Mercurial > zfc9000 / file diff

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/sources/huffman/bitwriter.h	Thu Dec 11 07:18:11 2014 +0200
@@ -0,0 +1,109 @@
+/*
+ * skulltag::BitWriter class - Enables writing arbitrary bit lengths of data.
+ *
+ * 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_WRITER_VERSION
+#define _BIT_WRITER_VERSION 1
+
+/** Prevents naming convention problems via encapsulation. */
+namespace skulltag { // scope limitation
+
+/** BitWriter - Allows writing of varying amounts of bits to a char buffer. <br>
+ * Very usefull for outputting variable bit length encodings such as Huffman. */
+
+	class BitWriter {
+		int bufferBits;					/**< intermediary buffer of bits. */
+		int bitsLeft;					/**< number of bits left in the buffer. */
+		unsigned char * currentByte;	/**< position in memory the next char will be stored. */
+		int bytesAvailable;				/**< amount of available space left in the output buffer in bytes. Excludes the contents of bufferBits. */
+		int bitsAvailable;				/**< amount of available space left in the output buffer in bits. Includes the contents of bufferBits. */
+		int maximumBytes;				/**< total amount of bytes that can be written to the output 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. */
+public:
+
+		/** Creates a new BitWriter. */
+		BitWriter();
+
+		/** Creates a new BitWriter.
+		 * @param output	Destination that bits will be written to.
+		 * @param max		Maximum number of chars to output. */
+		BitWriter( unsigned char * const output, int const &max );
+
+		/** Appends a char worth of bits to the buffer.
+		 * @param bits 		the bits to append.
+		 * @return true if successful, false if an error occurs. */
+		bool put( unsigned char const &bits );
+
+		/** Appends a short worth of bits to the buffer.
+		 * @param bits 		the bits to append.
+		 * @return true if successful, false otherwise.
+		 * @return true if successful, false if an error occurs. */
+		bool put( short const &bits );
+
+		/** Appends an int worth of bits to the buffer.
+		 * @param bits 		the bits to append.
+		 * @return true if successful, false if an error occurs. */
+		bool put( int const &bits );
+
+		/** Appends a specified number of bits from an int to the buffer.
+		 * @param bits 		the bits to append. <br>
+		 *		The bits should be stored in the least significant portion of the int.
+		 * @param count		the number of bits to append.
+		 * @return true if successful, false if an error occurs. */
+		bool put( int const &bits, int count );
+
+		/** Appends multiple chars from a buffer to this BitWriter.
+		 * @param inputBuffer 		pointer to char data
+		 * @param count				number of chars to read
+		 * @return true if successful, false if an error occurs. */
+		bool put( unsigned char const * const inputBuffer, int count );
+
+		/** Sets the output buffer that bytes will be written to.
+		 * @param output	Destination that bits will be written to.
+		 * @param max		Maximum number of chars to output.
+		 * @return true if successful, false if an error occurs. */
+		bool outputBuffer( unsigned char * const output, int const &max );
+
+		/** Writes any full chars of data stored in this BitWriter to the output char buffer.
+		 * @return true if successful, false if an error occurs. */
+		bool flush();
+
+		/** Flushes this BitWriter then outputs any partial chars by padding them with zeros. <br>
+		 * After calling finish() all other calls to update the BitWriter will fail until a buffer is set via outputBuffer().
+		 * @param bytesWritten 	out: the number of bytes written to the output buffer.
+		 * @param paddingBits	out: the number of padding bits used in the final byte of output.
+		 * @return true if successful, false if an error occurs. */
+		bool finish( int &bytesWritten, int &paddingBits );
+
+	private:
+
+		/** Initializes this BitWriter. */
+		void init();
+
+	};
+
+}
+#endif
+