Initial Commit

iTechSharp/srcbc/util/encoders/BufferedDecoder.cs

@@ -0,0 +1,117 @@
+using System;
+
+namespace Org.BouncyCastle.Utilities.Encoders
+{
+    /// <summary>
+    ///  A buffering class to allow translation from one format to another to
+    ///     be done in discrete chunks.
+    /// </summary>
+    public class BufferedDecoder
+    {
+        internal byte[]        buffer;
+        internal int           bufOff;
+
+        internal ITranslator   translator;
+
+        /// <summary>
+        /// Create a buffered Decoder.
+        /// </summary>
+        /// <param name="translator">The translater to use.</param>
+        /// <param name="bufferSize">The size of the buffer.</param>
+        public BufferedDecoder(
+            ITranslator translator,
+            int         bufferSize)
+        {
+            this.translator = translator;
+
+            if ((bufferSize % translator.GetEncodedBlockSize()) != 0)
+            {
+                throw new ArgumentException("buffer size not multiple of input block size");
+            }
+
+            buffer = new byte[bufferSize];
+//            bufOff = 0;
+        }
+
+        /// <summary>
+        /// Process one byte of data.
+        /// </summary>
+        /// <param name="input">Data in.</param>
+        /// <param name="output">Byte array for the output.</param>
+        /// <param name="outOff">The offset in the output byte array to start writing from.</param>
+        /// <returns>The amount of output bytes.</returns>
+        public int ProcessByte(
+            byte        input,
+            byte[]      output,
+            int         outOff)
+        {
+            int         resultLen = 0;
+
+            buffer[bufOff++] = input;
+
+            if (bufOff == buffer.Length)
+            {
+                resultLen = translator.Decode(buffer, 0, buffer.Length, output, outOff);
+                bufOff = 0;
+            }
+
+            return resultLen;
+        }
+
+
+        /// <summary>
+        /// Process data from a byte array.
+        /// </summary>
+        /// <param name="input">The input data.</param>
+        /// <param name="inOff">Start position within input data array.</param>
+        /// <param name="len">Amount of data to process from input data array.</param>
+        /// <param name="outBytes">Array to store output.</param>
+        /// <param name="outOff">Position in output array to start writing from.</param>
+        /// <returns>The amount of output bytes.</returns>
+        public int ProcessBytes(
+            byte[]      input,
+            int         inOff,
+            int         len,
+            byte[]      outBytes,
+            int         outOff)
+        {
+            if (len < 0)
+            {
+            throw new ArgumentException("Can't have a negative input length!");
+            }
+
+            int resultLen = 0;
+            int gapLen = buffer.Length - bufOff;
+
+            if (len > gapLen)
+            {
+                Array.Copy(input, inOff, buffer, bufOff, gapLen);
+
+                resultLen += translator.Decode(buffer, 0, buffer.Length, outBytes, outOff);
+
+                bufOff = 0;
+
+                len -= gapLen;
+                inOff += gapLen;
+                outOff += resultLen;
+
+                int chunkSize = len - (len % buffer.Length);
+
+                resultLen += translator.Decode(input, inOff, chunkSize, outBytes, outOff);
+
+                len -= chunkSize;
+                inOff += chunkSize;
+            }
+
+            if (len != 0)
+            {
+                Array.Copy(input, inOff, buffer, bufOff, len);
+
+                bufOff += len;
+            }
+
+            return resultLen;
+        }
+    }
+
+}