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 the VideoLAN team
   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
  14  * it under the terms of the GNU General Public License as published by
  15  * the Free Software Foundation; either version 2 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 General Public License for more details.
  22  *
  23  * You should have received a copy of the GNU General Public License
  24  * along with this program; if not, write to the Free Software
  25  * Foundation, 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
  38 #include <time.h>                      /* clock_gettime(), clock_nanosleep() */
  39 #include <assert.h>
  40 #include <errno.h>
  41
  42 #ifdef HAVE_UNISTD_H
  43 #   include <unistd.h>                                           /* select() */
  44 #endif
  45
  46 #ifdef HAVE_KERNEL_OS_H
  47 #   include <kernel/OS.h>
  48 #endif
  49
  50 #if defined( WIN32 ) || defined( UNDER_CE )
  51 #   include <windows.h>
  52 #   include <mmsystem.h>
  53 #endif
  54
  55 #if defined(HAVE_SYS_TIME_H)
  56 #   include <sys/time.h>
  57 #endif
  58
  59 #if defined(__APPLE__) && !defined(__powerpc__) && !defined(__ppc__) && !defined(__ppc64__)
  60 #define USE_APPLE_MACH 1
  61 #   include <mach/mach.h>
  62 #   include <mach/mach_time.h>
  63 #endif
  64
  65 #if !defined(HAVE_STRUCT_TIMESPEC)
  66 struct timespec
  67 {
  68     time_t  tv_sec;
  69     int32_t tv_nsec;
  70 };
  71 #endif
  72
  73 #if defined(HAVE_NANOSLEEP) && !defined(HAVE_DECL_NANOSLEEP)
  74 int nanosleep(struct timespec *, struct timespec *);
  75 #endif
  76
  77 #if !defined (_POSIX_CLOCK_SELECTION)
  78 #  define _POSIX_CLOCK_SELECTION (-1)
  79 #endif
  80
  81 # if (_POSIX_CLOCK_SELECTION < 0)
  82 /*
  83  * We cannot use the monotonic clock if clock selection is not available,
  84  * as it would screw vlc_cond_timedwait() completely. Instead, we have to
  85  * stick to the realtime clock. Nevermind it screws everything up when ntpdate
  86  * warps the wall clock.
  87  */
  88 #  undef CLOCK_MONOTONIC
  89 #  define CLOCK_MONOTONIC CLOCK_REALTIME
  90 #elif !defined (HAVE_CLOCK_NANOSLEEP)
  91 /* Clock selection without clock in the first place, I don't think so. */
  92 #  error We have quite a situation here! Fix me if it ever happens.
  93 #endif
  94
  95 /**
  96  * Return a date in a readable format
  97  *
  98  * This function converts a mtime date into a string.
  99  * psz_buffer should be a buffer long enough to store the formatted
 100  * date.
 101  * \param date to be converted
 102  * \param psz_buffer should be a buffer at least MSTRTIME_MAX_SIZE characters
 103  * \return psz_buffer is returned so this can be used as printf parameter.
 104  */
 105 char *mstrtime( char *psz_buffer, mtime_t date )
 106 {
 107     static const mtime_t ll1000 = 1000, ll60 = 60, ll24 = 24;
 108
 109     snprintf( psz_buffer, MSTRTIME_MAX_SIZE, "%02d:%02d:%02d-%03d.%03d",
 110              (int) (date / (ll1000 * ll1000 * ll60 * ll60) % ll24),
 111              (int) (date / (ll1000 * ll1000 * ll60) % ll60),
 112              (int) (date / (ll1000 * ll1000) % ll60),
 113              (int) (date / ll1000 % ll1000),
 114              (int) (date % ll1000) );
 115     return( psz_buffer );
 116 }
 117
 118 /**
 119  * Convert seconds to a time in the format h:mm:ss.
 120  *
 121  * This function is provided for any interface function which need to print a
 122  * time string in the format h:mm:ss
 123  * date.
