1 /*****************************************************************************
2 * mtime.c: high resolution time management functions
3 * Functions are prototyped in mtime.h.
4 *****************************************************************************
5 * Copyright (C) 1998-2004 the VideoLAN team
8 * Authors: Vincent Seguin <seguin@via.ecp.fr>
9 * RĂ©mi Denis-Courmont <rem$videolan,org>
11 * This program is free software; you can redistribute it and/or modify
12 * it under the terms of the GNU General Public License as published by
13 * the Free Software Foundation; either version 2 of the License, or
14 * (at your option) any later version.
16 * This program is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 * GNU General Public License for more details.
21 * You should have received a copy of the GNU General Public License
22 * along with this program; if not, write to the Free Software
23 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
24 *****************************************************************************/
26 /*****************************************************************************
28 *****************************************************************************/
29 #include <stdio.h> /* sprintf() */
30 #include <time.h> /* clock_gettime(), clock_nanosleep() */
31 #include <stdlib.h> /* ldiv() */
35 #if defined( PTH_INIT_IN_PTH_H ) /* GNU Pth */
40 # include <unistd.h> /* select() */
43 #ifdef HAVE_KERNEL_OS_H
44 # include <kernel/OS.h>
47 #if defined( WIN32 ) || defined( UNDER_CE )
50 # include <sys/time.h>
53 #if defined(HAVE_NANOSLEEP) && !defined(HAVE_STRUCT_TIMESPEC)
61 #if defined(HAVE_NANOSLEEP) && !defined(HAVE_DECL_NANOSLEEP)
62 int nanosleep(struct timespec *, struct timespec *);
66 * Return a date in a readable format
68 * This function converts a mtime date into a string.
69 * psz_buffer should be a buffer long enough to store the formatted
71 * \param date to be converted
72 * \param psz_buffer should be a buffer at least MSTRTIME_MAX_SIZE characters
73 * \return psz_buffer is returned so this can be used as printf parameter.
75 char *mstrtime( char *psz_buffer, mtime_t date )
77 static mtime_t ll1000 = 1000, ll60 = 60, ll24 = 24;
79 snprintf( psz_buffer, MSTRTIME_MAX_SIZE, "%02d:%02d:%02d-%03d.%03d",
80 (int) (date / (ll1000 * ll1000 * ll60 * ll60) % ll24),
81 (int) (date / (ll1000 * ll1000 * ll60) % ll60),
82 (int) (date / (ll1000 * ll1000) % ll60),
83 (int) (date / ll1000 % ll1000),
84 (int) (date % ll1000) );
89 * Convert seconds to a time in the format h:mm:ss.
91 * This function is provided for any interface function which need to print a
92 * time string in the format h:mm:ss
94 * \param secs the date to be converted
95 * \param psz_buffer should be a buffer at least MSTRTIME_MAX_SIZE characters
96 * \return psz_buffer is returned so this can be used as printf parameter.
98 char *secstotimestr( char *psz_buffer, int i_seconds )
100 snprintf( psz_buffer, MSTRTIME_MAX_SIZE, "%d:%2.2d:%2.2d",
101 (int) (i_seconds / (60 *60)),
102 (int) ((i_seconds / 60) % 60),
103 (int) (i_seconds % 60) );
104 return( psz_buffer );
109 * Return high precision date
111 * Uses the gettimeofday() function when possible (1 MHz resolution) or the
112 * ftime() function (1 kHz resolution).
114 mtime_t mdate( void )
116 #if defined( HAVE_KERNEL_OS_H )
117 return( real_time_clock_usecs() );
119 #elif defined( WIN32 ) || defined( UNDER_CE )
120 /* We don't need the real date, just the value of a high precision timer */
121 static mtime_t freq = I64C(-1);
124 if( freq == I64C(-1) )
126 /* Extract from the Tcl source code:
127 * (http://www.cs.man.ac.uk/fellowsd-bin/TIP/7.html)
129 * Some hardware abstraction layers use the CPU clock
130 * in place of the real-time clock as a performance counter
131 * reference. This results in:
132 * - inconsistent results among the processors on
133 * multi-processor systems.
