libavformat/cutils.c

   1 /*
   2  * various simple utilities for libavformat
   3  * Copyright (c) 2000, 2001, 2002 Fabrice Bellard
   4  *
   5  * This file is part of Libav.
   6  *
   7  * Libav 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  * Libav 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 Libav; 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
  24 /* add one element to a dynamic array */
  25 void ff_dynarray_add(intptr_t **tab_ptr, int *nb_ptr, intptr_t elem)
  26 {
  27     /* see similar avconv.c:grow_array() */
  28     int nb, nb_alloc;
  29     intptr_t *tab;
  30
  31     nb = *nb_ptr;
  32     tab = *tab_ptr;
  33     if ((nb & (nb - 1)) == 0) {
  34         if (nb == 0)
  35             nb_alloc = 1;
  36         else
  37             nb_alloc = nb * 2;
  38         tab = av_realloc(tab, nb_alloc * sizeof(intptr_t));
  39         *tab_ptr = tab;
  40     }
  41     tab[nb++] = elem;
  42     *nb_ptr = nb;
  43 }
  44
  45 #define ISLEAP(y) (((y) % 4 == 0) && (((y) % 100) != 0 || ((y) % 400) == 0))
  46 #define LEAPS_COUNT(y) ((y)/4 - (y)/100 + (y)/400)
  47
  48 /* This is our own gmtime_r. It differs from its POSIX counterpart in a
  49    couple of places, though. */
  50 struct tm *ff_brktimegm(time_t secs, struct tm *tm)
  51 {
  52     int days, y, ny, m;
  53     int md[] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
  54
  55     days = secs / 86400;
  56     secs %= 86400;
  57     tm->tm_hour = secs / 3600;
  58     tm->tm_min = (secs % 3600) / 60;
  59     tm->tm_sec =  secs % 60;
  60
  61     /* oh well, may be someone some day will invent a formula for this stuff */
  62     y = 1970; /* start "guessing" */
  63     while (days > 365) {
  64         ny = (y + days/366);
  65         days -= (ny - y) * 365 + LEAPS_COUNT(ny - 1) - LEAPS_COUNT(y - 1);
  66         y = ny;
  67     }
  68     if (days==365 && !ISLEAP(y)) { days=0; y++; }
  69     md[1] = ISLEAP(y)?29:28;
  70     for (m=0; days >= md[m]; m++)
  71          days -= md[m];
  72
  73     tm->tm_year = y;  /* unlike gmtime_r we store complete year here */
  74     tm->tm_mon = m+1; /* unlike gmtime_r tm_mon is from 1 to 12 */
  75     tm->tm_mday = days+1;
  76
  77     return tm;
  78 }