src/misc/mtime.c

   1 /*****************************************************************************
   2  * mtime.c: high resolution time management functions
   3  * Functions are prototyped in vlc_mtime.h.
   4  *****************************************************************************
   5  * Copyright (C) 1998-2007 VLC authors and VideoLAN
   6  * Copyright © 2006-2007 Rémi Denis-Courmont
   7  * $Id$
   8  *
   9  * Authors: Vincent Seguin <seguin@via.ecp.fr>
  10  *          Rémi Denis-Courmont <rem$videolan,org>
  11  *          Gisle Vanem
  12  *
  13  * This program is free software; you can redistribute it and/or modify it
  14  * under the terms of the GNU Lesser General Public License as published by
  15  * the Free Software Foundation; either version 2.1 of the License, or
  16  * (at your option) any later version.
  17  *
  18  * This program is distributed in the hope that it will be useful,
  19  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  20  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  21  * GNU Lesser General Public License for more details.
  22  *
  23  * You should have received a copy of the GNU Lesser General Public License
  24  * along with this program; if not, write to the Free Software Foundation,
  25  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  26  *****************************************************************************/
  27
  28 /*****************************************************************************
  29  * Preamble
  30  *****************************************************************************/
  31
  32 #ifdef HAVE_CONFIG_H
  33 # include "config.h"
  34 #endif
  35
  36 #include <vlc_common.h>
  37 #include <assert.h>
  38
  39 #ifdef HAVE_UNISTD_H
  40 # include <unistd.h>
  41 #endif
  42 #if !defined (_POSIX_TIMERS)
  43 # define _POSIX_TIMERS (-1)
  44 #endif
  45 #if (_POSIX_TIMERS > 0)
  46 # include <time.h> /* clock_gettime() */
  47 #else
  48 # include <sys/time.h>
  49 #endif
  50
  51 /**
  52  * Return a date in a readable format
  53  *
  54  * This function converts a mtime date into a string.
  55  * psz_buffer should be a buffer long enough to store the formatted
  56  * date.
  57  * \param date to be converted
  58  * \param psz_buffer should be a buffer at least MSTRTIME_MAX_SIZE characters
  59  * \return psz_buffer is returned so this can be used as printf parameter.
  60  */
  61 char *mstrtime( char *psz_buffer, mtime_t date )
  62 {
  63     static const mtime_t ll1000 = 1000, ll60 = 60, ll24 = 24;
  64
  65     snprintf( psz_buffer, MSTRTIME_MAX_SIZE, "%02d:%02d:%02d-%03d.%03d",
  66              (int) (date / (ll1000 * ll1000 * ll60 * ll60) % ll24),
  67              (int) (date / (ll1000 * ll1000 * ll60) % ll60),
  68              (int) (date / (ll1000 * ll1000) % ll60),
  69              (int) (date / ll1000 % ll1000),
  70              (int) (date % ll1000) );
  71     return( psz_buffer );
  72 }
  73
  74 /**
  75  * Convert seconds to a time in the format h:mm:ss.
  76  *
  77  * This function is provided for any interface function which need to print a
  78  * time string in the format h:mm:ss
  79  * date.
  80  * \param secs  the date to be converted
  81  * \param psz_buffer should be a buffer at least MSTRTIME_MAX_SIZE characters
  82  * \return psz_buffer is returned so this can be used as printf parameter.
  83  */
  84 char *secstotimestr( char *psz_buffer, int32_t i_seconds )
  85 {
  86     if( unlikely(i_seconds < 0) )
  87     {
  88         secstotimestr( psz_buffer + 1, -i_seconds );
  89         *psz_buffer = '-';
  90         return psz_buffer;
  91     }
  92
  93     div_t d;
  94
  95     d = div( i_seconds, 60 );
  96     i_seconds = d.rem;
  97     d = div( d.quot, 60 );
  98
  99     if( d.quot )
 100         snprintf( psz_buffer, MSTRTIME_MAX_SIZE, "%u:%02u:%02u",
 101                  d.quot, d.rem, i_seconds );
 102     else
 103         snprintf( psz_buffer, MSTRTIME_MAX_SIZE, "%02u:%02u",
 104                   d.rem, i_seconds );
 105     return psz_buffer;
 106 }
 107
 108 /*
 109  * Date management (internal and external)
 110  */
 111
 112 /**
 113  * Initialize a date_t.
 114  *
 115  * \param date to initialize
 116  * \param divider (sample rate) numerator
 117  * \param divider (sample rate) denominator
 118  */
 119
 120 void date_Init( date_t *p_date, uint32_t i_divider_n, uint32_t i_divider_d )
 121 {
 122     p_date->date = 0;
 123     p_date->i_divider_num = i_divider_n;
 124     p_date->i_divider_den = i_divider_d;
 125     p_date->i_remainder = 0;
 126 }
 127
 128 /**
 129  * Change a date_t.
