/WorldView/Utilities/BufferedBinaryReader.cs

using System;

using System.IO;



namespace MoreTerra.Utilities

{

	class BufferedBinaryReader

	{

		private Int32 bufferSize;

		private Int32 maxBufferSize;

		private Byte[] buffer;

		private Stream stream;

		private Int64 bufferPosition;

		private Int64 startPosition;

		private Int64 endPosition;

		private Int64 streamEnd;

		private Int32 oldMininum;

		

		public BufferedBinaryReader(Stream str, Int32 bSize, Int32 oldMin)

		{

			if (str == null)

				return;



			stream = str;



			streamEnd = stream.Length;

			oldMininum = oldMin;



			if (bSize < 0)

				return;



			maxBufferSize = bSize;



			buffer = new Byte[maxBufferSize];



			bufferPosition = stream.Position;

			startPosition = stream.Position;

			endPosition = startPosition + bufferSize;

		}



		public Boolean ReadBoolean()

		{

			Int64 readPos;





			readPos = bufferPosition - startPosition;



			if (readPos >= bufferSize)

			{

				FillBuffer();



				if (bufferSize <= 0)

					throw new EndOfStreamException();



				readPos = bufferPosition - startPosition;

			}



			bufferPosition++;

			if (buffer[readPos] > 1)

				return true;



			return false;

		}



		public Byte ReadByte()

		{

			Int64 readPos;



			readPos = bufferPosition - startPosition;



			if (readPos >= bufferSize)

			{

				FillBuffer();



				if (bufferSize <= 0)

					throw new EndOfStreamException();



				readPos = bufferPosition - startPosition;

			}



			bufferPosition++;

			return buffer[readPos];

		}



		public short ReadInt16()

		{

			Int16 ret16 = 0;



			Int64 readPos;



			readPos = bufferPosition - startPosition;



			if (readPos >= bufferSize - 1)

			{

				FillBuffer();



				if (bufferSize <= 0)

					throw new EndOfStreamException();



				readPos = bufferPosition - startPosition;

			}



			bufferPosition += 2;

			ret16 = buffer[readPos++];

			ret16 += (Int16) (buffer[readPos++] * 256);



			return ret16;

		}





		private void FillBuffer()

		{

			Int64 readOffset;

			Int32 readCount;

			Int32 readBytes;



			readOffset = stream.Position - oldMininum;



			if (readOffset < 0)

				readOffset = 0;



			readCount = maxBufferSize;

			if (readOffset + readCount > streamEnd)

				readCount = (Int32) (streamEnd - readOffset);



			stream.Seek(readOffset, SeekOrigin.Begin);

			readBytes = stream.Read(buffer, 0, readCount);



			startPosition = readOffset;

			endPosition = readOffset + readBytes;

			bufferSize = readBytes;

		}



		public void Seek(Int64 offset)

		{

			bufferPosition = offset;

		}



		public Int64 Position

		{

			get

			{

				return bufferPosition;

			}

		}



	}

}