Tristan Matthews | 0a329cc | 2013-07-17 13:20:14 -0400 | [diff] [blame] | 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 |