src/misc/mtime.c

   1 /*****************************************************************************
   2  * mtime.c: high resolution time management functions
   3  * Functions are prototyped in vlc_tick.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 #include <time.h>
  40 #include <stdlib.h>
  41
  42 /**
  43  * Convert seconds to a time in the format h:mm:ss.
  44  *
  45  * This function is provided for any interface function which need to print a
  46  * time string in the format h:mm:ss
  47  * date.
  48  * \param secs  the date to be converted
  49  * \param psz_buffer should be a buffer at least MSTRTIME_MAX_SIZE characters
  50  * \return psz_buffer is returned so this can be used as printf parameter.
  51  */
  52 char *secstotimestr( char *psz_buffer, int32_t i_seconds )
  53 {
  54     if( unlikely(i_seconds < 0) )
  55     {
  56         secstotimestr( psz_buffer + 1, -i_seconds );
  57         *psz_buffer = '-';
  58         return psz_buffer;
  59     }
  60
  61     div_t d;
  62
  63     d = div( i_seconds, 60 );
  64     i_seconds = d.rem;
  65     d = div( d.quot, 60 );
  66
  67     if( d.quot )
  68         snprintf( psz_buffer, MSTRTIME_MAX_SIZE, "%u:%02u:%02u",
  69                  d.quot, d.rem, i_seconds );
  70     else
  71         snprintf( psz_buffer, MSTRTIME_MAX_SIZE, "%02u:%02u",
  72                   d.rem, i_seconds );
  73     return psz_buffer;
  74 }
  75
  76 /*
  77  * Date management (internal and external)
  78  */
  79
  80 void date_Init( date_t *p_date, uint32_t i_divider_n, uint32_t i_divider_d )
  81 {
  82     p_date->date = VLC_TICK_INVALID;
  83     p_date->i_divider_num = i_divider_n;
  84     p_date->i_divider_den = i_divider_d;
  85     p_date->i_remainder = 0;
  86 }
  87
  88 void date_Change( date_t *p_date, uint32_t i_divider_n, uint32_t i_divider_d )
  89 {
  90     /* change time scale of remainder */
  91     p_date->i_remainder = p_date->i_remainder * i_divider_n / p_date->i_divider_num;
  92     p_date->i_divider_num = i_divider_n;
  93     p_date->i_divider_den = i_divider_d;
  94 }
  95
  96 vlc_tick_t date_Increment( date_t *p_date, uint32_t i_nb_samples )
  97 {
  98     if(unlikely(p_date->date == VLC_TICK_INVALID))
  99         return VLC_TICK_INVALID;
 100     assert( p_date->i_divider_num != 0 );
 101     vlc_tick_t i_dividend = i_nb_samples * CLOCK_FREQ * p_date->i_divider_den;
 102     lldiv_t d = lldiv( i_dividend, p_date->i_divider_num );
 103
 104     p_date->date += d.quot;
 105     p_date->i_remainder += (int)d.rem;
 106
 107     if( p_date->i_remainder >= p_date->i_divider_num )
 108     {
 109         /* This is Bresenham algorithm. */
 110         assert( p_date->i_remainder < 2*p_date->i_divider_num);
 111         p_date->date += 1;
 112         p_date->i_remainder -= p_date->i_divider_num;
 113     }
 114
 115     return p_date->date;
 116 }
 117
 118 vlc_tick_t date_Decrement( date_t *p_date, uint32_t i_nb_samples )
 119 {
 120     if(unlikely(p_date->date == VLC_TICK_INVALID))
 121         return VLC_TICK_INVALID;
 122     vlc_tick_t i_dividend = (vlc_tick_t)i_nb_samples * CLOCK_FREQ * p_date->i_divider_den;
 123     p_date->date -= i_dividend / p_date->i_divider_num;
 124     unsigned i_rem_adjust = i_dividend % p_date->i_divider_num;
 125
 126     if( p_date->i_remainder < i_rem_adjust )
 127     {
 128         /* This is Bresenham algorithm. */
 129         assert( p_date->i_remainder < p_date->i_divider_num);
 130         p_date->date -= 1;
 131         p_date->i_remainder += p_date->i_divider_num;
 132     }
 133
 134     p_date->i_remainder -= i_rem_adjust;
 135
 136     return p_date->date;
 137 }
 138
 139 /**
 140  * @return NTP 64-bits timestamp in host byte order.
 141  */
 142 uint64_t NTPtime64(void)
 143 {
 144     struct timespec ts;
 145
 146     timespec_get(&ts, TIME_UTC);
 147
 148     /* Convert nanoseconds to 32-bits fraction (232 picosecond units) */
 149     uint64_t t = (uint64_t)(ts.tv_nsec) << 32;
 150     t /= 1000000000;
 151
 152     /* The offset to Unix epoch is 70 years (incl. 17 leap ones). There were
 153      * no leap seconds during that period since they had not been invented yet.
 154      */
 155     t |= ((UINT64_C(70) * 365 + 17) * 24 * 60 * 60 + ts.tv_sec) << 32;
 156     return t;
 157 }
 158
 159 struct timespec timespec_from_vlc_tick (vlc_tick_t date)
 160 {
 161     lldiv_t d = lldiv (date, CLOCK_FREQ);
 162     struct timespec ts = { d.quot, NS_FROM_VLC_TICK( d.rem ) };
 163
 164     return ts;
 165 }