comparison: sources/huffman/bitreader.h
sources/huffman/bitreader.h
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- 6de6d9a64ebd
- parent 75
- 5f8a03274d75
- child 77
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| 75:5f8a03274d75 | 76:6de6d9a64ebd |
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| 1 /** | |
| 2 * skulltag::BitReader class - Allows reading arbitrary bit lengths of data. | |
| 3 * Version 1 - Revsion 0 | |
| 4 * | |
| 5 * Copyright 2009 Timothy Landers | |
| 6 * email: code.vortexcortex@gmail.com | |
| 7 * | |
| 8 * Permission is hereby granted, free of charge, to any person obtaining a copy | |
| 9 * of this software and associated documentation files (the "Software"), to deal | |
| 10 * in the Software without restriction, including without limitation the rights | |
| 11 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell | |
| 12 * copies of the Software, and to permit persons to whom the Software is | |
| 13 * furnished to do so, subject to the following conditions: | |
| 14 * | |
| 15 * The above copyright notice and this permission notice shall be included in | |
| 16 * all copies or substantial portions of the Software. | |
| 17 * | |
| 18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR | |
| 19 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, | |
| 20 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE | |
| 21 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER | |
| 22 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, | |
| 23 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN | |
| 24 * THE SOFTWARE. | |
| 25 */ | |
| 26 | |
| 27 #ifndef _BIT_READER_VERSION | |
| 28 #define _BIT_READER_VERSION 1 | |
| 29 | |
| 30 /** Prevents naming convention problems via encapsulation. */ | |
| 31 namespace skulltag { // scope limitation | |
| 32 | |
| 33 /** BitReader - Allows reading of varying amounts of bits from a char buffer. <br> | |
| 34 * Very usefull for inputting variable bit length encodings such as Huffman. */ | |
| 35 | |
| 36 class BitReader { | |
| 37 int bufferBits; /**< intermediary buffer of bits. */ | |
| 38 int bitsUsed; /**< number of bits used in the buffer. */ | |
| 39 unsigned char const * currentByte; /**< position in memory the next char will be read. */ | |
| 40 int bytesAvailable; /**< amount of available space left in the input buffer in bytes. Excludes the contents of bufferBits. */ | |
| 41 int bitsAvailable; /**< amount of available space left in the input buffer in bits. Includes the contents of bufferBits. */ | |
| 42 int maximumBytes; /**< total amount of bytes that can be read from the input buffer. */ | |
| 43 static int mask[]; /**< maps a number of bits to a bit mask containing as many bits. */ | |
| 44 static int intSize; /**< number of chars in an int. */ | |
| 45 static int intBitSize; /**< number of bits in an ing. */ | |
| 46 public: | |
| 47 | |
| 48 /** Creates a new BitReader. */ | |
| 49 BitReader(); | |
| 50 | |
| 51 /** Creates a new BitReader. | |
| 52 * @param input Source of data that bits will be read from. | |
| 53 * @param max Maximum number of chars to read. */ | |
| 54 BitReader( unsigned char const * input, int const &max ); | |
| 55 | |
| 56 /** Sets the input buffer that bytes will be read from. | |
| 57 * @param input Source of data that bits will be read from. | |
| 58 * @param max Maximum number of chars to input. | |
| 59 * @return true if successful, false if an error occurs. */ | |
| 60 bool inputBuffer( unsigned char const * input, int const &max ); | |
| 61 | |
| 62 /** Fetches a specified number of bits and stores them in an int. | |
| 63 * @param bits destination of the retrieved bits. <br> | |
| 64 * The bits will be stored in the least significant portion of the int. | |
| 65 * @param count the number of bits to fetch. | |
| 66 * @return the number of bits read -- may not be equal to the amount requested. */ | |
| 67 int get( int &bits, int const &count ); | |
| 68 | |
| 69 /** @return Amount of bits that can be read from this BitReader. */ | |
| 70 int availableBits(); | |
| 71 | |
| 72 private: | |
| 73 | |
| 74 /** Fills the internal bit buffer. | |
| 75 * @return true if successful, false if an error occurs. */ | |
| 76 bool fill(); | |
| 77 | |
| 78 /** Initializes this BitReader. */ | |
| 79 void init(); | |
| 80 | |
| 81 }; | |
| 82 | |
| 83 } | |
| 84 #endif | |
| 85 |
