root/trunk/Updater/ICSharpCode.SharpZipLib/Zip/Compression/PendingBuffer.cs @ 597

// PendingBuffer.cs
//
// Copyright (C) 2001 Mike Krueger
// Copyright (C) 2004 John Reilly
//
// This file was translated from java, it was part of the GNU Classpath
// Copyright (C) 2001 Free Software Foundation, Inc.
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
//
// Linking this library statically or dynamically with other modules is
// making a combined work based on this library.  Thus, the terms and
// conditions of the GNU General Public License cover the whole
// combination.
// 
// As a special exception, the copyright holders of this library give you
// permission to link this library with independent modules to produce an
// executable, regardless of the license terms of these independent
// modules, and to copy and distribute the resulting executable under
// terms of your choice, provided that you also meet, for each linked
// independent module, the terms and conditions of the license of that
// module.  An independent module is a module which is not derived from
// or based on this library.  If you modify this library, you may extend
// this exception to your version of the library, but you are not
// obligated to do so.  If you do not wish to do so, delete this
// exception statement from your version.

using System;

namespace ICSharpCode.SharpZipLib.Zip.Compression 
{
        
        /// <summary>
        /// This class is general purpose class for writing data to a buffer.
        /// 
        /// It allows you to write bits as well as bytes
        /// Based on DeflaterPending.java
        /// 
        /// author of the original java version : Jochen Hoenicke
        /// </summary>
        public class PendingBuffer
        {
                #region Instance Fields
                /// <summary>
                /// Internal work buffer
                /// </summary>
                byte[] buffer_;
                
                int    start;
                int    end;
                
                uint   bits;
                int    bitCount;
                #endregion

                #region Constructors
                /// <summary>
                /// construct instance using default buffer size of 4096
                /// </summary>
                public PendingBuffer() : this( 4096 )
                {
                }
                
                /// <summary>
                /// construct instance using specified buffer size
                /// </summary>
                /// <param name="bufferSize">
                /// size to use for internal buffer
                /// </param>
                public PendingBuffer(int bufferSize)
                {
                        buffer_ = new byte[bufferSize];
                }

                #endregion

                /// <summary>
                /// Clear internal state/buffers
                /// </summary>
                public void Reset() 
                {
                        start = end = bitCount = 0;
                }

                /// <summary>
                /// Write a byte to buffer
                /// </summary>
                /// <param name="value">
                /// The value to write
                /// </param>
                public void WriteByte(int value)
                {
#if DebugDeflation
                        if (DeflaterConstants.DEBUGGING && (start != 0) )
                        {
                                throw new SharpZipBaseException("Debug check: start != 0");
                        }
#endif
                        buffer_[end++] = unchecked((byte) value);
                }

                /// <summary>
                /// Write a short value to buffer LSB first
                /// </summary>
                /// <param name="value">
                /// The value to write.
                /// </param>
                public void WriteShort(int value)
                {
#if DebugDeflation
                        if (DeflaterConstants.DEBUGGING && (start != 0) )
                        {
                                throw new SharpZipBaseException("Debug check: start != 0");
                        }
#endif
                        buffer_[end++] = unchecked((byte) value);
                        buffer_[end++] = unchecked((byte) (value >> 8));
                }

                /// <summary>
                /// write an integer LSB first
                /// </summary>
                /// <param name="value">The value to write.</param>
                public void WriteInt(int value)
                {
#if DebugDeflation
                        if (DeflaterConstants.DEBUGGING && (start != 0) )
                        {
                                throw new SharpZipBaseException("Debug check: start != 0");
                        }
#endif
                        buffer_[end++] = unchecked((byte) value);
                        buffer_[end++] = unchecked((byte) (value >> 8));
                        buffer_[end++] = unchecked((byte) (value >> 16));
                        buffer_[end++] = unchecked((byte) (value >> 24));
                }
                
