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 #include <time.h>
  40
  41 /**
  42  * Convert seconds to a time in the format h:mm:ss.
  43  *
  44  * This function is provided for any interface function which need to print a
  45  * time string in the format h:mm:ss
  46  * date.
  47  * \param secs  the date to be converted
  48  * \param psz_buffer should be a buffer at least MSTRTIME_MAX_SIZE characters
  49  * \return psz_buffer is returned so this can be used as printf parameter.
  50  */
  51 char *secstotimestr( char *psz_buffer, int32_t i_seconds )
  52 {
  53     if( unlikely(i_seconds < 0) )
  54     {
  55         secstotimestr( psz_buffer + 1, -i_seconds );
  56         *psz_buffer = '-';
  57         return psz_buffer;
  58     }
  59
  60     div_t d;
  61
  62     d = div( i_seconds, 60 );
  63     i_seconds = d.rem;
  64     d = div( d.quot, 60 );
  65
  66     if( d.quot )
  67         snprintf( psz_buffer, MSTRTIME_MAX_SIZE, "%u:%02u:%02u",
  68                  d.quot, d.rem, i_seconds );
  69     else
  70         snprintf( psz_buffer, MSTRTIME_MAX_SIZE, "%02u:%02u",
  71                   d.rem, i_seconds );
  72     return psz_buffer;
  73 }
  74
  75 /*
  76  * Date management (internal and external)
  77  */
  78
  79 /**
  80  * Initialize a date_t.
  81  *
  82  * \param date to initialize
  83  * \param divider (sample rate) numerator
  84  * \param divider (sample rate) denominator
  85  */
  86
  87 void date_Init( date_t *p_date, uint32_t i_divider_n, uint32_t i_divider_d )
  88 {
  89     p_date->date = 0;
  90     p_date->i_divider_num = i_divider_n;
  91     p_date->i_divider_den = i_divider_d;
  92     p_date->i_remainder = 0;
  93 }
  94
  95 /**
  96  * Change a date_t.
  97  *
  98  * \param date to change
  99  * \param divider (sample rate) numerator
 100  * \param divider (sample rate) denominator
 101  */
 102
 103 void date_Change( date_t *p_date, uint32_t i_divider_n, uint32_t i_divider_d )
 104 {
 105     /* change time scale of remainder */
 106     p_date->i_remainder = p_date->i_remainder * i_divider_n / p_date->i_divider_num;
 107     p_date->i_divider_num = i_divider_n;
 108     p_date->i_divider_den = i_divider_d;
 109 }
 110
 111 /**
 112  * Set the date value of a date_t.
 113  *
 114  * \param date to set
 115  * \param date value
 116  */
 117 void date_Set( date_t *p_date, mtime_t i_new_date )
 118 {
 119     p_date->date = i_new_date;
 120     p_date->i_remainder = 0;
 121 }
 122
 123 /**
 124  * Get the date of a date_t
 125  *
 126  * \param date to get
 127  * \return date value
 128  */
 129 mtime_t date_Get( const date_t *p_date )
 130 {
 131     return p_date->date;
 132 }
 133
 134 /**
 135  * Move forwards or backwards the date of a date_t.
 136  *
 137  * \param date to move
 138  * \param difference value
 139  */
 140 void date_Move( date_t *p_date, mtime_t i_difference )
 141 {
 142     p_date->date += i_difference;
 143 }
 144
 145 /**
 146  * Increment the date and return the result, taking into account
 147  * rounding errors.
 148  *
 149  * \param date to increment
 150  * \param incrementation in number of samples
 151  * \return date value
 152  */
 153 mtime_t date_Increment( date_t *p_date, uint32_t i_nb_samples )
 154 {
 155     assert( p_date->i_divider_num != 0 );
 156     mtime_t i_dividend = i_nb_samples * CLOCK_FREQ * p_date->i_divider_den;
 157     lldiv_t d = lldiv( i_dividend, p_date->i_divider_num );
 158
 159     p_date->date += d.quot;
 160     p_date->i_remainder += (int)d.rem;
 161
 162     if( p_date->i_remainder >= p_date->i_divider_num )
 163     {
 164         /* This is Bresenham algorithm. */
 165         assert( p_date->i_remainder < 2*p_date->i_divider_num);
 166         p_date->date += 1;
 167         p_date->i_remainder -= p_date->i_divider_num;
 168     }
 169
 170     return p_date->date;
 171 }
 172
 173 /**
 174  * Decrement the date and return the result, taking into account
 175  * rounding errors.
 176  *
 177  * \param date to decrement
 178  * \param decrementation in number of samples
 179  * \return date value
 180  */
 181 mtime_t date_Decrement( date_t *p_date, uint32_t i_nb_samples )
 182 {
 183     mtime_t i_dividend = (mtime_t)i_nb_samples * CLOCK_FREQ * p_date->i_divider_den;
 184     p_date->date -= i_dividend / p_date->i_divider_num;
 185     unsigned i_rem_adjust = i_dividend % p_date->i_divider_num;
 186
 187     if( p_date->i_remainder < i_rem_adjust )
 188     {
 189         /* This is Bresenham algorithm. */
 190         assert( p_date->i_remainder < p_date->i_divider_num);
 191         p_date->date -= 1;
 192         p_date->i_remainder += p_date->i_divider_num;
 193     }
 194
 195     p_date->i_remainder -= i_rem_adjust;
 196
 197     return p_date->date;
 198 }
 199
 200 /**
 201  * @return NTP 64-bits timestamp in host byte order.
 202  */
 203 uint64_t NTPtime64(void)
 204 {
 205     struct timespec ts;
 206
 207     timespec_get(&ts, TIME_UTC);
 208
 209     /* Convert nanoseconds to 32-bits fraction (232 picosecond units) */
 210     uint64_t t = (uint64_t)(ts.tv_nsec) << 32;
 211     t /= 1000000000;
 212
 213     /* The offset to Unix epoch is 70 years (incl. 17 leap ones). There were
 214      * no leap seconds during that period since they had not been invented yet.
 215      */
 216     t |= ((UINT64_C(70) * 365 + 17) * 24 * 60 * 60 + ts.tv_sec) << 32;
 217     return t;
 218 }