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175 lines
6.5 KiB
C
175 lines
6.5 KiB
C
/* Copyright (C) 2002 Jean-Marc Valin */
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/**
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@file speex_bits.h
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@brief Handles bit packing/unpacking
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*/
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/*
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions
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are met:
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- Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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- Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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- Neither the name of the Xiph.org Foundation nor the names of its
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contributors may be used to endorse or promote products derived from
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this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR
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CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef BITS_H
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#define BITS_H
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/** @defgroup SpeexBits SpeexBits: Bit-stream manipulations
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* This is the structure that holds the bit-stream when encoding or decoding
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* with Speex. It allows some manipulations as well.
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* @{
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*/
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#ifdef __cplusplus
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extern "C" {
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#endif
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/** Bit-packing data structure representing (part of) a bit-stream. */
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typedef struct SpeexBits {
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char *chars; /**< "raw" data */
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int nbBits; /**< Total number of bits stored in the stream*/
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int charPtr; /**< Position of the byte "cursor" */
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int bitPtr; /**< Position of the bit "cursor" within the current char */
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int owner; /**< Does the struct "own" the "raw" buffer (member "chars") */
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int overflow;/**< Set to one if we try to read past the valid data */
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int buf_size;/**< Allocated size for buffer */
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int reserved1; /**< Reserved for future use */
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void *reserved2; /**< Reserved for future use */
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} SpeexBits;
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/** Initializes and allocates resources for a SpeexBits struct */
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void speex_bits_init(SpeexBits *bits);
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/** Initializes SpeexBits struct using a pre-allocated buffer*/
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void speex_bits_init_buffer(SpeexBits *bits, void *buff, int buf_size);
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/** Sets the bits in a SpeexBits struct to use data from an existing buffer (for decoding without copying data) */
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void speex_bits_set_bit_buffer(SpeexBits *bits, void *buff, int buf_size);
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/** 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.*/
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void speex_bits_destroy(SpeexBits *bits);
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/** Resets bits to initial value (just after initialization, erasing content)*/
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void speex_bits_reset(SpeexBits *bits);
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/** Rewind the bit-stream to the beginning (ready for read) without erasing the content */
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void speex_bits_rewind(SpeexBits *bits);
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/** Initializes the bit-stream from the data in an area of memory */
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void speex_bits_read_from(SpeexBits *bits, char *bytes, int len);
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/** Append bytes to the bit-stream
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*
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* @param bits Bit-stream to operate on
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* @param bytes pointer to the bytes what will be appended
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* @param len Number of bytes of append
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*/
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void speex_bits_read_whole_bytes(SpeexBits *bits, char *bytes, int len);
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/** Write the content of a bit-stream to an area of memory
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*
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* @param bits Bit-stream to operate on
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* @param bytes Memory location where to write the bits
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* @param max_len Maximum number of bytes to write (i.e. size of the "bytes" buffer)
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* @return Number of bytes written to the "bytes" buffer
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*/
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int speex_bits_write(SpeexBits *bits, char *bytes, int max_len);
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/** Like speex_bits_write, but writes only the complete bytes in the stream. Also removes the written bytes from the stream */
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int speex_bits_write_whole_bytes(SpeexBits *bits, char *bytes, int max_len);
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/** Append bits to the bit-stream
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* @param bits Bit-stream to operate on
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* @param data Value to append as integer
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* @param nbBits number of bits to consider in "data"
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*/
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void speex_bits_pack(SpeexBits *bits, int data, int nbBits);
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/** Interpret the next bits in the bit-stream as a signed integer
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*
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* @param bits Bit-stream to operate on
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* @param nbBits Number of bits to interpret
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* @return A signed integer represented by the bits read
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*/
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int speex_bits_unpack_signed(SpeexBits *bits, int nbBits);
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/** Interpret the next bits in the bit-stream as an unsigned integer
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*
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* @param bits Bit-stream to operate on
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* @param nbBits Number of bits to interpret
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* @return An unsigned integer represented by the bits read
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*/
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unsigned int speex_bits_unpack_unsigned(SpeexBits *bits, int nbBits);
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/** Returns the number of bytes in the bit-stream, including the last one even if it is not "full"
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*
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* @param bits Bit-stream to operate on
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* @return Number of bytes in the stream
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*/
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int speex_bits_nbytes(SpeexBits *bits);
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/** Same as speex_bits_unpack_unsigned, but without modifying the cursor position
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*
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* @param bits Bit-stream to operate on
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* @param nbBits Number of bits to look for
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* @return Value of the bits peeked, interpreted as unsigned
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*/
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unsigned int speex_bits_peek_unsigned(SpeexBits *bits, int nbBits);
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/** Get the value of the next bit in the stream, without modifying the
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* "cursor" position
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*
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* @param bits Bit-stream to operate on
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* @return Value of the bit peeked (one bit only)
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*/
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int speex_bits_peek(SpeexBits *bits);
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/** Advances the position of the "bit cursor" in the stream
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*
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* @param bits Bit-stream to operate on
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* @param n Number of bits to advance
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*/
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void speex_bits_advance(SpeexBits *bits, int n);
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/** Returns the number of bits remaining to be read in a stream
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*
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* @param bits Bit-stream to operate on
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* @return Number of bits that can still be read from the stream
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*/
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int speex_bits_remaining(SpeexBits *bits);
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/** Insert a terminator so that the data can be sent as a packet while auto-detecting
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* the number of frames in each packet
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*
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* @param bits Bit-stream to operate on
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*/
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void speex_bits_insert_terminator(SpeexBits *bits);
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#ifdef __cplusplus
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}
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#endif
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/* @} */
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#endif
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