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 #if FF_API_AV_FIFO_PEEK

   132 /**

   133  * @deprecated Use av_fifo_peek2() instead.

   134  */

   135 attribute_deprecated

   136 static inline uint8_t av_fifo_peek(AVFifoBuffer *f, int offs)

   137 {

   138     return *av_fifo_peek2(f, offs);

   139 }

   140 #endif

   141 

   142 #endif /* AVUTIL_FIFO_H */