1 /*****************************************************************************
2 * mtime.c: high resolution time management functions
3 * Functions are prototyped in mtime.h.
4 *****************************************************************************
5 * Copyright (C) 1998-2004 VideoLAN
8 * Authors: Vincent Seguin <seguin@via.ecp.fr>
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.
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.
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 *****************************************************************************/
27 * see if using Linux real-time extensions is possible and profitable
30 /*****************************************************************************
32 *****************************************************************************/
33 #include <stdio.h> /* sprintf() */
37 #if defined( PTH_INIT_IN_PTH_H ) /* GNU Pth */
42 # include <unistd.h> /* select() */
45 #ifdef HAVE_KERNEL_OS_H
46 # include <kernel/OS.h>
49 #if defined( WIN32 ) || defined( UNDER_CE )
52 # include <sys/time.h>
55 #if defined(HAVE_NANOSLEEP) && !defined(HAVE_STRUCT_TIMESPEC)
63 #if defined(HAVE_NANOSLEEP) && !defined(HAVE_DECL_NANOSLEEP)
64 int nanosleep(struct timespec *, struct timespec *);
68 * Return a date in a readable format
70 * This function converts a mtime date into a string.
71 * psz_buffer should be a buffer long enough to store the formatted
73 * \param date to be converted
74 * \param psz_buffer should be a buffer at least MSTRTIME_MAX_SIZE characters
75 * \return psz_buffer is returned so this can be used as printf parameter.
77 char *mstrtime( char *psz_buffer, mtime_t date )
79 static mtime_t ll1000 = 1000, ll60 = 60, ll24 = 24;
81 snprintf( psz_buffer, MSTRTIME_MAX_SIZE, "%02d:%02d:%02d-%03d.%03d",
82 (int) (date / (ll1000 * ll1000 * ll60 * ll60) % ll24),
83 (int) (date / (ll1000 * ll1000 * ll60) % ll60),
84 (int) (date / (ll1000 * ll1000) % ll60),
85 (int) (date / ll1000 % ll1000),
86 (int) (date % ll1000) );
91 * Convert seconds to a time in the format h:mm:ss.
93 * This function is provided for any interface function which need to print a
94 * time string in the format h:mm:ss
96 * \param secs the date to be converted
97 * \param psz_buffer should be a buffer at least MSTRTIME_MAX_SIZE characters
98 * \return psz_buffer is returned so this can be used as printf parameter.
100 char *secstotimestr( char *psz_buffer, int i_seconds )
102 snprintf( psz_buffer, MSTRTIME_MAX_SIZE, "%d:%2.2d:%2.2d",
103 (int) (i_seconds / (60 *60)),
104 (int) ((i_seconds / 60) % 60),
105 (int) (i_seconds % 60) );
106 return( psz_buffer );
110 * Return high precision date
112 * Uses the gettimeofday() function when possible (1 MHz resolution) or the
113 * ftime() function (1 kHz resolution).
115 mtime_t mdate( void )
117 #if defined( HAVE_KERNEL_OS_H )
118 return( real_time_clock_usecs() );
120 #elif defined( WIN32 ) || defined( UNDER_CE )
121 /* We don't need the real date, just the value of a high precision timer */
122 static mtime_t freq = I64C(-1);
125 if( freq == I64C(-1) )
127 /* Extract from the Tcl source code:
128 * (http://www.cs.man.ac.uk/fellowsd-bin/TIP/7.html)
130 * Some hardware abstraction layers use the CPU clock
131 * in place of the real-time clock as a performance counter
132 * reference. This results in:
133 * - inconsistent results among the processors on
134 * multi-processor systems.
135 * - unpredictable changes in performance counter frequency
136 * on "gearshift" processors such as Transmeta and
138 * There seems to be no way to test whether the performance
139 * counter is reliable, but a useful heuristic is that
140 * if its frequency is 1.193182 MHz or 3.579545 MHz, it's
141 * derived from a colorburst crystal and is therefore
142 * the RTC rather than the TSC. If it's anything else, we
143 * presume that the performance counter is unreliable.
146 freq = ( QueryPerformanceFrequency( (LARGE_INTEGER *)&freq ) &&
147 (freq == I64C(1193182) || freq == I64C(3579545) ) )
153 /* Microsecond resolution */
154 QueryPerformanceCounter( (LARGE_INTEGER *)&usec_time );
155 return ( usec_time * 1000000 ) / freq;
159 /* Fallback on GetTickCount() which has a milisecond resolution
160 * (actually, best case is about 10 ms resolution)
161 * GetTickCount() only returns a DWORD thus will wrap after
162 * about 49.7 days so we try to detect the wrapping. */
164 static CRITICAL_SECTION date_lock;
165 static mtime_t i_previous_time = I64C(-1);
166 static int i_wrap_counts = -1;
168 if( i_wrap_counts == -1 )
171 i_previous_time = I64C(1000) * GetTickCount();
172 InitializeCriticalSection( &date_lock );
176 EnterCriticalSection( &date_lock );
177 usec_time = I64C(1000) *
178 (i_wrap_counts * I64C(0x100000000) + GetTickCount());
179 if( i_previous_time > usec_time )
181 /* Counter wrapped */
183 usec_time += I64C(0x100000000000);
185 i_previous_time = usec_time;
186 LeaveCriticalSection( &date_lock );
192 struct timeval tv_date;
194 /* gettimeofday() could return an error, and should be tested. However, the
195 * only possible error, according to 'man', is EFAULT, which can not happen
196 * here, since tv is a local variable. */
197 gettimeofday( &tv_date, NULL );
198 return( (mtime_t) tv_date.tv_sec * 1000000 + (mtime_t) tv_date.tv_usec );
206 * This function uses select() and an system date function to wake up at a
207 * precise date. It should be used for process synchronization. If current date
208 * is posterior to wished date, the function returns immediately.