 124  * \param secs  the date to be converted
 125  * \param psz_buffer should be a buffer at least MSTRTIME_MAX_SIZE characters
 126  * \return psz_buffer is returned so this can be used as printf parameter.
 127  */
 128 char *secstotimestr( char *psz_buffer, int32_t i_seconds )
 129 {
 130     if( unlikely(i_seconds < 0) )
 131     {
 132         secstotimestr( psz_buffer + 1, -i_seconds );
 133         *psz_buffer = '-';
 134         return psz_buffer;
 135     }
 136
 137     div_t d;
 138
 139     d = div( i_seconds, 60 );
 140     i_seconds = d.rem;
 141     d = div( d.quot, 60 );
 142
 143     if( d.quot )
 144         snprintf( psz_buffer, MSTRTIME_MAX_SIZE, "%u:%02u:%02u",
 145                  d.quot, d.rem, i_seconds );
 146     else
 147         snprintf( psz_buffer, MSTRTIME_MAX_SIZE, "%02u:%02u",
 148                   d.rem, i_seconds );
 149     return psz_buffer;
 150 }
 151
 152 #if defined (HAVE_CLOCK_NANOSLEEP)
 153 static unsigned prec = 0;
 154
 155 static void mprec_once( void )
 156 {
 157     struct timespec ts;
 158     if( clock_getres( CLOCK_MONOTONIC, &ts ))
 159         clock_getres( CLOCK_REALTIME, &ts );
 160
 161     prec = ts.tv_nsec / 1000;
 162 }
 163 #endif
 164
 165 /**
 166  * Return a value that is no bigger than the clock precision
 167  * (possibly zero).
 168  */
 169 static inline unsigned mprec( void )
 170 {
 171 #if defined (HAVE_CLOCK_NANOSLEEP)
 172     static pthread_once_t once = PTHREAD_ONCE_INIT;
 173     pthread_once( &once, mprec_once );
 174     return prec;
 175 #else
 176     return 0;
 177 #endif
 178 }
 179
 180 #ifdef USE_APPLE_MACH
 181 static mach_timebase_info_data_t mtime_timebase_info;
 182 static pthread_once_t mtime_timebase_info_once = PTHREAD_ONCE_INIT;
 183 static void mtime_init_timebase(void)
 184 {
 185     mach_timebase_info(&mtime_timebase_info);
 186 }
 187 #endif
 188
 189 /**
 190  * Return high precision date
 191  *
 192  * Use a 1 MHz clock when possible, or 1 kHz
 193  *
 194  * Beware ! It doesn't reflect the actual date (since epoch), but can be the machine's uptime or anything (when monotonic clock is used)
 195  */
 196 mtime_t mdate( void )
 197 {
 198     mtime_t res;
 199
 200 #if defined (HAVE_CLOCK_NANOSLEEP)
 201     struct timespec ts;
 202
 203     /* Try to use POSIX monotonic clock if available */
 204     if( clock_gettime( CLOCK_MONOTONIC, &ts ) == EINVAL )
 205         /* Run-time fallback to real-time clock (always available) */
 206         (void)clock_gettime( CLOCK_REALTIME, &ts );
 207
 208     res = ((mtime_t)ts.tv_sec * (mtime_t)1000000)
 209            + (mtime_t)(ts.tv_nsec / 1000);
 210
 211 #elif defined( HAVE_KERNEL_OS_H )
 212     res = real_time_clock_usecs();
 213
 214 #elif defined( USE_APPLE_MACH )
 215     pthread_once(&mtime_timebase_info_once, mtime_init_timebase);
 216     uint64_t date = mach_absolute_time();
 217     mach_timebase_info_data_t tb = mtime_timebase_info;
