src/misc/mtime.c

   1 /*****************************************************************************
   2  * mtime.c: high rezolution time management functions
   3  * Functions are prototyped in mtime.h.
   4  *****************************************************************************
   5  * Copyright (C) 1998, 1999, 2000 VideoLAN
   6  * $Id: mtime.c,v 1.23 2001/06/14 20:21:04 sam Exp $
   7  *
   8  * Authors: Vincent Seguin <seguin@via.ecp.fr>
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License as published by
  12  * the Free Software Foundation; either version 2 of the License, or
  13  * (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  * GNU General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License
  21  * along with this program; if not, write to the Free Software
  22  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
  23  *****************************************************************************/
  24
  25 /*
  26  * TODO:
  27  *  see if using Linux real-time extensions is possible and profitable
  28  */
  29
  30 /*****************************************************************************
  31  * Preamble
  32  *****************************************************************************/
  33 #include "defs.h"
  34
  35 #include <stdio.h>                                              /* sprintf() */
  36
  37 #if defined( PTH_INIT_IN_PTH_H )                                  /* GNU Pth */
  38 #   include <pth.h>
  39 #endif
  40
  41 #ifdef HAVE_UNISTD_H
  42 #   include <unistd.h>                                           /* select() */
  43 #endif
  44
  45 #ifdef HAVE_KERNEL_OS_H
  46 #   include <kernel/OS.h>
  47 #endif
  48
  49 #if defined( WIN32 )
  50 #   include <windows.h>
  51 #else
  52 #   include <sys/time.h>
  53 #endif
  54
  55 #include "config.h"
  56 #include "common.h"
  57 #include "mtime.h"
  58
  59 #if defined( WIN32 )
  60 /*****************************************************************************
  61  * usleep: microsecond sleep for win32
  62  *****************************************************************************
  63  * This function uses performance counter if available, and Sleep() if not.
  64  *****************************************************************************/
  65 static __inline__ void usleep( unsigned int i_useconds )
  66 {
  67     s64 i_cur, i_freq;
  68     s64 i_now, i_then;
  69
  70     if( i_useconds < 1000
  71          && QueryPerformanceFrequency( (LARGE_INTEGER *) &i_freq ) )
  72     {
  73         QueryPerformanceCounter( (LARGE_INTEGER *) &i_cur );
  74
  75         i_now = ( i_cur * 1000 * 1000 / i_freq );
  76         i_then = i_now + i_useconds;
  77
  78         while( i_now < i_then )
  79         {
  80             QueryPerformanceCounter( (LARGE_INTEGER *) &i_cur );
  81             i_now = i_cur * 1000 * 1000 / i_freq;
  82         }
  83     }
  84     else
  85     {
  86         Sleep( (int) ((i_useconds + 500) / 1000) );
  87     }
  88 }
  89 #endif
  90
  91 /*****************************************************************************
  92  * mstrtime: return a date in a readable format
  93  *****************************************************************************
  94  * This functions is provided for any interface function which need to print a
  95  * date. psz_buffer should be a buffer long enough to store the formatted
  96  * date.
  97  *****************************************************************************/
  98 char *mstrtime( char *psz_buffer, mtime_t date )
  99 {
 100     sprintf( psz_buffer, "%02d:%02d:%02d-%03d.%03d",
 101              (int) (date / (I64C(1000) * I64C(1000) * I64C(60) * I64C(60)) % I64C(24)),
 102              (int) (date / (I64C(1000) * I64C(1000) * I64C(60)) % I64C(60)),
 103              (int) (date / (I64C(1000) * I64C(1000)) % I64C(60)),
 104              (int) (date / I64C(1000) % I64C(1000)),
 105              (int) (date % I64C(1000)) );
 106     return( psz_buffer );
 107 }
 108
 109 /*****************************************************************************
 110  * mdate: return high precision date (inline function)
 111  *****************************************************************************
 112  * Uses the gettimeofday() function when possible (1 MHz resolution) or the
 113  * ftime() function (1 kHz resolution).
 114  *****************************************************************************/
 115 mtime_t mdate( void )
 116 {
 117 #if defined( HAVE_KERNEL_OS_H )
 118     return( real_time_clock_usecs() );
 119
 120 #elif defined( WIN32 )
 121     /* We don't get the real date, just the value of a high precision timer.
