NPOI/Code/Npoi.Core/Util/LittleEndianByteArrayOutputStream.cs

/* ====================================================================
   Licensed to the Apache Software Foundation (ASF) under one or more
   contributor license agreements.  See the NOTICE file distributed with
   this work for additional information regarding copyright ownership.
   The ASF licenses this file to You under the Apache License, Version 2.0
   (the "License"); you may not use this file except in compliance with
   the License.  You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
==================================================================== */

namespace Npoi.Core.Util
{
    using System;
    using System.Globalization;

    /// <summary>
    /// Adapts a plain byte array to <see cref="T:Npoi.Core.Util.ILittleEndianOutput"/>
    /// </summary>
    /// <remarks>@author Josh Micich</remarks>
    public class LittleEndianByteArrayOutputStream : ILittleEndianOutput, IDelayableLittleEndianOutput
    {
        private byte[] _buf;
        private int _endIndex;
        private int _writeIndex;

        public LittleEndianByteArrayOutputStream(byte[] buf, int startOffset, int maxWriteLen)
        {
            if (startOffset < 0 || startOffset > buf.Length)
            {
                throw new ArgumentException("Specified startOffset (" + startOffset
                        + ") is out of allowable range (0.." + buf.Length + ")");
            }
            _buf = buf;
            _writeIndex = startOffset;
            _endIndex = startOffset + maxWriteLen;
            if (_endIndex < startOffset || _endIndex > buf.Length)
            {
                throw new ArgumentException("calculated end index (" + _endIndex
                        + ") is out of allowable range (" + _writeIndex + ".." + buf.Length + ")");
            }
        }
        public LittleEndianByteArrayOutputStream(byte[] buf, int startOffset) :
            this(buf, startOffset, buf.Length - startOffset)
        {

        }

        private void CheckPosition(int i)
        {
            if (i > _endIndex - _writeIndex)
            {
                throw new RuntimeException(string.Format(CultureInfo.InvariantCulture, "Buffer overrun i={0};endIndex={1};writeIndex={2}", i, _endIndex, _writeIndex));
            }
        }

        public void WriteByte(int v)
        {
            CheckPosition(1);
            _buf[_writeIndex++] = (byte)v;
        }

        public void WriteDouble(double v)
        {
            WriteLong(BitConverter.DoubleToInt64Bits(v));
        }

        public void WriteInt(int v)
        {
            CheckPosition(4);
            int i = _writeIndex;
            _buf[i++] = (byte)((v >> 0) & 0xFF);
            _buf[i++] = (byte)((v >> 8) & 0xFF);
            _buf[i++] = (byte)((v >> 16) & 0xFF);
            _buf[i++] = (byte)((v >> 24) & 0xFF);
            _writeIndex = i;
        }

        public void WriteLong(long v)
        {
            WriteInt((int)(v >> 0));
            WriteInt((int)(v >> 32));
        }

        public void WriteShort(int v)
        {
            CheckPosition(2);
            int i = _writeIndex;
            _buf[i++] = (byte)((v >> 0) & 0xFF);
            _buf[i++] = (byte)((v >> 8) & 0xFF);
            _writeIndex = i;
        }
        public void Write(byte[] b)
        {
            int len = b.Length;
            CheckPosition(len);
            System.Array.Copy(b, 0, _buf, _writeIndex, len);
            _writeIndex += len;
        }
        public void Write(byte[] b, int offset, int len)
        {
            CheckPosition(len);
            System.Array.Copy(b, offset, _buf, _writeIndex, len);
            _writeIndex += len;
        }
        public int WriteIndex
        {
            get
            {
                return _writeIndex;
            }
        }
        public ILittleEndianOutput CreateDelayedOutput(int size)
        {
            CheckPosition(size);
            ILittleEndianOutput result = new LittleEndianByteArrayOutputStream(_buf, _writeIndex, size);
            _writeIndex += size;
            return result;
        }
    }
}