 218
 219     /* tb.denom is uint32_t, switch to 64 bits to prevent overflow. */
 220     uint64_t denom = tb.denom;
 221
 222     /* Switch to microsecs */
 223     denom *= 1000LL;
 224
 225     /* Split the division to prevent overflow */
 226     lldiv_t d = lldiv (tb.numer, denom);
 227
 228     res = (d.quot * date) + ((d.rem * date) / denom);
 229
 230 #elif defined( WIN32 ) || defined( UNDER_CE )
 231     /* We don't need the real date, just the value of a high precision timer */
 232     LARGE_INTEGER counter, freq;
 233     if (!QueryPerformanceCounter (&counter)
 234      || !QueryPerformanceFrequency (&freq))
 235         abort();
 236
 237     /* Convert to from (1/freq) to microsecond resolution */
 238     /* We need to split the division to avoid 63-bits overflow */
 239     lldiv_t d = lldiv (counter.QuadPart, freq.QuadPart);
 240
 241     res = (d.quot * 1000000) + ((d.rem * 1000000) / freq.QuadPart);
 242
 243 #else
 244     struct timeval tv_date;
 245
 246     /* gettimeofday() cannot fail given &tv_date is a valid address */
 247     (void)gettimeofday( &tv_date, NULL );
 248     res = (mtime_t) tv_date.tv_sec * 1000000 + (mtime_t) tv_date.tv_usec;
 249 #endif
 250
 251     return res;
 252 }
 253
 254 #undef mwait
 255 /**
 256  * Wait for a date
 257  *
 258  * This function uses select() and an system date function to wake up at a
 259  * precise date. It should be used for process synchronization. If current date
 260  * is posterior to wished date, the function returns immediately.
 261  * \param date The date to wake up at
 262  */
 263 void mwait( mtime_t date )
 264 {
 265     /* If the deadline is already elapsed, or within the clock precision,
 266      * do not even bother the system timer. */
 267     date -= mprec();
 268
 269 #if defined (HAVE_CLOCK_NANOSLEEP)
 270     lldiv_t d = lldiv( date, 1000000 );
 271     struct timespec ts = { d.quot, d.rem * 1000 };
 272
 273     int val;
 274     while( ( val = clock_nanosleep( CLOCK_MONOTONIC, TIMER_ABSTIME, &ts,
 275                                     NULL ) ) == EINTR );
 276     if( val == EINVAL )
 277     {
 278         ts.tv_sec = d.quot; ts.tv_nsec = d.rem * 1000;
 279         while( clock_nanosleep( CLOCK_REALTIME, 0, &ts, NULL ) == EINTR );
 280     }
 281
 282 #elif defined (WIN32)
 283     mtime_t i_total;
 284
 285     while( (i_total = (date - mdate())) > 0 )
 286     {
 287         const mtime_t i_sleep = i_total / 1000;
 288         DWORD i_delay = (i_sleep > 0x7fffffff) ? 0x7fffffff : i_sleep;
 289         vlc_testcancel();
 290         SleepEx( i_delay, TRUE );
 291     }
 292     vlc_testcancel();
 293
 294 #else
 295     mtime_t delay = date - mdate();
 296     if( delay > 0 )
 297         msleep( delay );
 298
 299 #endif
 300 }
 301
 302
 303 #include "libvlc.h" /* vlc_backtrace() */
 304 #undef msleep
 305
 306 /**
 307  * Portable usleep(). Cancellation point.
