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  1. /*
  2.  * This file is part of FFmpeg.
  3.  *
  4.  * FFmpeg is free software; you can redistribute it and/or
  5.  * modify it under the terms of the GNU Lesser General Public
  6.  * License as published by the Free Software Foundation; either
  7.  * version 2.1 of the License, or (at your option) any later version.
  8.  *
  9.  * FFmpeg is distributed in the hope that it will be useful,
  10.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12.  * Lesser General Public License for more details.
  13.  *
  14.  * You should have received a copy of the GNU Lesser General Public
  15.  * License along with FFmpeg; if not, write to the Free Software
  16.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  17.  */
  18.  
  19. /**
  20.  * @file
  21.  * a very simple circular buffer FIFO implementation
  22.  */
  23.  
  24. #ifndef AVUTIL_FIFO_H
  25. #define AVUTIL_FIFO_H
  26.  
  27. #include <stdint.h>
  28. #include "avutil.h"
  29. #include "attributes.h"
  30.  
  31. typedef struct AVFifoBuffer {
  32.     uint8_t *buffer;
  33.     uint8_t *rptr, *wptr, *end;
  34.     uint32_t rndx, wndx;
  35. } AVFifoBuffer;
  36.  
  37. /**
  38.  * Initialize an AVFifoBuffer.
  39.  * @param size of FIFO
  40.  * @return AVFifoBuffer or NULL in case of memory allocation failure
  41.  */
  42. AVFifoBuffer *av_fifo_alloc(unsigned int size);
  43.  
  44. /**
  45.  * Free an AVFifoBuffer.
  46.  * @param f AVFifoBuffer to free
  47.  */
  48. void av_fifo_free(AVFifoBuffer *f);
  49.  
  50. /**
  51.  * Reset the AVFifoBuffer to the state right after av_fifo_alloc, in particular it is emptied.
  52.  * @param f AVFifoBuffer to reset
  53.  */
  54. void av_fifo_reset(AVFifoBuffer *f);
  55.  
  56. /**
  57.  * Return the amount of data in bytes in the AVFifoBuffer, that is the
  58.  * amount of data you can read from it.
  59.  * @param f AVFifoBuffer to read from
  60.  * @return size
  61.  */
  62. int av_fifo_size(AVFifoBuffer *f);
  63.  
  64. /**
  65.  * Return the amount of space in bytes in the AVFifoBuffer, that is the
  66.  * amount of data you can write into it.
  67.  * @param f AVFifoBuffer to write into
  68.  * @return size
  69.  */
  70. int av_fifo_space(AVFifoBuffer *f);
  71.  
  72. /**
  73.  * Feed data from an AVFifoBuffer to a user-supplied callback.
  74.  * @param f AVFifoBuffer to read from
  75.  * @param buf_size number of bytes to read
  76.  * @param func generic read function
  77.  * @param dest data destination
  78.  */
  79. int av_fifo_generic_read(AVFifoBuffer *f, void *dest, int buf_size, void (*func)(void*, void*, int));
  80.  
  81. /**
  82.  * Feed data from a user-supplied callback to an AVFifoBuffer.
  83.  * @param f AVFifoBuffer to write to
  84.  * @param src data source; non-const since it may be used as a
  85.  * modifiable context by the function defined in func
  86.  * @param size number of bytes to write
  87.  * @param func generic write function; the first parameter is src,
  88.  * the second is dest_buf, the third is dest_buf_size.
  89.  * func must return the number of bytes written to dest_buf, or <= 0 to
  90.  * indicate no more data available to write.
  91.  * If func is NULL, src is interpreted as a simple byte array for source data.
  92.  * @return the number of bytes written to the FIFO
  93.  */
  94. int av_fifo_generic_write(AVFifoBuffer *f, void *src, int size, int (*func)(void*, void*, int));
  95.  
  96. /**
  97.  * Resize an AVFifoBuffer.
  98.  * In case of reallocation failure, the old FIFO is kept unchanged.
  99.  *
  100.  * @param f AVFifoBuffer to resize
  101.  * @param size new AVFifoBuffer size in bytes
  102.  * @return <0 for failure, >=0 otherwise
  103.  */
  104. int av_fifo_realloc2(AVFifoBuffer *f, unsigned int size);
  105.  
  106. /**
  107.  * Enlarge an AVFifoBuffer.
  108.  * In case of reallocation failure, the old FIFO is kept unchanged.
  109.  * The new fifo size may be larger than the requested size.
  110.  *
  111.  * @param f AVFifoBuffer to resize
  112.  * @param additional_space the amount of space in bytes to allocate in addition to av_fifo_size()
  113.  * @return <0 for failure, >=0 otherwise
  114.  */
  115. int av_fifo_grow(AVFifoBuffer *f, unsigned int additional_space);
  116.  
  117. /**
  118.  * Read and discard the specified amount of data from an AVFifoBuffer.
  119.  * @param f AVFifoBuffer to read from
  120.  * @param size amount of data to read in bytes
  121.  */
  122. void av_fifo_drain(AVFifoBuffer *f, int size);
  123.  
  124. /**
  125.  * Return a pointer to the data stored in a FIFO buffer at a certain offset.
  126.  * The FIFO buffer is not modified.
  127.  *
  128.  * @param f    AVFifoBuffer to peek at, f must be non-NULL
  129.  * @param offs an offset in bytes, its absolute value must be less
  130.  *             than the used buffer size or the returned pointer will
  131.  *             point outside to the buffer data.
  132.  *             The used buffer size can be checked with av_fifo_size().
  133.  */
  134. static inline uint8_t *av_fifo_peek2(const AVFifoBuffer *f, int offs)
  135. {
  136.     uint8_t *ptr = f->rptr + offs;
  137.     if (ptr >= f->end)
  138.         ptr = f->buffer + (ptr - f->end);
  139.     else if (ptr < f->buffer)
  140.         ptr = f->end - (f->buffer - ptr);
  141.     return ptr;
  142. }
  143.  
  144. #endif /* AVUTIL_FIFO_H */
  145.