134 * - unpredictable changes in performance counter frequency
135 * on "gearshift" processors such as Transmeta and
137 * There seems to be no way to test whether the performance
138 * counter is reliable, but a useful heuristic is that
139 * if its frequency is 1.193182 MHz or 3.579545 MHz, it's
140 * derived from a colorburst crystal and is therefore
141 * the RTC rather than the TSC. If it's anything else, we
142 * presume that the performance counter is unreliable.
145 freq = ( QueryPerformanceFrequency( (LARGE_INTEGER *)&freq ) &&
146 (freq == I64C(1193182) || freq == I64C(3579545) ) )
152 /* Microsecond resolution */
153 QueryPerformanceCounter( (LARGE_INTEGER *)&usec_time );
154 return ( usec_time * 1000000 ) / freq;
158 /* Fallback on GetTickCount() which has a milisecond resolution
159 * (actually, best case is about 10 ms resolution)
160 * GetTickCount() only returns a DWORD thus will wrap after
161 * about 49.7 days so we try to detect the wrapping. */
163 static CRITICAL_SECTION date_lock;
164 static mtime_t i_previous_time = I64C(-1);
165 static int i_wrap_counts = -1;
167 if( i_wrap_counts == -1 )
170 i_previous_time = I64C(1000) * GetTickCount();
171 InitializeCriticalSection( &date_lock );
175 EnterCriticalSection( &date_lock );
176 usec_time = I64C(1000) *
177 (i_wrap_counts * I64C(0x100000000) + GetTickCount());
178 if( i_previous_time > usec_time )
180 /* Counter wrapped */
182 usec_time += I64C(0x100000000000);
184 i_previous_time = usec_time;
185 LeaveCriticalSection( &date_lock );
190 #elif defined (HAVE_CLOCK_GETTIME)
193 # ifdef _POSIX_MONOTONIC_CLOCK
194 /* Try to use POSIX monotonic clock if available */
195 if( clock_gettime( CLOCK_MONOTONIC, &ts ) )
197 /* Run-time fallback to real-time clock (always available) */
198 (void)clock_gettime( CLOCK_REALTIME, &ts );
200 return (ts.tv_sec * 1000000) + (ts.tv_nsec / 1000);
202 struct timeval tv_date;
204 /* gettimeofday() cannot fail given &tv_date is a valid address */
205 (void)gettimeofday( &tv_date, NULL );
206 return( (mtime_t) tv_date.tv_sec * 1000000 + (mtime_t) tv_date.tv_usec );
213 * This function uses select() and an system date function to wake up at a
214 * precise date. It should be used for process synchronization. If current date
215 * is posterior to wished date, the function returns immediately.
216 * \param date The date to wake up at
218 void mwait( mtime_t date )
220 #if defined( HAVE_KERNEL_OS_H )
223 delay = date - real_time_clock_usecs();
230 #elif defined( WIN32 ) || defined( UNDER_CE )
231 mtime_t usec_time, delay;
234 delay = date - usec_time;
241 #elif defined (HAVE_CLOCK_GETTIME)
247 * Ideally, we'd use absolute time (TIMER_ABSTIME), instead of
248 * computing the time difference... but VLC mtime_t type seems to
249 * overflow way too quickly for this to work properly, or maybe it's a
250 * signedness problem (??).