209 * \param date The date to wake up at
211 void mwait( mtime_t date )
213 #if defined( HAVE_KERNEL_OS_H )
216 delay = date - real_time_clock_usecs();
223 #elif defined( WIN32 ) || defined( UNDER_CE )
224 mtime_t usec_time, delay;
227 delay = date - usec_time;
236 struct timeval tv_date;
237 mtime_t delay; /* delay in msec, signed to detect errors */
239 /* see mdate() about gettimeofday() possible errors */
240 gettimeofday( &tv_date, NULL );
242 /* calculate delay and check if current date is before wished date */
243 delay = date - (mtime_t) tv_date.tv_sec * 1000000
244 - (mtime_t) tv_date.tv_usec
247 /* Linux/i386 has a granularity of 10 ms. It's better to be in advance
248 * than to be late. */
249 if( delay <= 0 ) /* wished date is now or already passed */
254 # if defined( PTH_INIT_IN_PTH_H )
257 # elif defined( ST_INIT_IN_ST_H )
262 # if defined( HAVE_NANOSLEEP )
264 struct timespec ts_delay;
265 ts_delay.tv_sec = delay / 1000000;
266 ts_delay.tv_nsec = (delay % 1000000) * 1000;
268 nanosleep( &ts_delay, NULL );
272 tv_date.tv_sec = delay / 1000000;
273 tv_date.tv_usec = delay % 1000000;
274 /* see msleep() about select() errors */
275 select( 0, NULL, NULL, NULL, &tv_date );
284 * More precise sleep()
286 * Portable usleep() function.
287 * \param delay the amount of time to sleep
289 void msleep( mtime_t delay )
291 #if defined( HAVE_KERNEL_OS_H )
294 #elif defined( PTH_INIT_IN_PTH_H )
297 #elif defined( ST_INIT_IN_ST_H )
300 #elif defined( WIN32 ) || defined( UNDER_CE )
301 Sleep( (int) (delay / 1000) );
303 #elif defined( HAVE_NANOSLEEP )
304 struct timespec ts_delay;
306 ts_delay.tv_sec = delay / 1000000;
307 ts_delay.tv_nsec = (delay % 1000000) * 1000;
309 nanosleep( &ts_delay, NULL );
312 struct timeval tv_delay;
314 tv_delay.tv_sec = delay / 1000000;
315 tv_delay.tv_usec = delay % 1000000;
317 /* select() return value should be tested, since several possible errors
318 * can occur. However, they should only happen in very particular occasions
319 * (i.e. when a signal is sent to the thread, or when memory is full), and
321 select( 0, NULL, NULL, NULL, &tv_delay );
327 * Date management (internal and external)
331 * Initialize a date_t.
333 * \param date to initialize
334 * \param divider (sample rate) numerator
335 * \param divider (sample rate) denominator
338 void date_Init( date_t *p_date, uint32_t i_divider_n, uint32_t i_divider_d )
341 p_date->i_divider_num = i_divider_n;
342 p_date->i_divider_den = i_divider_d;
343 p_date->i_remainder = 0;
349 * \param date to change
350 * \param divider (sample rate) numerator
351 * \param divider (sample rate) denominator
354 void date_Change( date_t *p_date, uint32_t i_divider_n, uint32_t i_divider_d )
356 p_date->i_divider_num = i_divider_n;
357 p_date->i_divider_den = i_divider_d;
361 * Set the date value of a date_t.
366 void date_Set( date_t *p_date, mtime_t i_new_date )
368 p_date->date = i_new_date;
369 p_date->i_remainder = 0;
373 * Get the date of a date_t
378 mtime_t date_Get( const date_t *p_date )
384 * Move forwards or backwards the date of a date_t.
386 * \param date to move
387 * \param difference value
389 void date_Move( date_t *p_date, mtime_t i_difference )
391 p_date->date += i_difference;
395 * Increment the date and return the result, taking into account
398 * \param date to increment
399 * \param incrementation in number of samples
402 mtime_t date_Increment( date_t *p_date, uint32_t i_nb_samples )
404 mtime_t i_dividend = (mtime_t)i_nb_samples * 1000000;
405 p_date->date += i_dividend / p_date->i_divider_num * p_date->i_divider_den;
406 p_date->i_remainder += (int)(i_dividend % p_date->i_divider_num);
408 if( p_date->i_remainder >= p_date->i_divider_num )
410 /* This is Bresenham algorithm. */
411 p_date->date += p_date->i_divider_den;
412 p_date->i_remainder -= p_date->i_divider_num;