libremetaverse/CSJ2K/j2k/io/BufferedRandomAccessFile.cs

/*
* CVS Identifier:
*
* $Id: BufferedRandomAccessFile.java,v 1.21 2001/04/15 14:34:29 grosbois Exp $
*
* Interface:           RandomAccessIO.java
*
* Description:         Abstract class for buffered random access I/O.
*
*
*
* COPYRIGHT:
* 
* This software module was originally developed by Raphaël Grosbois and
* Diego Santa Cruz (Swiss Federal Institute of Technology-EPFL); Joel
* Askelöf (Ericsson Radio Systems AB); and Bertrand Berthelot, David
* Bouchard, Félix Henry, Gerard Mozelle and Patrice Onno (Canon Research
* Centre France S.A) in the course of development of the JPEG2000
* standard as specified by ISO/IEC 15444 (JPEG 2000 Standard). This
* software module is an implementation of a part of the JPEG 2000
* Standard. Swiss Federal Institute of Technology-EPFL, Ericsson Radio
* Systems AB and Canon Research Centre France S.A (collectively JJ2000
* Partners) agree not to assert against ISO/IEC and users of the JPEG
* 2000 Standard (Users) any of their rights under the copyright, not
* including other intellectual property rights, for this software module
* with respect to the usage by ISO/IEC and Users of this software module
* or modifications thereof for use in hardware or software products
* claiming conformance to the JPEG 2000 Standard. Those intending to use
* this software module in hardware or software products are advised that
* their use may infringe existing patents. The original developers of
* this software module, JJ2000 Partners and ISO/IEC assume no liability
* for use of this software module or modifications thereof. No license
* or right to this software module is granted for non JPEG 2000 Standard
* conforming products. JJ2000 Partners have full right to use this
* software module for his/her own purpose, assign or donate this
* software module to any third party and to inhibit third parties from
* using this software module for non JPEG 2000 Standard conforming
* products. This copyright notice must be included in all copies or
* derivative works of this software module.
* 
* Copyright (c) 1999/2000 JJ2000 Partners.
* */
namespace CSJ2K.j2k.io
{
	using System;
	using System.IO;

	using CSJ2K.Util;

	/// <summary> This class defines a Buffered Random Access File.  It implements the
	/// <tt>BinaryDataInput</tt> and <tt>BinaryDataOutput</tt> interfaces so that
	/// binary data input/output can be performed. This class is abstract since no
	/// assumption is done about the byte ordering type (little Endian, big
	/// Endian). So subclasses will have to implement methods like
	/// <tt>readShort()</tt>, <tt>writeShort()</tt>, <tt>readFloat()</tt>, ...
	/// 
	/// <P><tt>BufferedRandomAccessFile</tt> (BRAF for short) is a
	/// <tt>RandomAccessFile</tt> containing an extra buffer. When the BRAF is
	/// accessed, it checks if the requested part of the file is in the buffer or
	/// not. If that is the case, the read/write is done on the buffer. If not, the
	/// file is uppdated to reflect the current status of the buffer and the file
	/// is then accessed for a new buffer containing the requested byte/bit.
	/// 
	/// </summary>
	/// <seealso cref="RandomAccessIO">
	/// </seealso>
	/// <seealso cref="BinaryDataOutput">
	/// </seealso>
	/// <seealso cref="BinaryDataInput">
	/// </seealso>
	/// <seealso cref="BEBufferedRandomAccessFile">
	/// 
	/// </seealso>
	public abstract class BufferedRandomAccessFile : RandomAccessIO, EndianType
	{
		/// <summary> Returns the current offset in the file
		/// 
		/// </summary>
		virtual public int Pos
		{
			get
			{
				return (offset + position);
			}
			
