fifo.h 4.7 KB

123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154
  1. /*
  2. * This file is part of FFmpeg.
  3. *
  4. * FFmpeg 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. * FFmpeg 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 FFmpeg; if not, write to the Free Software
  16. * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  17. */
  18. /**
  19. * @file
  20. * a very simple circular buffer FIFO implementation
  21. */
  22. #ifndef AVUTIL_FIFO_H
  23. #define AVUTIL_FIFO_H
  24. #include <stdint.h>
  25. #include "avutil.h"
  26. typedef struct AVFifoBuffer {
  27. uint8_t *buffer;
  28. uint8_t *rptr, *wptr, *end;
  29. uint32_t rndx, wndx;
  30. } AVFifoBuffer;
  31. /**
  32. * Initialize an AVFifoBuffer.
  33. * @param size of FIFO
  34. * @return AVFifoBuffer or NULL in case of memory allocation failure
  35. */
  36. AVFifoBuffer *av_fifo_alloc(unsigned int size);
  37. /**
  38. * Free an AVFifoBuffer.
  39. * @param f AVFifoBuffer to free
  40. */
  41. void av_fifo_free(AVFifoBuffer *f);
  42. /**
  43. * Reset the AVFifoBuffer to the state right after av_fifo_alloc, in particular it is emptied.
  44. * @param f AVFifoBuffer to reset
  45. */
  46. void av_fifo_reset(AVFifoBuffer *f);
  47. /**
  48. * Return the amount of data in bytes in the AVFifoBuffer, that is the
  49. * amount of data you can read from it.
  50. * @param f AVFifoBuffer to read from
  51. * @return size
  52. */
  53. int av_fifo_size(AVFifoBuffer *f);
  54. /**
  55. * Return the amount of space in bytes in the AVFifoBuffer, that is the
  56. * amount of data you can write into it.
  57. * @param f AVFifoBuffer to write into
  58. * @return size
  59. */
  60. int av_fifo_space(AVFifoBuffer *f);
  61. /**
  62. * Feed data from an AVFifoBuffer to a user-supplied callback.
  63. * @param f AVFifoBuffer to read from
  64. * @param buf_size number of bytes to read
  65. * @param func generic read function
  66. * @param dest data destination
  67. */
  68. int av_fifo_generic_read(AVFifoBuffer *f, void *dest, int buf_size, void (*func)(void*, void*, int));
  69. /**
  70. * Feed data from a user-supplied callback to an AVFifoBuffer.
  71. * @param f AVFifoBuffer to write to
  72. * @param src data source; non-const since it may be used as a
  73. * modifiable context by the function defined in func
  74. * @param size number of bytes to write
  75. * @param func generic write function; the first parameter is src,
  76. * the second is dest_buf, the third is dest_buf_size.
  77. * func must return the number of bytes written to dest_buf, or <= 0 to
  78. * indicate no more data available to write.
  79. * If func is NULL, src is interpreted as a simple byte array for source data.
  80. * @return the number of bytes written to the FIFO
  81. */
  82. int av_fifo_generic_write(AVFifoBuffer *f, void *src, int size, int (*func)(void*, void*, int));
  83. /**
  84. * Resize an AVFifoBuffer.
  85. * In case of reallocation failure, the old FIFO is kept unchanged.
  86. *
  87. * @param f AVFifoBuffer to resize
  88. * @param size new AVFifoBuffer size in bytes
  89. * @return <0 for failure, >=0 otherwise
  90. */
  91. int av_fifo_realloc2(AVFifoBuffer *f, unsigned int size);
  92. /**
  93. * Enlarge an AVFifoBuffer.
  94. * In case of reallocation failure, the old FIFO is kept unchanged.
  95. * The new fifo size may be larger than the requested size.
  96. *
  97. * @param f AVFifoBuffer to resize
  98. * @param additional_space the amount of space in bytes to allocate in addition to av_fifo_size()
  99. * @return <0 for failure, >=0 otherwise
  100. */
  101. int av_fifo_grow(AVFifoBuffer *f, unsigned int additional_space);
  102. /**
  103. * Read and discard the specified amount of data from an AVFifoBuffer.
  104. * @param f AVFifoBuffer to read from
  105. * @param size amount of data to read in bytes
  106. */
  107. void av_fifo_drain(AVFifoBuffer *f, int size);
  108. /**
  109. * Return a pointer to the data stored in a FIFO buffer at a certain offset.
  110. * The FIFO buffer is not modified.
  111. *
  112. * @param f AVFifoBuffer to peek at, f must be non-NULL
  113. * @param offs an offset in bytes, its absolute value must be less
  114. * than the used buffer size or the returned pointer will
  115. * point outside to the buffer data.
  116. * The used buffer size can be checked with av_fifo_size().
  117. */
  118. static inline uint8_t *av_fifo_peek2(const AVFifoBuffer *f, int offs)
  119. {
  120. uint8_t *ptr = f->rptr + offs;
  121. if (ptr >= f->end)
  122. ptr = f->buffer + (ptr - f->end);
  123. else if (ptr < f->buffer)
  124. ptr = f->end - (f->buffer - ptr);
  125. return ptr;
  126. }
  127. #if FF_API_AV_FIFO_PEEK
  128. /**
  129. * @deprecated Use av_fifo_peek2() instead.
  130. */
  131. attribute_deprecated
  132. static inline uint8_t av_fifo_peek(AVFifoBuffer *f, int offs)
  133. {
  134. return *av_fifo_peek2(f, offs);
  135. }
  136. #endif
  137. #endif /* AVUTIL_FIFO_H */