 308  *
 309  * \param delay the amount of time to sleep
 310  */
 311 void msleep( mtime_t delay )
 312 {
 313 #if defined( HAVE_CLOCK_NANOSLEEP )
 314     lldiv_t d = lldiv( delay, 1000000 );
 315     struct timespec ts = { d.quot, d.rem * 1000 };
 316
 317     int val;
 318     while( ( val = clock_nanosleep( CLOCK_MONOTONIC, 0, &ts, &ts ) ) == EINTR );
 319     if( val == EINVAL )
 320     {
 321         ts.tv_sec = d.quot; ts.tv_nsec = d.rem * 1000;
 322         while( clock_nanosleep( CLOCK_REALTIME, 0, &ts, &ts ) == EINTR );
 323     }
 324
 325 #elif defined( HAVE_KERNEL_OS_H )
 326     snooze( delay );
 327
 328 #elif defined( WIN32 ) || defined( UNDER_CE )
 329     mwait (mdate () + delay);
 330
 331 #elif defined( HAVE_NANOSLEEP )
 332     struct timespec ts_delay;
 333
 334     ts_delay.tv_sec = delay / 1000000;
 335     ts_delay.tv_nsec = (delay % 1000000) * 1000;
 336
 337     while( nanosleep( &ts_delay, &ts_delay ) && ( errno == EINTR ) );
 338
 339 #elif defined (USE_APPLE_MACH)
 340     /* The version that should be used, if it was cancelable */
 341     pthread_once(&mtime_timebase_info_once, mtime_init_timebase);
 342     uint64_t mach_time = delay * 1000 * mtime_timebase_info.denom / mtime_timebase_info.numer;
 343     mach_wait_until(mach_time + mach_absolute_time());
 344
 345 #else
 346     struct timeval tv_delay;
 347
 348     tv_delay.tv_sec = delay / 1000000;
 349     tv_delay.tv_usec = delay % 1000000;
 350
 351     /* If a signal is caught, you are screwed. Update your OS to nanosleep()
 352      * or clock_nanosleep() if this is an issue. */
 353     select( 0, NULL, NULL, NULL, &tv_delay );
 354 #endif
 355 }
 356
 357 /*
 358  * Date management (internal and external)
 359  */
 360
 361 /**
 362  * Initialize a date_t.
 363  *
 364  * \param date to initialize
 365  * \param divider (sample rate) numerator
 366  * \param divider (sample rate) denominator
 367  */
 368
 369 void date_Init( date_t *p_date, uint32_t i_divider_n, uint32_t i_divider_d )
 370 {
 371     p_date->date = 0;
 372     p_date->i_divider_num = i_divider_n;
 373     p_date->i_divider_den = i_divider_d;
 374     p_date->i_remainder = 0;
 375 }
 376
 377 /**
 378  * Change a date_t.
 379  *
 380  * \param date to change
 381  * \param divider (sample rate) numerator
 382  * \param divider (sample rate) denominator
 383  */
 384
 385 void date_Change( date_t *p_date, uint32_t i_divider_n, uint32_t i_divider_d )
 386 {
 387     /* change time scale of remainder */
 388     p_date->i_remainder = p_date->i_remainder * i_divider_n / p_date->i_divider_num;
 389     p_date->i_divider_num = i_divider_n;
 390     p_date->i_divider_den = i_divider_d;
 391 }
 392
 393 /**
 394  * Set the date value of a date_t.
 395  *
 396  * \param date to set
 397  * \param date value
 398  */
 399 void date_Set( date_t *p_date, mtime_t i_new_date )
 400 {
 401     p_date->date = i_new_date;
 402     p_date->i_remainder = 0;
 403 }
 404
 405 /**
 406  * Get the date of a date_t
 407  *
 408  * \param date to get
 409  * \return date value
 410  */
 411 mtime_t date_Get( const date_t *p_date )
 412 {
 413     return p_date->date;
 414 }
 415
 416 /**
 417  * Move forwards or backwards the date of a date_t.
 418  *
 419  * \param date to move
 420  * \param difference value
 421  */
 422 void date_Move( date_t *p_date, mtime_t i_difference )
 423 {
 424     p_date->date += i_difference;
 425 }
 426
 427 /**
 428  * Increment the date and return the result, taking into account
 429  * rounding errors.
 430  *
 431  * \param date to increment
 432  * \param incrementation in number of samples
 433  * \return date value
 434  */
 435 mtime_t date_Increment( date_t *p_date, uint32_t i_nb_samples )
 436 {
 437     mtime_t i_dividend = (mtime_t)i_nb_samples * 1000000 * p_date->i_divider_den;
 438     p_date->date += i_dividend / p_date->i_divider_num;
 439     p_date->i_remainder += (int)(i_dividend % p_date->i_divider_num);
 440
 441     if( p_date->i_remainder >= p_date->i_divider_num )
 442     {
 443         /* This is Bresenham algorithm. */
 444         assert( p_date->i_remainder < 2*p_date->i_divider_num);
 445         p_date->date += 1;
 446         p_date->i_remainder -= p_date->i_divider_num;
 447     }
 448
 449     return p_date->date;
 450 }
 451
 452 /**
 453  * Decrement the date and return the result, taking into account
 454  * rounding errors.