 122      * this is because the usual time functions have at best only a milisecond
 123      * resolution */
 124     mtime_t freq, usec_time;
 125
 126     if( QueryPerformanceFrequency( (LARGE_INTEGER *)&freq ) )
 127     {
 128         /* Microsecond resolution */
 129         QueryPerformanceCounter( (LARGE_INTEGER *)&usec_time );
 130         return ( usec_time * 1000000 ) / freq;
 131     }
 132     else
 133     {
 134         /* Milisecond resolution */
 135         return 1000 * GetTickCount();
 136     }
 137
 138 #else
 139     struct timeval tv_date;
 140
 141     /* gettimeofday() could return an error, and should be tested. However, the
 142      * only possible error, according to 'man', is EFAULT, which can not happen
 143      * here, since tv is a local variable. */
 144     gettimeofday( &tv_date, NULL );
 145     return( (mtime_t) tv_date.tv_sec * 1000000 + (mtime_t) tv_date.tv_usec );
 146
 147 #endif
 148 }
 149
 150 /*****************************************************************************
 151  * mwait: wait for a date (inline function)
 152  *****************************************************************************
 153  * This function uses select() and an system date function to wake up at a
 154  * precise date. It should be used for process synchronization. If current date
 155  * is posterior to wished date, the function returns immediately.
 156  *****************************************************************************/
 157 void mwait( mtime_t date )
 158 {
 159 #if defined( HAVE_KERNEL_OS_H )
 160     mtime_t delay;
 161
 162     delay = date - real_time_clock_usecs();
 163     if( delay <= 0 )
 164     {
 165         return;
 166     }
 167     snooze( delay );
 168
 169 #elif defined( WIN32 )
 170     mtime_t usec_time, delay;
 171
 172     usec_time = mdate();
 173     delay = date - usec_time;
 174     if( delay <= 0 )
 175     {
 176         return;
 177     }
 178
 179     usleep( delay );
 180
 181 #else
 182
 183 #   ifdef HAVE_USLEEP
 184     struct timeval tv_date;
 185 #   else
 186     struct timeval tv_date, tv_delay;
 187 #   endif
 188     mtime_t        delay;          /* delay in msec, signed to detect errors */
 189
 190     /* see mdate() about gettimeofday() possible errors */
 191     gettimeofday( &tv_date, NULL );
 192
 193     /* calculate delay and check if current date is before wished date */
 194     delay = date - (mtime_t) tv_date.tv_sec * 1000000
 195                  - (mtime_t) tv_date.tv_usec
 196                  - 10000;
 197
 198     /* Linux/i386 has a granularity of 10 ms. It's better to be in advance
 199      * than to be late. */
 200     if( delay <= 0 )                 /* wished date is now or already passed */
 201     {
 202         return;
 203     }
 204
 205 #   if defined( PTH_INIT_IN_PTH_H )
 206     pth_usleep( delay );
 207
 208 #   elif defined( HAVE_USLEEP )
 209     usleep( delay );
 210
 211 #   else
 212     tv_delay.tv_sec = delay / 1000000;
 213     tv_delay.tv_usec = delay % 1000000;
 214     /* see msleep() about select() errors */
 215     select( 0, NULL, NULL, NULL, &tv_delay );
 216
 217 #   endif
 218
 219 #endif
 220 }
 221
 222 /*****************************************************************************
 223  * msleep: more precise sleep() (inline function)                        (ok ?)
 224  *****************************************************************************
 225  * Portable usleep() function.
 226  *****************************************************************************/
 227 void msleep( mtime_t delay )
 228 {
 229 #if defined( HAVE_KERNEL_OS_H )
 230     snooze( delay );
 231
 232 #elif defined( PTH_INIT_IN_PTH_H )
 233     struct timeval tv_delay;
 234     tv_delay.tv_sec = delay / 1000000;
 235     tv_delay.tv_usec = delay % 1000000;
 236     pth_select( 0, NULL, NULL, NULL, &tv_delay );
 237
 238 #elif defined( HAVE_USLEEP ) || defined( WIN32 )
 239     usleep( delay );
 240
 241 #else
 242     struct timeval tv_delay;
 243
 244     tv_delay.tv_sec = delay / 1000000;
 245     tv_delay.tv_usec = delay % 1000000;
 246     /* select() return value should be tested, since several possible errors
 247      * can occur. However, they should only happen in very particular occasions
 248      * (i.e. when a signal is sent to the thread, or when memory is full), and
 249      * can be ingnored. */
 250     select( 0, NULL, NULL, NULL, &tv_delay );
 251
 252 #endif
 253 }
 254