/* * This file is part of FFmpeg. * * FFmpeg is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * FFmpeg is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with FFmpeg; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ /** * @file * @ingroup lavu_fifo * A generic FIFO API */ #ifndef AVUTIL_FIFO_H #define AVUTIL_FIFO_H #include <stddef.h> /** * @defgroup lavu_fifo AVFifo * @ingroup lavu_data * * @{ * A generic FIFO API */ AVFifo; /** * Callback for writing or reading from a FIFO, passed to (and invoked from) the * av_fifo_*_cb() functions. It may be invoked multiple times from a single * av_fifo_*_cb() call and may process less data than the maximum size indicated * by nb_elems. * * @param opaque the opaque pointer provided to the av_fifo_*_cb() function * @param buf the buffer for reading or writing the data, depending on which * av_fifo_*_cb function is called * @param nb_elems On entry contains the maximum number of elements that can be * read from / written into buf. On success, the callback should * update it to contain the number of elements actually written. * * @return 0 on success, a negative error code on failure (will be returned from * the invoking av_fifo_*_cb() function) */ AVFifoCB; /** * Automatically resize the FIFO on writes, so that the data fits. This * automatic resizing happens up to a limit that can be modified with * av_fifo_auto_grow_limit(). */ #define AV_FIFO_FLAG_AUTO_GROW … /** * Allocate and initialize an AVFifo with a given element size. * * @param elems initial number of elements that can be stored in the FIFO * @param elem_size Size in bytes of a single element. Further operations on * the returned FIFO will implicitly use this element size. * @param flags a combination of AV_FIFO_FLAG_* * * @return newly-allocated AVFifo on success, a negative error code on failure */ AVFifo *av_fifo_alloc2(size_t elems, size_t elem_size, unsigned int flags); /** * @return Element size for FIFO operations. This element size is set at * FIFO allocation and remains constant during its lifetime */ size_t av_fifo_elem_size(const AVFifo *f); /** * Set the maximum size (in elements) to which the FIFO can be resized * automatically. Has no effect unless AV_FIFO_FLAG_AUTO_GROW is used. */ void av_fifo_auto_grow_limit(AVFifo *f, size_t max_elems); /** * @return number of elements available for reading from the given FIFO. */ size_t av_fifo_can_read(const AVFifo *f); /** * @return Number of elements that can be written into the given FIFO without * growing it. * * In other words, this number of elements or less is guaranteed to fit * into the FIFO. More data may be written when the * AV_FIFO_FLAG_AUTO_GROW flag was specified at FIFO creation, but this * may involve memory allocation, which can fail. */ size_t av_fifo_can_write(const AVFifo *f); /** * Enlarge an AVFifo. * * On success, the FIFO will be large enough to hold exactly * inc + av_fifo_can_read() + av_fifo_can_write() * elements. In case of failure, the old FIFO is kept unchanged. * * @param f AVFifo to resize * @param inc number of elements to allocate for, in addition to the current * allocated size * @return a non-negative number on success, a negative error code on failure */ int av_fifo_grow2(AVFifo *f, size_t inc); /** * Write data into a FIFO. * * In case nb_elems > av_fifo_can_write(f) and the AV_FIFO_FLAG_AUTO_GROW flag * was not specified at FIFO creation, nothing is written and an error * is returned. * * Calling function is guaranteed to succeed if nb_elems <= av_fifo_can_write(f). * * @param f the FIFO buffer * @param buf Data to be written. nb_elems * av_fifo_elem_size(f) bytes will be * read from buf on success. * @param nb_elems number of elements to write into FIFO * * @return a non-negative number on success, a negative error code on failure */ int av_fifo_write(AVFifo *f, const void *buf, size_t nb_elems); /** * Write data from a user-provided callback into a FIFO. * * @param f the FIFO buffer * @param read_cb Callback supplying the data to the FIFO. May be called * multiple times. * @param opaque opaque user data to be provided to read_cb * @param nb_elems Should point to the maximum number of elements that can be * written. Will be updated to contain the number of elements * actually written. * * @return non-negative number on success, a negative error code on failure */ int av_fifo_write_from_cb(AVFifo *f, AVFifoCB read_cb, void *opaque, size_t *nb_elems); /** * Read data from a FIFO. * * In case nb_elems > av_fifo_can_read(f), nothing is read and an error * is returned. * * @param f the FIFO buffer * @param buf Buffer to store the data. nb_elems * av_fifo_elem_size(f) bytes * will be written into buf on success. * @param nb_elems number of elements to read from FIFO * * @return a non-negative number on success, a negative error code on failure */ int av_fifo_read(AVFifo *f, void *buf, size_t nb_elems); /** * Feed data from a FIFO into a user-provided callback. * * @param f the FIFO buffer * @param write_cb Callback the data will be supplied to. May be called * multiple times. * @param opaque opaque user data to be provided to write_cb * @param nb_elems Should point to the maximum number of elements that can be * read. Will be updated to contain the total number of elements * actually sent to the callback. * * @return non-negative number on success, a negative error code on failure */ int av_fifo_read_to_cb(AVFifo *f, AVFifoCB write_cb, void *opaque, size_t *nb_elems); /** * Read data from a FIFO without modifying FIFO state. * * Returns an error if an attempt is made to peek to nonexistent elements * (i.e. if offset + nb_elems is larger than av_fifo_can_read(f)). * * @param f the FIFO buffer * @param buf Buffer to store the data. nb_elems * av_fifo_elem_size(f) bytes * will be written into buf. * @param nb_elems number of elements to read from FIFO * @param offset number of initial elements to skip. * * @return a non-negative number on success, a negative error code on failure */ int av_fifo_peek(const AVFifo *f, void *buf, size_t nb_elems, size_t offset); /** * Feed data from a FIFO into a user-provided callback. * * @param f the FIFO buffer * @param write_cb Callback the data will be supplied to. May be called * multiple times. * @param opaque opaque user data to be provided to write_cb * @param nb_elems Should point to the maximum number of elements that can be * read. Will be updated to contain the total number of elements * actually sent to the callback. * @param offset number of initial elements to skip; offset + *nb_elems must not * be larger than av_fifo_can_read(f). * * @return a non-negative number on success, a negative error code on failure */ int av_fifo_peek_to_cb(const AVFifo *f, AVFifoCB write_cb, void *opaque, size_t *nb_elems, size_t offset); /** * Discard the specified amount of data from an AVFifo. * @param size number of elements to discard, MUST NOT be larger than * av_fifo_can_read(f) */ void av_fifo_drain2(AVFifo *f, size_t size); /* * Empty the AVFifo. * @param f AVFifo to reset */ void av_fifo_reset2(AVFifo *f); /** * Free an AVFifo and reset pointer to NULL. * @param f Pointer to an AVFifo to free. *f == NULL is allowed. */ void av_fifo_freep2(AVFifo **f); /** * @} */ #endif /* AVUTIL_FIFO_H */
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