 455  *
 456  * \param date to decrement
 457  * \param decrementation in number of samples
 458  * \return date value
 459  */
 460 mtime_t date_Decrement( date_t *p_date, uint32_t i_nb_samples )
 461 {
 462     mtime_t i_dividend = (mtime_t)i_nb_samples * 1000000 * p_date->i_divider_den;
 463     p_date->date -= i_dividend / p_date->i_divider_num;
 464     unsigned i_rem_adjust = i_dividend % p_date->i_divider_num;
 465
 466     if( p_date->i_remainder < i_rem_adjust )
 467     {
 468         /* This is Bresenham algorithm. */
 469         assert( p_date->i_remainder > -p_date->i_divider_num);
 470         p_date->date -= 1;
 471         p_date->i_remainder += p_date->i_divider_num;
 472     }
 473
 474     p_date->i_remainder -= i_rem_adjust;
 475
 476     return p_date->date;
 477 }
 478
 479 #ifndef HAVE_GETTIMEOFDAY
 480
 481 #ifdef WIN32
 482
 483 /*
 484  * Number of micro-seconds between the beginning of the Windows epoch
 485  * (Jan. 1, 1601) and the Unix epoch (Jan. 1, 1970).
 486  *
 487  * This assumes all Win32 compilers have 64-bit support.
 488  */
 489 #if defined(_MSC_VER) || defined(_MSC_EXTENSIONS) || defined(__WATCOMC__)
 490 #   define DELTA_EPOCH_IN_USEC  11644473600000000Ui64
 491 #else
 492 #   define DELTA_EPOCH_IN_USEC  11644473600000000ULL
 493 #endif
 494
 495 static uint64_t filetime_to_unix_epoch (const FILETIME *ft)
 496 {
 497     uint64_t res = (uint64_t) ft->dwHighDateTime << 32;
 498
 499     res |= ft->dwLowDateTime;
 500     res /= 10;                   /* from 100 nano-sec periods to usec */
 501     res -= DELTA_EPOCH_IN_USEC;  /* from Win epoch to Unix epoch */
 502     return (res);
 503 }
 504
 505 static int gettimeofday (struct timeval *tv, void *tz )
 506 {
 507     FILETIME  ft;
 508     uint64_t tim;
 509
 510     if (!tv) {
 511         return VLC_EGENERIC;
 512     }
 513     GetSystemTimeAsFileTime (&ft);
 514     tim = filetime_to_unix_epoch (&ft);
 515     tv->tv_sec  = (long) (tim / 1000000L);
 516     tv->tv_usec = (long) (tim % 1000000L);
 517     return (0);
 518 }
 519
 520 #endif
 521
 522 #endif
 523
 524 /**
 525  * @return NTP 64-bits timestamp in host byte order.
 526  */
 527 uint64_t NTPtime64 (void)
 528 {
 529     struct timespec ts;
 530 #if defined (CLOCK_REALTIME)
 531     clock_gettime (CLOCK_REALTIME, &ts);
 532 #else
 533     {
 534         struct timeval tv;
 535         gettimeofday (&tv, NULL);
 536         ts.tv_sec = tv.tv_sec;
 537         ts.tv_nsec = tv.tv_usec * 1000;
 538     }
 539 #endif
 540
 541     /* Convert nanoseconds to 32-bits fraction (232 picosecond units) */
 542     uint64_t t = (uint64_t)(ts.tv_nsec) << 32;
 543     t /= 1000000000;
 544
 545
 546     /* There is 70 years (incl. 17 leap ones) offset to the Unix Epoch.
 547      * No leap seconds during that period since they were not invented yet.
 548      */
 549     assert (t < 0x100000000);
 550     t |= ((70LL * 365 + 17) * 24 * 60 * 60 + ts.tv_sec) << 32;
 551     return t;
 552 }
 553