fifo.c 4.5 KB

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  1. /*
  2. * a very simple circular buffer FIFO implementation
  3. * Copyright (c) 2000, 2001, 2002 Fabrice Bellard
  4. * Copyright (c) 2006 Roman Shaposhnik
  5. *
  6. * This file is part of FFmpeg.
  7. *
  8. * FFmpeg is free software; you can redistribute it and/or
  9. * modify it under the terms of the GNU Lesser General Public
  10. * License as published by the Free Software Foundation; either
  11. * version 2.1 of the License, or (at your option) any later version.
  12. *
  13. * FFmpeg is distributed in the hope that it will be useful,
  14. * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15. * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16. * Lesser General Public License for more details.
  17. *
  18. * You should have received a copy of the GNU Lesser General Public
  19. * License along with FFmpeg; if not, write to the Free Software
  20. * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21. */
  22. #include "common.h"
  23. #include "fifo.h"
  24. AVFifoBuffer *av_fifo_alloc(unsigned int size)
  25. {
  26. AVFifoBuffer *f= av_mallocz(sizeof(AVFifoBuffer));
  27. if (!f)
  28. return NULL;
  29. f->buffer = av_malloc(size);
  30. f->end = f->buffer + size;
  31. av_fifo_reset(f);
  32. if (!f->buffer)
  33. av_freep(&f);
  34. return f;
  35. }
  36. void av_fifo_free(AVFifoBuffer *f)
  37. {
  38. if (f) {
  39. av_freep(&f->buffer);
  40. av_free(f);
  41. }
  42. }
  43. void av_fifo_reset(AVFifoBuffer *f)
  44. {
  45. f->wptr = f->rptr = f->buffer;
  46. f->wndx = f->rndx = 0;
  47. }
  48. int av_fifo_size(AVFifoBuffer *f)
  49. {
  50. return (uint32_t)(f->wndx - f->rndx);
  51. }
  52. int av_fifo_space(AVFifoBuffer *f)
  53. {
  54. return f->end - f->buffer - av_fifo_size(f);
  55. }
  56. int av_fifo_realloc2(AVFifoBuffer *f, unsigned int new_size)
  57. {
  58. unsigned int old_size = f->end - f->buffer;
  59. if (old_size < new_size) {
  60. int len = av_fifo_size(f);
  61. AVFifoBuffer *f2 = av_fifo_alloc(new_size);
  62. if (!f2)
  63. return AVERROR(ENOMEM);
  64. av_fifo_generic_read(f, f2->buffer, len, NULL);
  65. f2->wptr += len;
  66. f2->wndx += len;
  67. av_free(f->buffer);
  68. *f = *f2;
  69. av_free(f2);
  70. }
  71. return 0;
  72. }
  73. int av_fifo_grow(AVFifoBuffer *f, unsigned int size)
  74. {
  75. unsigned int old_size = f->end - f->buffer;
  76. if(size + (unsigned)av_fifo_size(f) < size)
  77. return AVERROR(EINVAL);
  78. size += av_fifo_size(f);
  79. if (old_size < size)
  80. return av_fifo_realloc2(f, FFMAX(size, 2*size));
  81. return 0;
  82. }
  83. // src must NOT be const as it can be a context for func that may need updating (like a pointer or byte counter)
  84. int av_fifo_generic_write(AVFifoBuffer *f, void *src, int size, int (*func)(void*, void*, int))
  85. {
  86. int total = size;
  87. uint32_t wndx= f->wndx;
  88. uint8_t *wptr= f->wptr;
  89. do {
  90. int len = FFMIN(f->end - wptr, size);
  91. if (func) {
  92. if (func(src, wptr, len) <= 0)
  93. break;
  94. } else {
  95. memcpy(wptr, src, len);
  96. src = (uint8_t*)src + len;
  97. }
  98. // Write memory barrier needed for SMP here in theory
  99. wptr += len;
  100. if (wptr >= f->end)
  101. wptr = f->buffer;
  102. wndx += len;
  103. size -= len;
  104. } while (size > 0);
  105. f->wndx= wndx;
  106. f->wptr= wptr;
  107. return total - size;
  108. }
  109. int av_fifo_generic_read(AVFifoBuffer *f, void *dest, int buf_size, void (*func)(void*, void*, int))
  110. {
  111. // Read memory barrier needed for SMP here in theory
  112. do {
  113. int len = FFMIN(f->end - f->rptr, buf_size);
  114. if(func) func(dest, f->rptr, len);
  115. else{
  116. memcpy(dest, f->rptr, len);
  117. dest = (uint8_t*)dest + len;
  118. }
  119. // memory barrier needed for SMP here in theory
  120. av_fifo_drain(f, len);
  121. buf_size -= len;
  122. } while (buf_size > 0);
  123. return 0;
  124. }
  125. /** Discard data from the FIFO. */
  126. void av_fifo_drain(AVFifoBuffer *f, int size)
  127. {
  128. f->rptr += size;
  129. if (f->rptr >= f->end)
  130. f->rptr -= f->end - f->buffer;
  131. f->rndx += size;
  132. }
  133. #ifdef TEST
  134. int main(void)
  135. {
  136. /* create a FIFO buffer */
  137. AVFifoBuffer *fifo = av_fifo_alloc(13 * sizeof(int));
  138. int i, j, n;
  139. /* fill data */
  140. for (i = 0; av_fifo_space(fifo) >= sizeof(int); i++)
  141. av_fifo_generic_write(fifo, &i, sizeof(int), NULL);
  142. /* peek at FIFO */
  143. n = av_fifo_size(fifo)/sizeof(int);
  144. for (i = -n+1; i < n; i++) {
  145. int *v = (int *)av_fifo_peek2(fifo, i*sizeof(int));
  146. printf("%d: %d\n", i, *v);
  147. }
  148. printf("\n");
  149. /* read data */
  150. for (i = 0; av_fifo_size(fifo) >= sizeof(int); i++) {
  151. av_fifo_generic_read(fifo, &j, sizeof(int), NULL);
  152. printf("%d ", j);
  153. }
  154. printf("\n");
  155. av_fifo_free(fifo);
  156. return 0;
  157. }
  158. #endif