		}
		/// <summary> Returns the endianess (i.e., byte ordering) of the implementing
		/// class. Note that an implementing class may implement only one
		/// type of endianness or both, which would be decided at creation
		/// time.
		/// 
		/// </summary>
		/// <returns> Either <tt>EndianType.BIG_ENDIAN</tt> or
		/// <tt>EndianType.LITTLE_ENDIAN</tt>
		/// 
		/// </returns>
		/// <seealso cref="EndianType">
		/// 
		/// </seealso>
		virtual public int ByteOrdering
		{
			get
			{
				return byte_Ordering;
			}
			
		}
		
		/// <summary>The name of the current file </summary>
		private System.String fileName;
		
		/// <summary> Whether the opened file is read only or not (defined by the constructor
		/// arguments)
		/// 
		/// </summary>
		private bool isReadOnly = true;
		
		/// <summary> The RandomAccessFile associated with the buffer
		/// 
		/// </summary>
		//UPGRADE_TODO: Class 'java.io.RandomAccessFile' was converted to 'System.IO.FileStream' which has a different behavior. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1073_javaioRandomAccessFile'"
		private System.IO.Stream theFile;
		
		/// <summary> Buffer of bytes containing the part of the file that is currently being
		/// accessed
		/// 
		/// </summary>
		protected internal byte[] byteBuffer;
		
		/// <summary> Boolean keeping track of whether the byte buffer has been changed since
		/// it was read.
		/// 
		/// </summary>
		protected internal bool byteBufferChanged;
		
		/// <summary> The current offset of the buffer (which will differ from the offset of
		/// the file) 
		/// 
		/// </summary>
		protected internal int offset;
		
		/// <summary> The current position in the byte-buffer
		/// 
		/// </summary>
		protected internal int position;
		
		/// <summary> The maximum number of bytes that can be read from the buffer
		/// 
		/// </summary>
		protected internal int maxByte;
		
		/// <summary> Whether the end of the file is in the current buffer or not
		/// 
		/// </summary>
		protected internal bool isEOFInBuffer;
		
		/* The endianess of the class */
		protected internal int byte_Ordering;

		/// <summary> Constructor. Always needs a size for the buffer.
		/// 
		/// </summary>
		/// <param name="stream">The stream associated with the buffer
		/// 
		/// </param>
		/// <param name="isReadOnly">Indicates whether file is read-only or not.</param>
		/// <param name="bufferSize">The number of bytes to buffer
		/// 
		/// </param>
		/// <exception cref="IOException">If an I/O error ocurred.
		/// 
		/// </exception>
		protected internal BufferedRandomAccessFile(Stream stream, bool isReadOnly, int bufferSize)
		{
			fileName = String.Empty;
			theFile = stream;
			this.isReadOnly = isReadOnly;
			byteBuffer = new byte[bufferSize];
			readNewBuffer(0);
		}

		/// <summary> Constructor. Uses the default value for the byte-buffer 
		/// size (512 bytes).
		/// 
		/// </summary>
		/// <param name="stream">The stream associated with the buffer
		/// 
		/// </param>
		/// <param name="isReadOnly">Indicates whether file is read-only or not.</param>
		/// <exception cref="IOException">If an I/O error ocurred.
		/// 
		/// </exception>
		protected internal BufferedRandomAccessFile(Stream stream, bool isReadOnly)
			: this(stream, isReadOnly, 512)
		{
		}

		/// <summary> Constructor. Always needs a size for the buffer.
		/// 
		/// </summary>
		/// <param name="file">The file associated with the buffer
		/// 
		/// </param>
		/// <param name="mode">"r" for read, "rw" or "rw+" for read and write mode ("rw+"
		/// opens the file for update whereas "rw" removes it
		/// before. So the 2 modes are different only if the file
		/// already exists).
		/// 
		/// </param>
		/// <param name="bufferSize">The number of bytes to buffer
		/// 
		/// </param>
		/// <exception cref="IOException">If an I/O error ocurred.
		/// 
		/// </exception>
		protected internal BufferedRandomAccessFile(IFileInfo file, System.String mode, int bufferSize)
		{
			
