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 30typedef 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 */ 41AVFifoBuffer *av_fifo_alloc(unsigned int size); 42 43/** 44 * Free an AVFifoBuffer. 45 * @param f AVFifoBuffer to free 46 */ 47void 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 */ 53void 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 */ 61int 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 */ 69int 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 */ 78int 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 */ 93int 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 */ 101int 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 */ 108void 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 */ 120static 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 */ 134attribute_deprecated 135static 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 */ 142