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2134
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1 /*
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2 * This file is part of FFmpeg.
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3 *
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4 * FFmpeg is free software; you can redistribute it and/or
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5 * modify it under the terms of the GNU Lesser General Public
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6 * License as published by the Free Software Foundation; either
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7 * version 2.1 of the License, or (at your option) any later version.
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8 *
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9 * FFmpeg is distributed in the hope that it will be useful,
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10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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12 * Lesser General Public License for more details.
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13 *
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14 * You should have received a copy of the GNU Lesser General Public
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15 * License along with FFmpeg; if not, write to the Free Software
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16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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17 */
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18
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19 /**
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20 * @file
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21 * a very simple circular buffer FIFO implementation
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22 */
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23
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24 #ifndef AVUTIL_FIFO_H
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25 #define AVUTIL_FIFO_H
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26
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27 #include <stdint.h>
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28 #include "avutil.h"
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29 #include "attributes.h"
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30
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31 typedef struct AVFifoBuffer {
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32 uint8_t *buffer;
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33 uint8_t *rptr, *wptr, *end;
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34 uint32_t rndx, wndx;
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35 } AVFifoBuffer;
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36
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37 /**
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38 * Initialize an AVFifoBuffer.
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39 * @param size of FIFO
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40 * @return AVFifoBuffer or NULL in case of memory allocation failure
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41 */
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42 AVFifoBuffer *av_fifo_alloc(unsigned int size);
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43
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44 /**
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45 * Free an AVFifoBuffer.
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46 * @param f AVFifoBuffer to free
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47 */
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48 void av_fifo_free(AVFifoBuffer *f);
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49
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50 /**
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51 * Reset the AVFifoBuffer to the state right after av_fifo_alloc, in particular it is emptied.
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52 * @param f AVFifoBuffer to reset
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53 */
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54 void av_fifo_reset(AVFifoBuffer *f);
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55
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56 /**
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57 * Return the amount of data in bytes in the AVFifoBuffer, that is the
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58 * amount of data you can read from it.
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59 * @param f AVFifoBuffer to read from
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60 * @return size
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61 */
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62 int av_fifo_size(AVFifoBuffer *f);
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63
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64 /**
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65 * Return the amount of space in bytes in the AVFifoBuffer, that is the
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66 * amount of data you can write into it.
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67 * @param f AVFifoBuffer to write into
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68 * @return size
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69 */
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70 int av_fifo_space(AVFifoBuffer *f);
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71
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72 /**
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73 * Feed data from an AVFifoBuffer to a user-supplied callback.
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74 * @param f AVFifoBuffer to read from
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75 * @param buf_size number of bytes to read
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76 * @param func generic read function
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77 * @param dest data destination
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78 */
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79 int av_fifo_generic_read(AVFifoBuffer *f, void *dest, int buf_size, void (*func)(void*, void*, int));
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80
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81 /**
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82 * Feed data from a user-supplied callback to an AVFifoBuffer.
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83 * @param f AVFifoBuffer to write to
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84 * @param src data source; non-const since it may be used as a
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85 * modifiable context by the function defined in func
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86 * @param size number of bytes to write
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87 * @param func generic write function; the first parameter is src,
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88 * the second is dest_buf, the third is dest_buf_size.
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89 * func must return the number of bytes written to dest_buf, or <= 0 to
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90 * indicate no more data available to write.
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91 * If func is NULL, src is interpreted as a simple byte array for source data.
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92 * @return the number of bytes written to the FIFO
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93 */
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94 int av_fifo_generic_write(AVFifoBuffer *f, void *src, int size, int (*func)(void*, void*, int));
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95
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96 /**
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97 * Resize an AVFifoBuffer.
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98 * In case of reallocation failure, the old FIFO is kept unchanged.
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99 *
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100 * @param f AVFifoBuffer to resize
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101 * @param size new AVFifoBuffer size in bytes
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102 * @return <0 for failure, >=0 otherwise
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103 */
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104 int av_fifo_realloc2(AVFifoBuffer *f, unsigned int size);
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105
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106 /**
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107 * Enlarge an AVFifoBuffer.
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108 * In case of reallocation failure, the old FIFO is kept unchanged.
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109 * The new fifo size may be larger than the requested size.
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110 *
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111 * @param f AVFifoBuffer to resize
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112 * @param additional_space the amount of space in bytes to allocate in addition to av_fifo_size()
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113 * @return <0 for failure, >=0 otherwise
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114 */
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115 int av_fifo_grow(AVFifoBuffer *f, unsigned int additional_space);
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116
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117 /**
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118 * Read and discard the specified amount of data from an AVFifoBuffer.
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119 * @param f AVFifoBuffer to read from
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120 * @param size amount of data to read in bytes
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121 */
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122 void av_fifo_drain(AVFifoBuffer *f, int size);
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123
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124 /**
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125 * Return a pointer to the data stored in a FIFO buffer at a certain offset.
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126 * The FIFO buffer is not modified.
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127 *
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128 * @param f AVFifoBuffer to peek at, f must be non-NULL
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129 * @param offs an offset in bytes, its absolute value must be less
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130 * than the used buffer size or the returned pointer will
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131 * point outside to the buffer data.
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132 * The used buffer size can be checked with av_fifo_size().
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133 */
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134 static inline uint8_t *av_fifo_peek2(const AVFifoBuffer *f, int offs)
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135 {
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136 uint8_t *ptr = f->rptr + offs;
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137 if (ptr >= f->end)
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138 ptr = f->buffer + (ptr - f->end);
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139 else if (ptr < f->buffer)
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140 ptr = f->end - (f->buffer - ptr);
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141 return ptr;
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142 }
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143
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144 #endif /* AVUTIL_FIFO_H */
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