1 /* Copyright (C) 2002 Jean-Marc Valin */ 2 /** 3 @file speex_bits.h 4 @brief Handles bit packing/unpacking 5 */ 6 /* 7 Redistribution and use in source and binary forms, with or without 8 modification, are permitted provided that the following conditions 9 are met: 10 11 - Redistributions of source code must retain the above copyright 12 notice, this list of conditions and the following disclaimer. 13 14 - Redistributions in binary form must reproduce the above copyright 15 notice, this list of conditions and the following disclaimer in the 16 documentation and/or other materials provided with the distribution. 17 18 - Neither the name of the Xiph.org Foundation nor the names of its 19 contributors may be used to endorse or promote products derived from 20 this software without specific prior written permission. 21 22 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 23 ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 24 LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 25 A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR 26 CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 27 EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 28 PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 29 PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF 30 LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING 31 NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS 32 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 33 34 */ 35 36 #ifndef BITS_H 37 #define BITS_H 38 /** @defgroup SpeexBits SpeexBits: Bit-stream manipulations 39 * This is the structure that holds the bit-stream when encoding or decoding 40 * with Speex. It allows some manipulations as well. 41 * @{ 42 */ 43 44 #ifdef __cplusplus 45 extern "C" { 46 #endif 47 48 /** Bit-packing data structure representing (part of) a bit-stream. */ 49 typedef struct SpeexBits { 50 char *chars; /**< "raw" data */ 51 int nbBits; /**< Total number of bits stored in the stream*/ 52 int charPtr; /**< Position of the byte "cursor" */ 53 int bitPtr; /**< Position of the bit "cursor" within the current char */ 54 int owner; /**< Does the struct "own" the "raw" buffer (member "chars") */ 55 int overflow;/**< Set to one if we try to read past the valid data */ 56 int buf_size;/**< Allocated size for buffer */ 57 int reserved1; /**< Reserved for future use */ 58 void *reserved2; /**< Reserved for future use */ 59 } SpeexBits; 60 61 /** Initializes and allocates resources for a SpeexBits struct */ 62 void speex_bits_init(SpeexBits *bits); 63 64 /** Initializes SpeexBits struct using a pre-allocated buffer*/ 65 void speex_bits_init_buffer(SpeexBits *bits, void *buff, int buf_size); 66 67 /** Sets the bits in a SpeexBits struct to use data from an existing buffer (for decoding without copying data) */ 68 void speex_bits_set_bit_buffer(SpeexBits *bits, void *buff, int buf_size); 69 70 /** Frees all resources associated to a SpeexBits struct. Right now this does nothing since no resources are allocated, but this could change in the future.*/ 71 void speex_bits_destroy(SpeexBits *bits); 72 73 /** Resets bits to initial value (just after initialization, erasing content)*/ 74 void speex_bits_reset(SpeexBits *bits); 75 76 /** Rewind the bit-stream to the beginning (ready for read) without erasing the content */ 77 void speex_bits_rewind(SpeexBits *bits); 78 79 /** Initializes the bit-stream from the data in an area of memory */ 80 void speex_bits_read_from(SpeexBits *bits, char *bytes, int len); 81 82 /** Append bytes to the bit-stream 83 * 84 * @param bits Bit-stream to operate on 85 * @param bytes pointer to the bytes what will be appended 86 * @param len Number of bytes of append 87 */ 88 void speex_bits_read_whole_bytes(SpeexBits *bits, char *bytes, int len); 89 90 /** Write the content of a bit-stream to an area of memory 91 * 92 * @param bits Bit-stream to operate on 93 * @param bytes Memory location where to write the bits 94 * @param max_len Maximum number of bytes to write (i.e. size of the "bytes" buffer) 95 * @return Number of bytes written to the "bytes" buffer 96 */ 97 int speex_bits_write(SpeexBits *bits, char *bytes, int max_len); 98 99 /** Like speex_bits_write, but writes only the complete bytes in the stream. Also removes the written bytes from the stream */ 100 int speex_bits_write_whole_bytes(SpeexBits *bits, char *bytes, int max_len); 101 102 /** Append bits to the bit-stream 103 * @param bits Bit-stream to operate on 104 * @param data Value to append as integer 105 * @param nbBits number of bits to consider in "data" 106 */ 107 void speex_bits_pack(SpeexBits *bits, int data, int nbBits); 108 109 /** Interpret the next bits in the bit-stream as a signed integer 110 * 111 * @param bits Bit-stream to operate on 112 * @param nbBits Number of bits to interpret 113 * @return A signed integer represented by the bits read 114 */ 115 int speex_bits_unpack_signed(SpeexBits *bits, int nbBits); 116 117 /** Interpret the next bits in the bit-stream as an unsigned integer 118 * 119 * @param bits Bit-stream to operate on 120 * @param nbBits Number of bits to interpret 121 * @return An unsigned integer represented by the bits read 122 */ 123 unsigned int speex_bits_unpack_unsigned(SpeexBits *bits, int nbBits); 124 125 /** Returns the number of bytes in the bit-stream, including the last one even if it is not "full" 126 * 127 * @param bits Bit-stream to operate on 128 * @return Number of bytes in the stream 129 */ 130 int speex_bits_nbytes(SpeexBits *bits); 131 132 /** Same as speex_bits_unpack_unsigned, but without modifying the cursor position 133 * 134 * @param bits Bit-stream to operate on 135 * @param nbBits Number of bits to look for 136 * @return Value of the bits peeked, interpreted as unsigned 137 */ 138 unsigned int speex_bits_peek_unsigned(SpeexBits *bits, int nbBits); 139 140 /** Get the value of the next bit in the stream, without modifying the 141 * "cursor" position 142 * 143 * @param bits Bit-stream to operate on 144 * @return Value of the bit peeked (one bit only) 145 */ 146 int speex_bits_peek(SpeexBits *bits); 147 148 /** Advances the position of the "bit cursor" in the stream 149 * 150 * @param bits Bit-stream to operate on 151 * @param n Number of bits to advance 152 */ 153 void speex_bits_advance(SpeexBits *bits, int n); 154 155 /** Returns the number of bits remaining to be read in a stream 156 * 157 * @param bits Bit-stream to operate on 158 * @return Number of bits that can still be read from the stream 159 */ 160 int speex_bits_remaining(SpeexBits *bits); 161 162 /** Insert a terminator so that the data can be sent as a packet while auto-detecting 163 * the number of frames in each packet 164 * 165 * @param bits Bit-stream to operate on 166 */ 167 void speex_bits_insert_terminator(SpeexBits *bits); 168 169 #ifdef __cplusplus 170 } 171 #endif 172 173 /* @} */ 174 #endif 175
