libavutil/fifo.h

   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 libavutil/fifo.h
  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 "common.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  * Initializes an AVFifoBuffer.
  39  * @param size of FIFO
  40  * @return AVFifoBuffer or NULL if mem allocation failure
  41  */
  42 AVFifoBuffer *av_fifo_alloc(unsigned int size);
  43
  44 /**
  45  * Frees an AVFifoBuffer.
  46  * @param *f AVFifoBuffer to free
  47  */
  48 void av_fifo_free(AVFifoBuffer *f);
  49
  50 /**
  51  * Resets 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  * Returns 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  * Feeds data from an AVFifoBuffer to a user-supplied callback.
  66  * @param *f AVFifoBuffer to read from
  67  * @param buf_size number of bytes to read
  68  * @param *func generic read function
  69  * @param *dest data destination
  70  */
  71 int av_fifo_generic_read(AVFifoBuffer *f, void *dest, int buf_size, void (*func)(void*, void*, int));
  72
  73 /**
  74  * Feeds data from a user-supplied callback to an AVFifoBuffer.
  75  * @param *f AVFifoBuffer to write to
  76  * @param *src data source
  77  * @param size number of bytes to write
  78  * @param *func generic write function; the first parameter is src,
  79  * the second is dest_buf, the third is dest_buf_size.
  80  * func must return the number of bytes written to dest_buf, or <= 0 to
  81  * indicate no more data available to write.
  82  * If func is NULL, src is interpreted as a simple byte array for source data.
  83  * @return the number of bytes written to the FIFO
  84  */
  85 int av_fifo_generic_write(AVFifoBuffer *f, void *src, int size, int (*func)(void*, void*, int));
  86
  87 /**
  88  * Resizes an AVFifoBuffer.
  89  * @param *f AVFifoBuffer to resize
  90  * @param size new AVFifoBuffer size in bytes
  91  * @return <0 for failure, >=0 otherwise
  92  */
  93 int av_fifo_realloc2(AVFifoBuffer *f, unsigned int size);
  94
  95 /**
  96  * Reads and discards the specified amount of data from an AVFifoBuffer.
  97  * @param *f AVFifoBuffer to read from
  98  * @param size amount of data to read in bytes
  99  */
 100 void av_fifo_drain(AVFifoBuffer *f, int size);
 101
 102 static inline uint8_t av_fifo_peek(AVFifoBuffer *f, int offs)
 103 {
 104     uint8_t *ptr = f->rptr + offs;
 105     if (ptr >= f->end)
 106         ptr -= f->end - f->buffer;
 107     return *ptr;
 108 }
 109 #endif /* AVUTIL_FIFO_H */