			fileName = file.Name;
			if (mode.Equals("rw") || mode.Equals("rw+"))
			{
				// mode read / write
				isReadOnly = false;
				if (mode.Equals("rw"))
				{
					if (file.Exists && !file.Delete())
					{
						throw new System.IO.IOException("Could not delete existing file");
					}
				}
				mode = "rw";
			}
			theFile = SupportClass.RandomAccessFileSupport.CreateRandomAccessFile(file, mode);
			byteBuffer = new byte[bufferSize];
			readNewBuffer(0);
		}
		
		/// <summary> Constructor. Uses the default value for the byte-buffer 
		/// size (512 bytes).
		/// 
		/// </summary>
		/// <param name="file">The file associated with the buffer
		/// 
		/// </param>
		/// <param name="mode">"r" for read, "rw" or "rw+" for read and write mode
		/// ("rw+" opens the file for update whereas "rw" removes 
		/// it before. So the 2 modes are different only if the 
		/// file already exists).
		/// 
		/// </param>
		/// <exception cref="IOException">If an I/O error ocurred.
		/// 
		/// </exception>
		protected internal BufferedRandomAccessFile(IFileInfo file, System.String mode):this(file, mode, 512)
		{
		}
		
		/// <summary> Constructor. Always needs a size for the buffer.
		/// 
		/// </summary>
		/// <param name="name">The name of the file associated with the buffer
		/// 
		/// </param>
		/// <param name="mode">"r" for read, "rw" or "rw+" for read and write mode
		/// ("rw+" opens the file for update whereas "rw" removes 
		/// it before. So the 2 modes are different only if the 
		/// file already exists).
		/// 
		/// </param>
		/// <param name="bufferSize">The number of bytes to buffer
		/// 
		/// </param>
		/// <exception cref="IOException">If an I/O error ocurred.
		/// 
		/// </exception>
		protected internal BufferedRandomAccessFile(System.String name, System.String mode, int bufferSize):this(FileInfoFactory.New(name), mode, bufferSize)
		{
		}
		
		/// <summary> Constructor. Uses the default value for the byte-buffer 
		/// size (512 bytes).
		/// 
		/// </summary>
		/// <param name="name">The name of the file associated with the buffer
		/// 
		/// </param>
		/// <param name="mode">"r" for read, "rw" or "rw+" for read and write mode
		/// ("rw+" opens the file for update whereas "rw" removes 
		/// it before. So the 2 modes are different only if the 
		/// file already exists).
		/// 
		/// </param>
		/// <exception cref="IOException">If an I/O error ocurred.
		/// 
		/// </exception>
		protected internal BufferedRandomAccessFile(System.String name, System.String mode):this(name, mode, 512)
		{
		}
		
		/// <summary> Reads a new buffer from the file. If there has been any
		/// changes made since the buffer was read, the buffer is 
		/// first written to the file.
		/// 
		/// </summary>
		/// <param name="off">The offset where to move to.
		/// 
		/// </param>
		/// <exception cref="IOException">If an I/O error ocurred.
		/// 
		/// </exception>
		protected internal void  readNewBuffer(int off)
		{
			
			/* If the buffer have changed. We need to write it to 
			* the file before reading a new buffer.
			*/
			if (byteBufferChanged)
			{
				flush();
			}
			// Don't allow to seek beyond end of file if reading only
			if (isReadOnly && off >= theFile.Length)
			{
				throw new System.IO.EndOfStreamException();
			}
			// Set new offset
			offset = off;
			
			theFile.Seek(offset, System.IO.SeekOrigin.Begin);
			
			maxByte = theFile.Read(byteBuffer, 0, byteBuffer.Length);
			position = 0;
			
			if (maxByte < byteBuffer.Length)
			{
				// Not enough data in input file.
				isEOFInBuffer = true;
				if (maxByte == - 1)
				{
					maxByte++;
				}
			}
			else
			{
				isEOFInBuffer = false;
			}
		}
		
