Mercurial > zfc9000 / file diff

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/huffman/bitreader.h	Fri May 15 20:13:36 2015 +0300
@@ -0,0 +1,85 @@
+/**
+ * skulltag::BitReader class - Allows reading arbitrary bit lengths of data.
+ * Version 1 - Revsion 0
+ *
+ * Copyright 2009 Timothy Landers
+ * email: code.vortexcortex@gmail.com
+ *
+ * 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.
+ */
+
+#ifndef _BIT_READER_VERSION
+#define _BIT_READER_VERSION 1
+
+/** Prevents naming convention problems via encapsulation. */
+namespace skulltag { // scope limitation
+
+/** BitReader - Allows reading of varying amounts of bits from a char buffer. <br>
+ * Very usefull for inputting variable bit length encodings such as Huffman. */
+
+	class BitReader {
+		int bufferBits;					/**< intermediary buffer of bits. */
+		int bitsUsed;					/**< number of bits used in the buffer. */
+		unsigned char const * currentByte;	/**< position in memory the next char will be read. */
+		int bytesAvailable;				/**< amount of available space left in the input buffer in bytes. Excludes the contents of bufferBits. */
+		int bitsAvailable;				/**< amount of available space left in the input buffer in bits. Includes the contents of bufferBits. */
+		int maximumBytes;				/**< total amount of bytes that can be read from the input buffer. */
+		static int mask[];				/**< maps a number of bits to a bit mask containing as many bits. */
+		static int intSize;				/**< number of chars in an int. */
+		static int intBitSize;			/**< number of bits in an ing. */
+public:
+
+		/** Creates a new BitReader. */
+		BitReader();
+
+		/** Creates a new BitReader.
+		 * @param input		Source of data that bits will be read from.
+		 * @param max		Maximum number of chars to read. */
+		BitReader( unsigned char const * input, int const &max );
+
+		/** Sets the input buffer that bytes will be read from.
+		 * @param input		Source of data that bits will be read from.
+		 * @param max		Maximum number of chars to input.
+		 * @return true if successful, false if an error occurs. */
+		bool inputBuffer( unsigned char const * input, int const &max );
+		
+		/** Fetches a specified number of bits and stores them in an int.
+		 * @param bits 		destination of the retrieved bits. <br>
+		 *		The bits will be stored in the least significant portion of the int.
+		 * @param count		the number of bits to fetch.
+		 * @return the number of bits read -- may not be equal to the amount requested. */
+		int get( int &bits, int const &count );
+
+		/** @return Amount of bits that can be read from this BitReader. */
+		int availableBits();
+
+	private:
+
+		/** Fills the internal bit buffer.
+		 * @return true if successful, false if an error occurs. */
+		bool fill();
+
+		/** Initializes this BitReader. */
+		void init();
+
+	};
+
+}
+#endif
+