libavformat/cutils.c

   1 /*
   2  * Various simple utilities for ffmpeg system
   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
  23 /* add one element to a dynamic array */
  24 void ff_dynarray_add(intptr_t **tab_ptr, int *nb_ptr, intptr_t elem)
  25 {
  26     int nb, nb_alloc;
  27     intptr_t *tab;
  28
  29     nb = *nb_ptr;
  30     tab = *tab_ptr;
  31     if ((nb & (nb - 1)) == 0) {
  32         if (nb == 0)
  33             nb_alloc = 1;
  34         else
  35             nb_alloc = nb * 2;
  36         tab = av_realloc(tab, nb_alloc * sizeof(intptr_t));
  37         *tab_ptr = tab;
  38     }
  39     tab[nb++] = elem;
  40     *nb_ptr = nb;
  41 }
  42
  43 time_t mktimegm(struct tm *tm)
  44 {
  45     time_t t;
  46
  47     int y = tm->tm_year + 1900, m = tm->tm_mon + 1, d = tm->tm_mday;
  48
  49     if (m < 3) {
  50         m += 12;
  51         y--;
  52     }
  53
  54     t = 86400 *
  55         (d + (153 * m - 457) / 5 + 365 * y + y / 4 - y / 100 + y / 400 - 719469);
  56
  57     t += 3600 * tm->tm_hour + 60 * tm->tm_min + tm->tm_sec;
  58
  59     return t;
  60 }
  61
  62 #define ISLEAP(y) (((y) % 4 == 0) && (((y) % 100) != 0 || ((y) % 400) == 0))
  63 #define LEAPS_COUNT(y) ((y)/4 - (y)/100 + (y)/400)
  64
  65 /* This is our own gmtime_r. It differs from its POSIX counterpart in a
  66    couple of places, though. */
  67 struct tm *brktimegm(time_t secs, struct tm *tm)
  68 {
  69     int days, y, ny, m;
  70     int md[] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
  71
  72     days = secs / 86400;
  73     secs %= 86400;
  74     tm->tm_hour = secs / 3600;
  75     tm->tm_min = (secs % 3600) / 60;
  76     tm->tm_sec =  secs % 60;
  77
  78     /* oh well, may be someone some day will invent a formula for this stuff */
  79     y = 1970; /* start "guessing" */
  80     while (days > 365) {
  81         ny = (y + days/366);
  82         days -= (ny - y) * 365 + LEAPS_COUNT(ny - 1) - LEAPS_COUNT(y - 1);
  83         y = ny;
  84     }
  85     if (days==365 && !ISLEAP(y)) { days=0; y++; }
  86     md[1] = ISLEAP(y)?29:28;
  87     for (m=0; days >= md[m]; m++)
  88          days -= md[m];
  89
  90     tm->tm_year = y;  /* unlike gmtime_r we store complete year here */
  91     tm->tm_mon = m+1; /* unlike gmtime_r tm_mon is from 1 to 12 */
  92     tm->tm_mday = days+1;
  93
  94     return tm;
  95 }
  96
  97 /* get a positive number between n_min and n_max, for a maximum length
  98    of len_max. Return -1 if error. */
  99 static int date_get_num(const char **pp,
 100                         int n_min, int n_max, int len_max)
 101 {
 102     int i, val, c;
 103     const char *p;
 104
 105     p = *pp;
 106     val = 0;
 107     for(i = 0; i < len_max; i++) {
 108         c = *p;
 109         if (!isdigit(c))
 110             break;
 111         val = (val * 10) + c - '0';
 112         p++;
 113     }
 114     /* no number read ? */
 115     if (p == *pp)
 116         return -1;
 117     if (val < n_min || val > n_max)
 118         return -1;
 119     *pp = p;
 120     return val;
 121 }
 122
 123 /* small strptime for ffmpeg */
 124 const char *small_strptime(const char *p, const char *fmt,
 125                            struct tm *dt)
 126 {
 127     int c, val;
 128
 129     for(;;) {
 130         c = *fmt++;
 131         if (c == '\0') {
 132             return p;
 133         } else if (c == '%') {
 134             c = *fmt++;
 135             switch(c) {
 136             case 'H':
 137                 val = date_get_num(&p, 0, 23, 2);
 138                 if (val == -1)
 139                     return NULL;
 140                 dt->tm_hour = val;
 141                 break;
 142             case 'M':
 143                 val = date_get_num(&p, 0, 59, 2);
 144                 if (val == -1)
 145                     return NULL;
 146                 dt->tm_min = val;
 147                 break;
 148             case 'S':
 149                 val = date_get_num(&p, 0, 59, 2);
 150                 if (val == -1)
 151                     return NULL;
 152                 dt->tm_sec = val;
 153                 break;
 154             case 'Y':
 155                 val = date_get_num(&p, 0, 9999, 4);
 156                 if (val == -1)
 157                     return NULL;
 158                 dt->tm_year = val - 1900;
 159                 break;
 160             case 'm':
 161                 val = date_get_num(&p, 1, 12, 2);
 162                 if (val == -1)
 163                     return NULL;
 164                 dt->tm_mon = val - 1;
 165                 break;
 166             case 'd':
 167                 val = date_get_num(&p, 1, 31, 2);
 168                 if (val == -1)
 169                     return NULL;
 170                 dt->tm_mday = val;
 171                 break;
 172             case '%':
 173                 goto match;
 174             default:
 175                 return NULL;
 176             }
 177         } else {
 178         match:
 179             if (c != *p)
 180                 return NULL;
 181             p++;
 182         }
 183     }
 184     return p;
 185 }
 186