cutils.c 2.0 KB

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  1. /*
  2. * various simple utilities for libavformat
  3. * Copyright (c) 2000, 2001, 2002 Fabrice Bellard
  4. *
  5. * This file is part of FFmpeg.
  6. *
  7. * FFmpeg is free software; you can redistribute it and/or
  8. * modify it under the terms of the GNU Lesser General Public
  9. * License as published by the Free Software Foundation; either
  10. * version 2.1 of the License, or (at your option) any later version.
  11. *
  12. * FFmpeg is distributed in the hope that it will be useful,
  13. * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14. * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  15. * Lesser General Public License for more details.
  16. *
  17. * You should have received a copy of the GNU Lesser General Public
  18. * License along with FFmpeg; if not, write to the Free Software
  19. * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20. */
  21. #include "avformat.h"
  22. #include "internal.h"
  23. #define ISLEAP(y) (((y) % 4 == 0) && (((y) % 100) != 0 || ((y) % 400) == 0))
  24. #define LEAPS_COUNT(y) ((y)/4 - (y)/100 + (y)/400)
  25. /* This is our own gmtime_r. It differs from its POSIX counterpart in a
  26. couple of places, though. */
  27. struct tm *brktimegm(time_t secs, struct tm *tm)
  28. {
  29. int days, y, ny, m;
  30. int md[] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
  31. days = secs / 86400;
  32. secs %= 86400;
  33. tm->tm_hour = secs / 3600;
  34. tm->tm_min = (secs % 3600) / 60;
  35. tm->tm_sec = secs % 60;
  36. /* oh well, may be someone some day will invent a formula for this stuff */
  37. y = 1970; /* start "guessing" */
  38. while (days > 365) {
  39. ny = (y + days/366);
  40. days -= (ny - y) * 365 + LEAPS_COUNT(ny - 1) - LEAPS_COUNT(y - 1);
  41. y = ny;
  42. }
  43. if (days==365 && !ISLEAP(y)) { days=0; y++; }
  44. md[1] = ISLEAP(y)?29:28;
  45. for (m=0; days >= md[m]; m++)
  46. days -= md[m];
  47. tm->tm_year = y; /* unlike gmtime_r we store complete year here */
  48. tm->tm_mon = m+1; /* unlike gmtime_r tm_mon is from 1 to 12 */
  49. tm->tm_mday = days+1;
  50. return tm;
  51. }