tor-browser

The Tor Browser
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fifo.h (4344B)

      1 /*
      2 * This file is part of Libav.
      3 *
      4 * Libav 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 * Libav 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 Libav; 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 
     30 typedef struct AVFifoBuffer {
     31    uint8_t *buffer;
     32    uint8_t *rptr, *wptr, *end;
     33    uint32_t rndx, wndx;
     34 } AVFifoBuffer;
     35 
     36 /**
     37 * Initialize an AVFifoBuffer.
     38 * @param size of FIFO
     39 * @return AVFifoBuffer or NULL in case of memory allocation failure
     40 */
     41 AVFifoBuffer *av_fifo_alloc(unsigned int size);
     42 
     43 /**
     44 * Free an AVFifoBuffer.
     45 * @param f AVFifoBuffer to free
     46 */
     47 void av_fifo_free(AVFifoBuffer *f);
     48 
     49 /**
     50 * Reset the AVFifoBuffer to the state right after av_fifo_alloc, in particular it is emptied.
     51 * @param f AVFifoBuffer to reset
     52 */
     53 void av_fifo_reset(AVFifoBuffer *f);
     54 
     55 /**
     56 * Return the amount of data in bytes in the AVFifoBuffer, that is the
     57 * amount of data you can read from it.
     58 * @param f AVFifoBuffer to read from
     59 * @return size
     60 */
     61 int av_fifo_size(AVFifoBuffer *f);
     62 
     63 /**
     64 * Return the amount of space in bytes in the AVFifoBuffer, that is the
     65 * amount of data you can write into it.
     66 * @param f AVFifoBuffer to write into
     67 * @return size
     68 */
     69 int av_fifo_space(AVFifoBuffer *f);
     70 
     71 /**
     72 * Feed data from an AVFifoBuffer to a user-supplied callback.
     73 * @param f AVFifoBuffer to read from
     74 * @param buf_size number of bytes to read
     75 * @param func generic read function
     76 * @param dest data destination
     77 */
     78 int av_fifo_generic_read(AVFifoBuffer *f, void *dest, int buf_size, void (*func)(void*, void*, int));
     79 
     80 /**
     81 * Feed data from a user-supplied callback to an AVFifoBuffer.
     82 * @param f AVFifoBuffer to write to
     83 * @param src data source; non-const since it may be used as a
     84 * modifiable context by the function defined in func
     85 * @param size number of bytes to write
     86 * @param func generic write function; the first parameter is src,
     87 * the second is dest_buf, the third is dest_buf_size.
     88 * func must return the number of bytes written to dest_buf, or <= 0 to
     89 * indicate no more data available to write.
     90 * If func is NULL, src is interpreted as a simple byte array for source data.
     91 * @return the number of bytes written to the FIFO
     92 */
     93 int av_fifo_generic_write(AVFifoBuffer *f, void *src, int size, int (*func)(void*, void*, int));
     94 
     95 /**
     96 * Resize an AVFifoBuffer.
     97 * @param f AVFifoBuffer to resize
     98 * @param size new AVFifoBuffer size in bytes
     99 * @return <0 for failure, >=0 otherwise
    100 */
    101 int av_fifo_realloc2(AVFifoBuffer *f, unsigned int size);
    102 
    103 /**
    104 * Read and discard the specified amount of data from an AVFifoBuffer.
    105 * @param f AVFifoBuffer to read from
    106 * @param size amount of data to read in bytes
    107 */
    108 void av_fifo_drain(AVFifoBuffer *f, int size);
    109 
    110 /**
    111 * Return a pointer to the data stored in a FIFO buffer at a certain offset.
    112 * The FIFO buffer is not modified.
    113 *
    114 * @param f    AVFifoBuffer to peek at, f must be non-NULL
    115 * @param offs an offset in bytes, its absolute value must be less
    116 *             than the used buffer size or the returned pointer will
    117 *             point outside to the buffer data.
    118 *             The used buffer size can be checked with av_fifo_size().
    119 */
    120 static inline uint8_t *av_fifo_peek2(const AVFifoBuffer *f, int offs)
    121 {
    122    uint8_t *ptr = f->rptr + offs;
    123    if (ptr >= f->end)
    124        ptr = f->buffer + (ptr - f->end);
    125    else if (ptr < f->buffer)
    126        ptr = f->end - (f->buffer - ptr);
    127    return ptr;
    128 }
    129 
    130 #if FF_API_AV_FIFO_PEEK
    131 /**
    132 * @deprecated Use av_fifo_peek2() instead.
    133 */
    134 attribute_deprecated
    135 static inline uint8_t av_fifo_peek(AVFifoBuffer *f, int offs)
    136 {
    137    return *av_fifo_peek2(f, offs);
    138 }
    139 #endif
    140 
    141 #endif /* AVUTIL_FIFO_H */