diff -r 01e4e9ae323a -r 8b697d30c49f sources/huffman/bitwriter.h --- /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.
+ * 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.
+ * 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.
+ * 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 +