source: branches/RemoveBackwardsCompatibility/HeuristicLab.ExtLibs/HeuristicLab.Cecil/0.9.5/Mono.Cecil-0.9.5/Mono.Cecil/Mono.Cecil.PE/ByteBuffer.cs

//
// ByteBuffer.cs
//
// Author:
//   Jb Evain (jbevain@gmail.com)
//
// Copyright (c) 2008 - 2011 Jb Evain
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//

using System;

namespace Mono.Cecil.PE {

  class ByteBuffer {

    internal byte [] buffer;
    internal int length;
    internal int position;

    public ByteBuffer ()
    {
      this.buffer = Empty<byte>.Array;
    }

    public ByteBuffer (int length)
    {
      this.buffer = new byte [length];
    }

    public ByteBuffer (byte [] buffer)
    {
      this.buffer = buffer ?? Empty<byte>.Array;
      this.length = this.buffer.Length;
    }

    public void Reset (byte [] buffer)
    {
      this.buffer = buffer ?? Empty<byte>.Array;
      this.length = this.buffer.Length;
    }

    public void Advance (int length)
    {
      position += length;
    }

    public byte ReadByte ()
    {
      return buffer [position++];
    }

    public sbyte ReadSByte ()
    {
      return (sbyte) ReadByte ();
    }

    public byte [] ReadBytes (int length)
    {
      var bytes = new byte [length];
      Buffer.BlockCopy (buffer, position, bytes, 0, length);
      position += length;
      return bytes;
    }

    public ushort ReadUInt16 ()
    {
      ushort value = (ushort) (buffer [position]
        | (buffer [position + 1] << 8));
      position += 2;
      return value;
    }

    public short ReadInt16 ()
    {
      return (short) ReadUInt16 ();
    }

    public uint ReadUInt32 ()
    {
      uint value = (uint) (buffer [position]
        | (buffer [position + 1] << 8)
        | (buffer [position + 2] << 16)
        | (buffer [position + 3] << 24));
      position += 4;
      return value;
    }

    public int ReadInt32 ()
    {
      return (int) ReadUInt32 ();
    }

    public ulong ReadUInt64 ()
    {
      uint low = ReadUInt32 ();
      uint high = ReadUInt32 ();

      return (((ulong) high) << 32) | low;
    }

    public long ReadInt64 ()
    {
      return (long) ReadUInt64 ();
    }

    public uint ReadCompressedUInt32 ()
    {
      byte first = ReadByte ();
      if ((first & 0x80) == 0)
        return first;

      if ((first & 0x40) == 0)
        return ((uint) (first & ~0x80) << 8)
          | ReadByte ();

      return ((uint) (first & ~0xc0) << 24)
        | (uint) ReadByte () << 16
        | (uint) ReadByte () << 8
        | ReadByte ();
    }

    public int ReadCompressedInt32 ()
    {
      var value = (int) ReadCompressedUInt32 ();

      return (value & 1) != 0
        ? -(value >> 1)
        : value >> 1;
    }

    public float ReadSingle ()
    {
      if (!BitConverter.IsLittleEndian) {
        var bytes = ReadBytes (4);
        Array.Reverse (bytes);
        return BitConverter.ToSingle (bytes, 0);
      }

      float value = BitConverter.ToSingle (buffer, position);
      position += 4;
      return value;
    }

    public double ReadDouble ()
    {
      if (!BitConverter.IsLittleEndian) {
        var bytes = ReadBytes (8);
        Array.Reverse (bytes);
        return BitConverter.ToDouble (bytes, 0);
      }

      double value = BitConverter.ToDouble (buffer, position);
      position += 8;
      return value;
    }

#if !READ_ONLY

    public void WriteByte (byte value)
    {
      if (position == buffer.Length)
        Grow (1);

      buffer [position++] = value;

      if (position > length)
        length = position;
    }

    public void WriteSByte (sbyte value)
    {
      WriteByte ((byte) value);
    }

    public void WriteUInt16 (ushort value)
    {
      if (position + 2 > buffer.Length)
        Grow (2);

      buffer [position++] = (byte) value;
      buffer [position++] = (byte) (value >> 8);

      if (position > length)
        length = position;
    }

    public void WriteInt16 (short value)
    {
      WriteUInt16 ((ushort) value);
    }

    public void WriteUInt32 (uint value)
    {
      if (position + 4 > buffer.Length)
        Grow (4);

      buffer [position++] = (byte) value;
      buffer [position++] = (byte) (value >> 8);
      buffer [position++] = (byte) (value >> 16);
      buffer [position++] = (byte) (value >> 24);

      if (position > length)
        length = position;
    }

    public void WriteInt32 (int value)
    {
      WriteUInt32 ((uint) value);
    }

    public void WriteUInt64 (ulong value)
    {
      if (position + 8 > buffer.Length)
        Grow (8);

      buffer [position++] = (byte) value;
      buffer [position++] = (byte) (value >> 8);
      buffer [position++] = (byte) (value >> 16);
      buffer [position++] = (byte) (value >> 24);
      buffer [position++] = (byte) (value >> 32);
      buffer [position++] = (byte) (value >> 40);
      buffer [position++] = (byte) (value >> 48);
      buffer [position++] = (byte) (value >> 56);

      if (position > length)
        length = position;
    }

    public void WriteInt64 (long value)
    {
      WriteUInt64 ((ulong) value);
    }

    public void WriteCompressedUInt32 (uint value)
    {
      if (value < 0x80)
        WriteByte ((byte) value);
      else if (value < 0x4000) {
        WriteByte ((byte) (0x80 | (value >> 8)));
        WriteByte ((byte) (value & 0xff));
      } else {
        WriteByte ((byte) ((value >> 24) | 0xc0));
        WriteByte ((byte) ((value >> 16) & 0xff));
        WriteByte ((byte) ((value >> 8) & 0xff));
        WriteByte ((byte) (value & 0xff));
      }
    }

    public void WriteCompressedInt32 (int value)
    {
      WriteCompressedUInt32 ((uint) ((value < 0) ? ((-value) << 1) | 1 : value << 1));
    }

    public void WriteBytes (byte [] bytes)
    {
      var length = bytes.Length;
      if (position + length > buffer.Length)
        Grow (length);

      Buffer.BlockCopy (bytes, 0, buffer, position, length);
      position += length;

      if (position > this.length)
        this.length = position;
    }

    public void WriteBytes (int length)
    {
      if (position + length > buffer.Length)
        Grow (length);

      position += length;

      if (position > this.length)
        this.length = position;
    }

    public void WriteBytes (ByteBuffer buffer)
    {
      if (position + buffer.length > this.buffer.Length)
        Grow (buffer.length);

      Buffer.BlockCopy (buffer.buffer, 0, this.buffer, position, buffer.length);
      position += buffer.length;

      if (position > this.length)
        this.length = position;
    }

    public void WriteSingle (float value)
    {
      var bytes = BitConverter.GetBytes (value);

      if (!BitConverter.IsLittleEndian)
        Array.Reverse (bytes);

      WriteBytes (bytes);
    }

    public void WriteDouble (double value)
    {
      var bytes = BitConverter.GetBytes (value);

      if (!BitConverter.IsLittleEndian)
        Array.Reverse (bytes);

      WriteBytes (bytes);
    }

    void Grow (int desired)
    {
      var current = this.buffer;
      var current_length = current.Length;

      var buffer = new byte [System.Math.Max (current_length + desired, current_length * 2)];
      Buffer.BlockCopy (current, 0, buffer, 0, current_length);
      this.buffer = buffer;
    }

#endif

  }
}