil.__ISO_8859_1_CHARSET);
         ByteBuffer buf = ByteBuffer.allocateDirect(bytes.length);
         buf.put(bytes);
         buf.flip();
         return buf;
     }
 
     public static ByteBuffer toBuffer(String s, Charset charset)
     {
         return ByteBuffer.wrap(s.getBytes(charset));
     }
     
     public static ByteBuffer toDirectBuffer(String s, Charset charset)
     {
         byte[] bytes=s.getBytes(charset);
         ByteBuffer buf = ByteBuffer.allocateDirect(bytes.length);
         buf.put(bytes);
         buf.flip();
         return buf;
     }
 
     /**
      * Create a new ByteBuffer using provided byte array.
      *
      * @param array
      *            the byte array to back buffer with.
      * @return ByteBuffer with provided byte array, in flush mode
      */
     public static ByteBuffer toBuffer(byte array[])
     {
         return ByteBuffer.wrap(array);
     }
 
     /**
      * Create a new ByteBuffer using the provided byte array.
      *
      * @param array
      *            the byte array to use.
      * @param offset
      *            the offset within the byte array to use from
      * @param length
      *            the length in bytes of the array to use
      * @return ByteBuffer with provided byte array, in flush mode
      */
     public static ByteBuffer toBuffer(byte array[], int offset, int length)
     {
         return ByteBuffer.wrap(array,offset,length);
     }
 
     public static ByteBuffer toBuffer(File file) throws IOException
     {
         RandomAccessFile raf = new RandomAccessFile(file,"r");
         MappedByteBuffer buffer=raf.getChannel().map(MapMode.READ_ONLY,0,raf.length());
         return buffer;
     }
 
     public static String toSummaryString(ByteBuffer buffer)
     {
         if (buffer==null)
             return "null";
         StringBuilder buf = new StringBuilder();
         buf.append("[p=");
         buf.append(buffer.position());
         buf.append(",l=");
         buf.append(buffer.limit());
         buf.append(",c=");
         buf.append(buffer.capacity());
         buf.append(",r=");
         buf.append(buffer.remaining());
         buf.append("]");
         return buf.toString();
     }
 
     public static String toDetailString(ByteBuffer[] buffer)
     {
         StringBuilder builder = new StringBuilder();
         builder.append('[');
         for (int i=0;i<buffer.length;i++)
         {
             if (i>0) builder.append(',');
             builder.append(toDetailString(buffer[i]));
         }
         builder.append(']');
         return builder.toString();
     }
 
     public static String toDetailString(ByteBuffer buffer)
     {
         if (buffer==null)
             return "null";
 
         StringBuilder buf = new StringBuilder();
         buf.append(buffer.getClass().getSimpleName());
         buf.append("@");
         if (buffer.hasArray())
             buf.append(Integer.toHexString(((Object)buffer.array()).hashCode()));
         else
             buf.append(Integer.toHexString(buf.hashCode()));
         buf.append("[p=");
         buf.append(buffer.position());
         buf.append(",l=");
         buf.append(buffer.limit());
         buf.append(",c=");
         buf.append(buffer.capacity());
         buf.append(",r=");
         buf.append(buffer.remaining());
         buf.append("]={");
 
         for (int i=0;i<buffer.position();i++)
         {
             char c=(char)buffer.get(i);
             if (c>=' ' && c<=127)
                 buf.append(c);
             else if (c=='\r'||c=='\n')
                 buf.append('|');
             else
                 buf.append('\ufffd');
             if (i==16&&buffer.position()>32)
             {
                 buf.append("...");
                 i=buffer.position()-16;
             }
         }
         buf.append("<<<");
         for (int i=buffer.position();i<buffer.limit();i++)
         {
             char c=(char)buffer.get(i);
             if (c>=' ' && c<=127)
                 buf.append(c);
             else if (c=='\r'||c=='\n')
                 buf.append('|');
             else
                 buf.append('\ufffd');
             if (i==buffer.position()+16&&buffer.limit()>buffer.position()+32)
             {
                 buf.append("...");
                 i=buffer.limit()-16;
             }
         }
         buf.append(">>>");
         int limit=buffer.limit();
         buffer.limit(buffer.capacity());
         for (int i=limit;i<buffer.capacity();i++)
         {
             char c=(char)buffer.get(i);
             if (c>=' ' && c<=127)
                 buf.append(c);
             else if (c=='\r'||c=='\n')
                 buf.append('|');
             else
                 buf.append('\ufffd');
             if (i==limit+16&&buffer.capacity()>limit+32)
             {
                 buf.append("...");
                 i=buffer.capacity()-16;
             }
         }
         buffer.limit(limit);
         buf.append("}");
 
         return buf.toString();
     }
 
 
     private final static int[] decDivisors =
     { 1000000000, 100000000, 10000000, 1000000, 100000, 10000, 1000, 100, 10, 1 };
 
     private final static int[] hexDivisors =
     { 0x10000000, 0x1000000, 0x100000, 0x10000, 0x1000, 0x100, 0x10, 0x1 };
 
     private final static long[] decDivisorsL =
     { 1000000000000000000L, 100000000000000000L, 10000000000000000L, 1000000000000000L, 100000000000000L, 10000000000000L, 1000000000000L, 100000000000L,
             10000000000L, 1000000000L, 100000000L, 10000000L, 1000000L, 100000L, 10000L, 1000L, 100L, 10L, 1L };
 
     public static void putCRLF(ByteBuffer buffer)
     {
         buffer.put((byte)13);
         buffer.put((byte)10);
     }
 
     public static boolean isPrefix(ByteBuffer prefix, ByteBuffer buffer)
     {
         if (prefix.remaining() > buffer.remaining())
             return false;
         int bi = buffer.position();
         for (int i = prefix.position(); i < prefix.limit(); i++)
             if (prefix.get(i) != buffer.get(bi++))
                 return false;
         return true;
     }
 
 
 
 }