		/// <summary> Closes the buffered random access file
		/// 
		/// </summary>
		/// <exception cref="IOException">If an I/O error ocurred.
		/// 
		/// </exception>
		public virtual void  close()
		{
			/* If the buffer has been changed, it need to be saved before
			* closing
			*/
			flush();
			byteBuffer = null; // Release the byte-buffer reference
		}
		
		/// <summary> Returns the current length of the stream, in bytes, taking into
		/// account any buffering.
		/// 
		/// </summary>
		/// <returns> The length of the stream, in bytes.
		/// 
		/// </returns>
		/// <exception cref="IOException">If an I/O error ocurred.
		/// 
		/// </exception>
		public virtual int length()
		{
			int len;
			
			len = (int) theFile.Length;
			
			// If the position in the buffer is not past the end of the file,
			// the length of theFile is the length of the stream
			if ((offset + maxByte) <= len)
			{
				return (len);
			}
			else
			{
				// If not, the file is extended due to the buffering
				return (offset + maxByte);
			}
		}
		
		/// <summary> Moves the current position to the given offset at which the
		/// next read or write occurs. The offset is measured from the 
		/// beginning of the stream.
		/// 
		/// </summary>
		/// <param name="off">The offset where to move to.
		/// 
		/// </param>
		/// <exception cref="EOFException">If in read-only and seeking beyond EOF.
		/// 
		/// </exception>
		/// <exception cref="IOException">If an I/O error ocurred.
		/// 
		/// </exception>
		public virtual void  seek(int off)
		{
			/* If the new offset is within the buffer, only the pos value needs
			* to be modified. Else, the buffer must be moved. */
			if ((off >= offset) && (off < (offset + byteBuffer.Length)))
			{
				if (isReadOnly && isEOFInBuffer && off > offset + maxByte)
				{
					// We are seeking beyond EOF in read-only mode!
					throw new System.IO.EndOfStreamException();
				}
				position = off - offset;
			}
			else
			{
				readNewBuffer(off);
			}
		}
		
		/// <summary> Reads an unsigned byte of data from the stream. Prior to reading, the
		/// stream is realigned at the byte level.
		/// 
		/// </summary>
		/// <returns> The byte read.
		/// 
		/// </returns>
		/// <exception cref="IOException">If an I/O error ocurred.
		/// 
		/// </exception>
		/// <exception cref="java.io.EOFException">If the end of file was reached
		/// 
		/// </exception>
		public byte readByte() { return read(); }
		public byte readUnsignedByte() { return read(); }
		public byte read()
		{
			if (position < maxByte)
			{
				// The byte can be read from the buffer
				// In Java, the bytes are always signed.
				return (byteBuffer[position++]);
			}
			else if (isEOFInBuffer)
			{
				// EOF is reached
				position = maxByte + 1; // Set position to EOF
				throw new System.IO.EndOfStreamException();
			}
			else
			{
				// End of the buffer is reached
				readNewBuffer(offset + position);
				return read();
			}
		}
		
		/// <summary> Reads up to len bytes of data from this file into an array of
		/// bytes. This method reads repeatedly from the stream until all the bytes
		/// are read. This method blocks until all the bytes are read, the end of
		/// the stream is detected, or an exception is thrown.
		/// 
		/// </summary>
		/// <param name="b">The buffer into which the data is to be read. It must be long
		/// enough.
		/// 
		/// </param>
		/// <param name="off">The index in 'b' where to place the first byte read.
		/// 
		/// </param>
		/// <param name="len">The number of bytes to read.
		/// 
		/// </param>
		/// <exception cref="EOFException">If the end-of file was reached before
		/// getting all the necessary data.
		/// 
		/// </exception>
		/// <exception cref="IOException">If an I/O error ocurred.
		/// 
		/// </exception>
		public void  readFully(byte[] b, int off, int len)
		{
			int clen; // current length to read
			while (len > 0)
			{
				// There still is some data to read
				if (position < maxByte)
				{
					// We can read some data from buffer
					clen = maxByte - position;
					if (clen > len)
						clen = len;
					Array.Copy(byteBuffer, position, b, off, clen);
					position += clen;
					off += clen;
					len -= clen;
				}
				else if (isEOFInBuffer)
				{
					position = maxByte + 1; // Set position to EOF
					throw new System.IO.EndOfStreamException();
				}
				else
				{
					// Buffer empty => get more data
					readNewBuffer(offset + position);
				}
			}
		}
		