                /// <summary>
                /// Write a block of data to buffer
                /// </summary>
                /// <param name="block">data to write</param>
                /// <param name="offset">offset of first byte to write</param>
                /// <param name="length">number of bytes to write</param>
                public void WriteBlock(byte[] block, int offset, int length)
                {
#if DebugDeflation
                        if (DeflaterConstants.DEBUGGING && (start != 0) ) 
                        {
                                throw new SharpZipBaseException("Debug check: start != 0");
                        }
#endif
                        System.Array.Copy(block, offset, buffer_, end, length);
                        end += length;
                }

                /// <summary>
                /// The number of bits written to the buffer
                /// </summary>
                public int BitCount {
                        get {
                                return bitCount;
                        }
                }
                
                /// <summary>
                /// Align internal buffer on a byte boundary
                /// </summary>
                public void AlignToByte() 
                {
#if DebugDeflation
                        if (DeflaterConstants.DEBUGGING && (start != 0) ) 
                        {
                                throw new SharpZipBaseException("Debug check: start != 0");
                        }
#endif
                        if (bitCount > 0) 
                        {
                                buffer_[end++] = unchecked((byte) bits);
                                if (bitCount > 8) {
                                        buffer_[end++] = unchecked((byte) (bits >> 8));
                                }
                        }
                        bits = 0;
                        bitCount = 0;
                }

                /// <summary>
                /// Write bits to internal buffer
                /// </summary>
                /// <param name="b">source of bits</param>
                /// <param name="count">number of bits to write</param>
                public void WriteBits(int b, int count)
                {
#if DebugDeflation
                        if (DeflaterConstants.DEBUGGING && (start != 0) ) 
                        {
                                throw new SharpZipBaseException("Debug check: start != 0");
                        }

                        //                      if (DeflaterConstants.DEBUGGING) {
                        //                              //Console.WriteLine("writeBits("+b+","+count+")");
                        //                      }
#endif
                        bits |= (uint)(b << bitCount);
                        bitCount += count;
                        if (bitCount >= 16) {
                                buffer_[end++] = unchecked((byte) bits);
                                buffer_[end++] = unchecked((byte) (bits >> 8));
                                bits >>= 16;
                                bitCount -= 16;
                        }
                }

                /// <summary>
                /// Write a short value to internal buffer most significant byte first
                /// </summary>
                /// <param name="s">value to write</param>
                public void WriteShortMSB(int s) 
                {
#if DebugDeflation
                        if (DeflaterConstants.DEBUGGING && (start != 0) ) 
                        {
                                throw new SharpZipBaseException("Debug check: start != 0");
                        }
#endif
                        buffer_[end++] = unchecked((byte) (s >> 8));
                        buffer_[end++] = unchecked((byte) s);
                }
                
                /// <summary>
                /// Indicates if buffer has been flushed
                /// </summary>
                public bool IsFlushed {
                        get {
                                return end == 0;
                        }
                }
                
                /// <summary>
                /// Flushes the pending buffer into the given output array.  If the
                /// output array is to small, only a partial flush is done.
                /// </summary>
                /// <param name="output">The output array.</param>
                /// <param name="offset">The offset into output array.</param>
                /// <param name="length">The maximum number of bytes to store.</param>
                /// <returns>The number of bytes flushed.</returns>
                public int Flush(byte[] output, int offset, int length) 
                {
                        if (bitCount >= 8) {
                                buffer_[end++] = unchecked((byte) bits);
                                bits >>= 8;
                                bitCount -= 8;
                        }

                        if (length > end - start) {
                                length = end - start;
                                System.Array.Copy(buffer_, start, output, offset, length);
                                start = 0;
                                end = 0;
                        } else {
                                System.Array.Copy(buffer_, start, output, offset, length);
                                start += length;
                        }
                        return length;
                }

                /// <summary>
                /// Convert internal buffer to byte array.
                /// Buffer is empty on completion
                /// </summary>
                /// <returns>
                /// The internal buffer contents converted to a byte array.
                /// </returns>
                public byte[] ToByteArray()
                {
                        byte[] result = new byte[end - start];
                        System.Array.Copy(buffer_, start, result, 0, result.Length);
                        start = 0;
                        end = 0;
                        return result;
                }
        }
}