256 d = ldiv( date, 1000000 );
258 ts.tv_nsec = d.rem * 1000;
260 # ifdef _POSIX_MONOTONIC_CLOCK
261 if( clock_nanosleep( CLOCK_MONOTONIC, 0 /*TIMER_ABSTIME*/, &ts, NULL ) )
263 (void)clock_nanosleep( CLOCK_REALTIME, 0, &ts, NULL );
266 struct timeval tv_date;
267 mtime_t delay; /* delay in msec, signed to detect errors */
269 /* see mdate() about gettimeofday() possible errors */
270 gettimeofday( &tv_date, NULL );
272 /* calculate delay and check if current date is before wished date */
273 delay = date - (mtime_t) tv_date.tv_sec * 1000000
274 - (mtime_t) tv_date.tv_usec
277 /* Linux/i386 has a granularity of 10 ms. It's better to be in advance
278 * than to be late. */
279 if( delay <= 0 ) /* wished date is now or already passed */
284 # if defined( PTH_INIT_IN_PTH_H )
287 # elif defined( ST_INIT_IN_ST_H )
292 # if defined( HAVE_NANOSLEEP )
294 struct timespec ts_delay;
295 ts_delay.tv_sec = delay / 1000000;
296 ts_delay.tv_nsec = (delay % 1000000) * 1000;
298 nanosleep( &ts_delay, NULL );
302 tv_date.tv_sec = delay / 1000000;
303 tv_date.tv_usec = delay % 1000000;
304 /* see msleep() about select() errors */
305 select( 0, NULL, NULL, NULL, &tv_date );
314 * More precise sleep()
316 * Portable usleep() function.
317 * \param delay the amount of time to sleep
319 void msleep( mtime_t delay )
321 #if defined( HAVE_KERNEL_OS_H )
324 #elif defined( PTH_INIT_IN_PTH_H )
327 #elif defined( ST_INIT_IN_ST_H )
330 #elif defined( WIN32 ) || defined( UNDER_CE )
331 Sleep( (int) (delay / 1000) );
333 #elif defined( HAVE_NANOSLEEP )
334 struct timespec ts_delay;
336 ts_delay.tv_sec = delay / 1000000;
337 ts_delay.tv_nsec = (delay % 1000000) * 1000;
339 nanosleep( &ts_delay, NULL );
342 struct timeval tv_delay;
344 tv_delay.tv_sec = delay / 1000000;
345 tv_delay.tv_usec = delay % 1000000;
347 /* select() return value should be tested, since several possible errors
348 * can occur. However, they should only happen in very particular occasions
349 * (i.e. when a signal is sent to the thread, or when memory is full), and
351 select( 0, NULL, NULL, NULL, &tv_delay );
357 * Date management (internal and external)
361 * Initialize a date_t.
363 * \param date to initialize
364 * \param divider (sample rate) numerator
365 * \param divider (sample rate) denominator
368 void date_Init( date_t *p_date, uint32_t i_divider_n, uint32_t i_divider_d )
371 p_date->i_divider_num = i_divider_n;
372 p_date->i_divider_den = i_divider_d;
373 p_date->i_remainder = 0;
379 * \param date to change
380 * \param divider (sample rate) numerator
381 * \param divider (sample rate) denominator
384 void date_Change( date_t *p_date, uint32_t i_divider_n, uint32_t i_divider_d )
386 p_date->i_divider_num = i_divider_n;
387 p_date->i_divider_den = i_divider_d;
391 * Set the date value of a date_t.
396 void date_Set( date_t *p_date, mtime_t i_new_date )
398 p_date->date = i_new_date;
399 p_date->i_remainder = 0;
403 * Get the date of a date_t
408 mtime_t date_Get( const date_t *p_date )
414 * Move forwards or backwards the date of a date_t.
416 * \param date to move
417 * \param difference value
419 void date_Move( date_t *p_date, mtime_t i_difference )
421 p_date->date += i_difference;
425 * Increment the date and return the result, taking into account
428 * \param date to increment
429 * \param incrementation in number of samples
432 mtime_t date_Increment( date_t *p_date, uint32_t i_nb_samples )
434 mtime_t i_dividend = (mtime_t)i_nb_samples * 1000000;
435 p_date->date += i_dividend / p_date->i_divider_num * p_date->i_divider_den;
436 p_date->i_remainder += (int)(i_dividend % p_date->i_divider_num);
438 if( p_date->i_remainder >= p_date->i_divider_num )
440 /* This is Bresenham algorithm. */
441 p_date->date += p_date->i_divider_den;
442 p_date->i_remainder -= p_date->i_divider_num;