/// <summary> /// Copies compressed contents from <paramref name="source"/> into the <paramref name="target"/> from the <paramref name="targetOffset"/> /// </summary> /// <param name="target">The <see cref="ByteBuffer"/> that will be written to.</param> /// <param name="source">The source <see cref="ByteBuffer"/> to read the data from.</param> /// <param name="targetOffset">The <paramref name="target"/> buffer's offset to start writing from.</param> /// <returns>The number of bytes written.</returns> public static int CompressedCopy(this ByteBuffer target, ByteBuffer source, int targetOffset) { byte[] compressed; using (var ms = new MemoryStream(source.ToArray())) { compressed = Compress(ms); } target.BlockCopy(compressed, 0, targetOffset, compressed.Length); return compressed.Length; }
/// <summary> /// Reads bytes from a specific offset. /// </summary> /// <param name="buffer">The buffer to read the bytes from.</param> /// <param name="offset">The offset in the buffer to start reading.</param> /// <param name="length">The number of bytes to read.</param> /// <returns>The value read from the buffer.</returns> public static byte[] ReadBytes(this byte[] buffer, int offset, int length) { byte[] bytes = new byte[length]; buffer.BlockCopy(offset, bytes, 0, length); return bytes; }
/// <summary> /// Decompress a byte array. /// </summary> /// <param name="source">The <see cref="Byte"/> array to decompress.</param> /// <param name="length">The number of bytes to read into the byte array for compression.</param> /// <param name="startIndex">An <see cref="Int32"/> representing the start index of the byte array.</param> /// <returns>A decompressed <see cref="Byte"/> array.</returns> public static byte[] Decompress(this byte[] source, int startIndex, int length) { const byte CompressionStrengthMask = (byte)(Bits.Bit00 | Bits.Bit01); // Unmask compression strength from first buffer byte CompressionStrength strength = (CompressionStrength)(source[startIndex] & CompressionStrengthMask); if (strength == CompressionStrength.NoCompression) { // No compression was applied to original buffer, return specified portion of the buffer return source.BlockCopy(startIndex + 1, length - 1); } else { // Create a new decompression deflater MemoryStream compressedData = new MemoryStream(source, startIndex + 1, length - 1); DeflateStream inflater = new DeflateStream(compressedData, CompressionMode.Decompress); int compressionDepth = (source[startIndex] & ~CompressionStrengthMask) >> 2; // Read uncompressed data byte[] destination = inflater.ReadStream(); // When user requests muli-pass compression, there may be multiple compression passes on a buffer, // so we cycle through the needed uncompressions to get back to the original data if (strength == CompressionStrength.MultiPass && compressionDepth > 0) return destination.Decompress(); else return destination; } }