		/// <summary> Writes a byte to the stream. Prior to writing, the stream is
		/// realigned at the byte level.
		/// 
		/// </summary>
		/// <param name="b">The byte to write. The lower 8 bits of <tt>b</tt> are
		/// written.
		/// 
		/// </param>
		/// <exception cref="IOException">If an I/O error ocurred.
		/// 
		/// </exception>
		public void  write(int b)
		{
			// As long as pos is less than the length of the buffer we can write
			// to the buffer. If the position is after the buffer a new buffer is
			// needed
			if (position < byteBuffer.Length)
			{
				if (isReadOnly)
					throw new System.IO.IOException("File is read only");
				byteBuffer[position] = (byte) b;
				if (position >= maxByte)
				{
					maxByte = position + 1;
				}
				position++;
				byteBufferChanged = true;
			}
			else
			{
				readNewBuffer(offset + position);
				write(b);
			}
		}
		
		/// <summary> Writes a byte to the stream. Prior to writing, the stream is
		/// realigned at the byte level.
		/// 
		/// </summary>
		/// <param name="b">The byte to write.
		/// 
		/// </param>
		/// <exception cref="IOException">If an I/O error ocurred.
		/// 
		/// </exception>
		public void  write(byte b)
		{
			// As long as pos is less than the length of the buffer we can write
			// to the buffer. If the position is after the buffer a new buffer is
			// needed
			if (position < byteBuffer.Length)
			{
				if (isReadOnly)
					throw new System.IO.IOException("File is read only");
				byteBuffer[position] = b;
				if (position >= maxByte)
				{
					maxByte = position + 1;
				}
				position++;
				byteBufferChanged = true;
			}
			else
			{
				readNewBuffer(offset + position);
				write(b);
			}
		}
		
		/// <summary> Writes aan array of bytes to the stream. Prior to writing, the stream is
		/// realigned at the byte level.
		/// 
		/// </summary>
		/// <param name="b">The array of bytes to write. 
		/// 
		/// </param>
		/// <param name="offset">The first byte in b to write 
		/// 
		/// </param>
		/// <param name="length">The number of bytes from b to write 
		/// 
		/// </param>
		/// <exception cref="IOException">If an I/O error ocurred.
		/// 
		/// </exception>
		public void  write(byte[] b, int offset, int length)
		{
			int i, stop;
			stop = offset + length;
			if (stop > b.Length)
				throw new System. IndexOutOfRangeException("Index of bound " + b.Length);
			for (i = offset; i < stop; i++)
			{
				write(b[i]);
			}
		}
		
		/// <summary> Writes the byte value of <tt>v</tt> (i.e., 8 least
		/// significant bits) to the output. Prior to writing, the output
		/// should be realigned at the byte level.
		/// 
		/// <P>Signed or unsigned data can be written. To write a signed
		/// value just pass the <tt>byte</tt> value as an argument. To
		/// write unsigned data pass the <tt>int</tt> value as an argument
		/// (it will be automatically casted, and only the 8 least
		/// significant bits will be written).
		/// 
		/// </summary>
		/// <param name="v">The value to write to the output
		/// 
		/// </param>
		/// <exception cref="IOException">If an I/O error ocurred.
		/// 
		/// </exception>
		public void  writeByte(int v)
		{
			write(v);
		}
		