 130  *
 131  * \param date to change
 132  * \param divider (sample rate) numerator
 133  * \param divider (sample rate) denominator
 134  */
 135
 136 void date_Change( date_t *p_date, uint32_t i_divider_n, uint32_t i_divider_d )
 137 {
 138     /* change time scale of remainder */
 139     p_date->i_remainder = p_date->i_remainder * i_divider_n / p_date->i_divider_num;
 140     p_date->i_divider_num = i_divider_n;
 141     p_date->i_divider_den = i_divider_d;
 142 }
 143
 144 /**
 145  * Set the date value of a date_t.
 146  *
 147  * \param date to set
 148  * \param date value
 149  */
 150 void date_Set( date_t *p_date, mtime_t i_new_date )
 151 {
 152     p_date->date = i_new_date;
 153     p_date->i_remainder = 0;
 154 }
 155
 156 /**
 157  * Get the date of a date_t
 158  *
 159  * \param date to get
 160  * \return date value
 161  */
 162 mtime_t date_Get( const date_t *p_date )
 163 {
 164     return p_date->date;
 165 }
 166
 167 /**
 168  * Move forwards or backwards the date of a date_t.
 169  *
 170  * \param date to move
 171  * \param difference value
 172  */
 173 void date_Move( date_t *p_date, mtime_t i_difference )
 174 {
 175     p_date->date += i_difference;
 176 }
 177
 178 /**
 179  * Increment the date and return the result, taking into account
 180  * rounding errors.
 181  *
 182  * \param date to increment
 183  * \param incrementation in number of samples
 184  * \return date value
 185  */
 186 mtime_t date_Increment( date_t *p_date, uint32_t i_nb_samples )
 187 {
 188     mtime_t i_dividend = i_nb_samples * CLOCK_FREQ * p_date->i_divider_den;
 189     lldiv_t d = lldiv( i_dividend, p_date->i_divider_num );
 190
 191     p_date->date += d.quot;
 192     p_date->i_remainder += (int)d.rem;
 193
 194     if( p_date->i_remainder >= p_date->i_divider_num )
 195     {
 196         /* This is Bresenham algorithm. */
 197         assert( p_date->i_remainder < 2*p_date->i_divider_num);
 198         p_date->date += 1;
 199         p_date->i_remainder -= p_date->i_divider_num;
 200     }
 201
 202     return p_date->date;
 203 }
 204
 205 /**
 206  * Decrement the date and return the result, taking into account
 207  * rounding errors.
 208  *
 209  * \param date to decrement
 210  * \param decrementation in number of samples
 211  * \return date value
 212  */
 213 mtime_t date_Decrement( date_t *p_date, uint32_t i_nb_samples )
 214 {
 215     mtime_t i_dividend = (mtime_t)i_nb_samples * 1000000 * p_date->i_divider_den;
 216     p_date->date -= i_dividend / p_date->i_divider_num;
 217     unsigned i_rem_adjust = i_dividend % p_date->i_divider_num;
 218
 219     if( p_date->i_remainder < i_rem_adjust )
 220     {
 221         /* This is Bresenham algorithm. */
 222         assert( p_date->i_remainder > -p_date->i_divider_num);
 223         p_date->date -= 1;
 224         p_date->i_remainder += p_date->i_divider_num;
 225     }
 226
 227     p_date->i_remainder -= i_rem_adjust;
 228
 229     return p_date->date;
 230 }
 231
 232 /**
 233  * @return NTP 64-bits timestamp in host byte order.
 234  */
 235 uint64_t NTPtime64 (void)
 236 {
 237 #if (_POSIX_TIMERS > 0)
 238     struct timespec ts;
 239
 240     clock_gettime (CLOCK_REALTIME, &ts);
 241 #else
 242     struct timeval tv;
 243     struct
 244     {
 245         uint32_t tv_sec;
 246         uint32_t tv_nsec;
 247     } ts;
 248
 249     gettimeofday (&tv, NULL);
 250     ts.tv_sec = tv.tv_sec;
 251     ts.tv_nsec = tv.tv_usec * 1000;
 252 #endif
 253
 254     /* Convert nanoseconds to 32-bits fraction (232 picosecond units) */
 255     uint64_t t = (uint64_t)(ts.tv_nsec) << 32;
 256     t /= 1000000000;
 257
 258
 259     /* There is 70 years (incl. 17 leap ones) offset to the Unix Epoch.
 260      * No leap seconds during that period since they were not invented yet.
 261      */
 262     assert (t < 0x100000000);
 263     t |= ((70LL * 365 + 17) * 24 * 60 * 60 + ts.tv_sec) << 32;
 264     return t;
 265 }
 266