ffmpeg/libavformat/cutils.c

58 lines
2.0 KiB
C

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