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libavformat/cutils.c

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00001 /*
00002  * Various simple utilities for ffmpeg system
00003  * Copyright (c) 2000, 2001, 2002 Fabrice Bellard
00004  *
00005  * This file is part of FFmpeg.
00006  *
00007  * FFmpeg is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU Lesser General Public
00009  * License as published by the Free Software Foundation; either
00010  * version 2.1 of the License, or (at your option) any later version.
00011  *
00012  * FFmpeg is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015  * Lesser General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU Lesser General Public
00018  * License along with FFmpeg; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 #include "avformat.h"
00022 #include "internal.h"
00023 
00024 /* add one element to a dynamic array */
00025 void ff_dynarray_add(intptr_t **tab_ptr, int *nb_ptr, intptr_t elem)
00026 {
00027     int nb, nb_alloc;
00028     intptr_t *tab;
00029 
00030     nb = *nb_ptr;
00031     tab = *tab_ptr;
00032     if ((nb & (nb - 1)) == 0) {
00033         if (nb == 0)
00034             nb_alloc = 1;
00035         else
00036             nb_alloc = nb * 2;
00037         tab = av_realloc(tab, nb_alloc * sizeof(intptr_t));
00038         *tab_ptr = tab;
00039     }
00040     tab[nb++] = elem;
00041     *nb_ptr = nb;
00042 }
00043 
00044 time_t mktimegm(struct tm *tm)
00045 {
00046     time_t t;
00047 
00048     int y = tm->tm_year + 1900, m = tm->tm_mon + 1, d = tm->tm_mday;
00049 
00050     if (m < 3) {
00051         m += 12;
00052         y--;
00053     }
00054 
00055     t = 86400 *
00056         (d + (153 * m - 457) / 5 + 365 * y + y / 4 - y / 100 + y / 400 - 719469);
00057 
00058     t += 3600 * tm->tm_hour + 60 * tm->tm_min + tm->tm_sec;
00059 
00060     return t;
00061 }
00062 
00063 #define ISLEAP(y) (((y) % 4 == 0) && (((y) % 100) != 0 || ((y) % 400) == 0))
00064 #define LEAPS_COUNT(y) ((y)/4 - (y)/100 + (y)/400)
00065 
00066 /* This is our own gmtime_r. It differs from its POSIX counterpart in a
00067    couple of places, though. */
00068 struct tm *brktimegm(time_t secs, struct tm *tm)
00069 {
00070     int days, y, ny, m;
00071     int md[] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
00072 
00073     days = secs / 86400;
00074     secs %= 86400;
00075     tm->tm_hour = secs / 3600;
00076     tm->tm_min = (secs % 3600) / 60;
00077     tm->tm_sec =  secs % 60;
00078 
00079     /* oh well, may be someone some day will invent a formula for this stuff */
00080     y = 1970; /* start "guessing" */
00081     while (days > 365) {
00082         ny = (y + days/366);
00083         days -= (ny - y) * 365 + LEAPS_COUNT(ny - 1) - LEAPS_COUNT(y - 1);
00084         y = ny;
00085     }
00086     if (days==365 && !ISLEAP(y)) { days=0; y++; }
00087     md[1] = ISLEAP(y)?29:28;
00088     for (m=0; days >= md[m]; m++)
00089          days -= md[m];
00090 
00091     tm->tm_year = y;  /* unlike gmtime_r we store complete year here */
00092     tm->tm_mon = m+1; /* unlike gmtime_r tm_mon is from 1 to 12 */
00093     tm->tm_mday = days+1;
00094 
00095     return tm;
00096 }
00097 
00098 /* get a positive number between n_min and n_max, for a maximum length
00099    of len_max. Return -1 if error. */
00100 static int date_get_num(const char **pp,
00101                         int n_min, int n_max, int len_max)
00102 {
00103     int i, val, c;
00104     const char *p;
00105 
00106     p = *pp;
00107     val = 0;
00108     for(i = 0; i < len_max; i++) {
00109         c = *p;
00110         if (!isdigit(c))
00111             break;
00112         val = (val * 10) + c - '0';
00113         p++;
00114     }
00115     /* no number read ? */
00116     if (p == *pp)
00117         return -1;
00118     if (val < n_min || val > n_max)
00119         return -1;
00120     *pp = p;
00121     return val;
00122 }
00123 
00124 /* small strptime for ffmpeg */
00125 const char *small_strptime(const char *p, const char *fmt,
00126                            struct tm *dt)
00127 {
00128     int c, val;
00129 
00130     for(;;) {
00131         c = *fmt++;
00132         if (c == '\0') {
00133             return p;
00134         } else if (c == '%') {
00135             c = *fmt++;
00136             switch(c) {
00137             case 'H':
00138                 val = date_get_num(&p, 0, 23, 2);
00139                 if (val == -1)
00140                     return NULL;
00141                 dt->tm_hour = val;
00142                 break;
00143             case 'M':
00144                 val = date_get_num(&p, 0, 59, 2);
00145                 if (val == -1)
00146                     return NULL;
00147                 dt->tm_min = val;
00148                 break;
00149             case 'S':
00150                 val = date_get_num(&p, 0, 59, 2);
00151                 if (val == -1)
00152                     return NULL;
00153                 dt->tm_sec = val;
00154                 break;
00155             case 'Y':
00156                 val = date_get_num(&p, 0, 9999, 4);
00157                 if (val == -1)
00158                     return NULL;
00159                 dt->tm_year = val - 1900;
00160                 break;
00161             case 'm':
00162                 val = date_get_num(&p, 1, 12, 2);
00163                 if (val == -1)
00164                     return NULL;
00165                 dt->tm_mon = val - 1;
00166                 break;
00167             case 'd':
00168                 val = date_get_num(&p, 1, 31, 2);
00169                 if (val == -1)
00170                     return NULL;
00171                 dt->tm_mday = val;
00172                 break;
00173             case '%':
00174                 goto match;
00175             default:
00176                 return NULL;
00177             }
00178         } else {
00179         match:
00180             if (c != *p)
00181                 return NULL;
00182             p++;
00183         }
00184     }
00185     return p;
00186 }
00187 

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