tor-browser

The Tor Browser
git clone https://git.dasho.dev/tor-browser.git
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fifo.h (4161B)

      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 #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 * @param f AVFifoBuffer to resize
     99 * @param size new AVFifoBuffer size in bytes
    100 * @return <0 for failure, >=0 otherwise
    101 */
    102 int av_fifo_realloc2(AVFifoBuffer *f, unsigned int size);
    103 
    104 /**
    105 * Read and discard the specified amount of data from an AVFifoBuffer.
    106 * @param f AVFifoBuffer to read from
    107 * @param size amount of data to read in bytes
    108 */
    109 void av_fifo_drain(AVFifoBuffer *f, int size);
    110 
    111 /**
    112 * Return a pointer to the data stored in a FIFO buffer at a certain offset.
    113 * The FIFO buffer is not modified.
    114 *
    115 * @param f    AVFifoBuffer to peek at, f must be non-NULL
    116 * @param offs an offset in bytes, its absolute value must be less
    117 *             than the used buffer size or the returned pointer will
    118 *             point outside to the buffer data.
    119 *             The used buffer size can be checked with av_fifo_size().
    120 */
    121 static inline uint8_t *av_fifo_peek2(const AVFifoBuffer *f, int offs)
    122 {
    123    uint8_t *ptr = f->rptr + offs;
    124    if (ptr >= f->end)
    125        ptr = f->buffer + (ptr - f->end);
    126    else if (ptr < f->buffer)
    127        ptr = f->end - (f->buffer - ptr);
    128    return ptr;
    129 }
    130 
    131 #endif /* AVUTIL_FIFO_H */