		/// <summary> Any data that has been buffered must be written (including
		/// buffering at the bit level), and the stream should be realigned
		/// at the byte level.
		/// 
		/// </summary>
		/// <exception cref="IOException">If an I/O error ocurred.
		/// 
		/// </exception>
		public void  flush()
		{
			if (byteBufferChanged)
			{
				theFile.Seek(offset, System.IO.SeekOrigin.Begin);
				theFile.Write(byteBuffer, 0, maxByte);
				byteBufferChanged = false;
			}
		}
		/*
		/// <summary> Reads a signed byte (i.e., 8 bit) from the input. Prior to 
		/// reading, the input should be realigned at the byte level.
		/// 
		/// </summary>
		/// <returns> The next byte-aligned signed byte (8 bit) from the
		/// input.
		/// 
		/// </returns>
		/// <exception cref="java.io.EOFException">If the end-of file was reached before
		/// getting all the necessary data.
		/// 
		/// </exception>
		/// <exception cref="java.io.IOException">If an I/O error ocurred.
		/// 
		/// </exception>
		public byte readByte()
		{
			if (pos < maxByte)
			{
				// The byte can be read from the buffer
				// In Java, the bytes are always signed.
				return byteBuffer[pos++];
			}
			else if (isEOFInBuffer)
			{
				// EOF is reached
				pos = maxByte + 1; // Set position to EOF
				throw new System.IO.EndOfStreamException();
			}
			else
			{
				// End of the buffer is reached
				readNewBuffer(offset + pos);
				return readByte();
			}
		}
		
		/// <summary> Reads an unsigned byte (i.e., 8 bit) from the input. It is
		/// returned as an <tt>int</tt> since Java does not have an
		/// unsigned byte type. Prior to reading, the input should be
		/// realigned at the byte level.
		/// 
		/// </summary>
		/// <returns> The next byte-aligned unsigned byte (8 bit) from the
		/// input, as an <tt>int</tt>.
		/// 
		/// </returns>
		/// <exception cref="java.io.EOFException">If the end-of file was reached before
		/// getting all the necessary data.
		/// 
		/// </exception>
		/// <exception cref="java.io.IOException">If an I/O error ocurred.
		/// 
		/// </exception>
		public int readUnsignedByte()
		{
			return read();
		}
		*/
		/// <summary> Skips <tt>n</tt> bytes from the input. Prior to skipping, the
		/// input should be realigned at the byte level.
		/// 
		/// </summary>
		/// <param name="n">The number of bytes to skip
		/// 
		/// </param>
		/// <exception cref="java.io.EOFException">If the end-of file was reached before
		/// all the bytes could be skipped.
		/// 
		/// </exception>
		/// <exception cref="IOException">If an I/O error ocurred.
		/// 
		/// </exception>
		public virtual int skipBytes(int n)
		{
			if (n < 0)
				throw new System.ArgumentException("Can not skip negative number " + "of bytes");
			if (n <= (maxByte - position))
			{
				position += n;
				return n;
			}
			else
			{
				seek(offset + position + n);
				return n;
			}
		}
		
		/// <summary> Returns a string of information about the file
		/// 
		/// </summary>
		public override System.String ToString()
		{
			return "BufferedRandomAccessFile: " + fileName + " (" + ((isReadOnly)?"read only":"read/write") + ")";
		}
		public abstract int readUnsignedShort();
		public abstract void  writeLong(long param1);
		public abstract void  writeShort(int param1);
		public abstract float readFloat();
		public abstract short readShort();
		public abstract double readDouble();
		public abstract int readInt();
		public abstract long readLong();
		public abstract long readUnsignedInt();
		public abstract void  writeDouble(double param1);
		public abstract void  writeFloat(float param1);
		public abstract void  writeInt(int param1);
	}
}