1 /*****************************************************************************
2 * mtime.c: high rezolution time management functions
3 * Functions are prototyped in mtime.h.
4 *****************************************************************************
5 * Copyright (C) 1998-2001 VideoLAN
6 * $Id: mtime.c,v 1.36 2003/06/05 11:52:19 gbazin Exp $
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
*);
67 /*****************************************************************************
68 * mstrtime: return a date in a readable format
69 *****************************************************************************
70 * This functions is provided for any interface function which need to print a
71 * date. psz_buffer should be a buffer long enough to store the formatted
73 *****************************************************************************/
74 char *mstrtime( char *psz_buffer
, mtime_t date
)
76 static mtime_t ll1000
= 1000, ll60
= 60, ll24
= 24;
78 sprintf( psz_buffer
, "%02d:%02d:%02d-%03d.%03d",
79 (int) (date
/ (ll1000
* ll1000
* ll60
* ll60
) % ll24
),
80 (int) (date
/ (ll1000
* ll1000
* ll60
) % ll60
),
81 (int) (date
/ (ll1000
* ll1000
) % ll60
),
82 (int) (date
/ ll1000
% ll1000
),
83 (int) (date
% ll1000
) );
87 /*****************************************************************************
88 * mdate: return high precision date
89 *****************************************************************************
90 * Uses the gettimeofday() function when possible (1 MHz resolution) or the
91 * ftime() function (1 kHz resolution).
92 *****************************************************************************/
95 #if defined( HAVE_KERNEL_OS_H )
96 return( real_time_clock_usecs() );
98 #elif defined( WIN32 ) || defined( UNDER_CE )
99 /* We don't need the real date, just the value of a high precision timer */
100 static mtime_t freq
= I64C(-1);
103 if( freq
== I64C(-1) )
105 /* Extract from the Tcl source code:
106 * (http://www.cs.man.ac.uk/fellowsd-bin/TIP/7.html)
108 * Some hardware abstraction layers use the CPU clock
109 * in place of the real-time clock as a performance counter
110 * reference. This results in:
111 * - inconsistent results among the processors on
112 * multi-processor systems.
113 * - unpredictable changes in performance counter frequency
114 * on "gearshift" processors such as Transmeta and
116 * There seems to be no way to test whether the performance
117 * counter is reliable, but a useful heuristic is that
118 * if its frequency is 1.193182 MHz or 3.579545 MHz, it's
119 * derived from a colorburst crystal and is therefore
120 * the RTC rather than the TSC. If it's anything else, we
121 * presume that the performance counter is unreliable.
124 freq
= ( QueryPerformanceFrequency( (LARGE_INTEGER
*)&freq
) &&
125 (freq
== I64C(1193182) || freq
== I64C(3579545) ) )
131 /* Microsecond resolution */
132 QueryPerformanceCounter( (LARGE_INTEGER
*)&usec_time
);
133 return ( usec_time
* 1000000 ) / freq
;
136 /* Milisecond resolution (actually, best case is about 10 ms resolution) */
137 return 1000 * GetTickCount();
140 struct timeval tv_date
;
142 /* gettimeofday() could return an error, and should be tested. However, the
143 * only possible error, according to 'man', is EFAULT, which can not happen
144 * here, since tv is a local variable. */
145 gettimeofday( &tv_date
, NULL
);
146 return( (mtime_t
) tv_date
.tv_sec
* 1000000 + (mtime_t
) tv_date
.tv_usec
);
151 /*****************************************************************************
152 * mwait: wait for a date
153 *****************************************************************************
154 * This function uses select() and an system date function to wake up at a
155 * precise date. It should be used for process synchronization. If current date
156 * is posterior to wished date, the function returns immediately.
157 *****************************************************************************/
158 void mwait( mtime_t date
)
160 #if defined( HAVE_KERNEL_OS_H )
163 delay
= date
- real_time_clock_usecs();
170 #elif defined( WIN32 ) || defined( UNDER_CE )
171 mtime_t usec_time
, delay
;
174 delay
= date
- usec_time
;
183 struct timeval tv_date
;
184 mtime_t delay
; /* delay in msec, signed to detect errors */
186 /* see mdate() about gettimeofday() possible errors */
187 gettimeofday( &tv_date
, NULL
);
189 /* calculate delay and check if current date is before wished date */
190 delay
= date
- (mtime_t
) tv_date
.tv_sec
* 1000000
191 - (mtime_t
) tv_date
.tv_usec
194 /* Linux/i386 has a granularity of 10 ms. It's better to be in advance
195 * than to be late. */
196 if( delay
<= 0 ) /* wished date is now or already passed */
201 # if defined( PTH_INIT_IN_PTH_H )
204 # elif defined( ST_INIT_IN_ST_H )
209 # if defined( HAVE_NANOSLEEP )
211 struct timespec ts_delay
;
212 ts_delay
.tv_sec
= delay
/ 1000000;
213 ts_delay
.tv_nsec
= (delay
% 1000000) * 1000;
215 nanosleep( &ts_delay
, NULL
);
219 tv_date
.tv_sec
= delay
/ 1000000;
220 tv_date
.tv_usec
= delay
% 1000000;
221 /* see msleep() about select() errors */
222 select( 0, NULL
, NULL
, NULL
, &tv_date
);
230 /*****************************************************************************
231 * msleep: more precise sleep()
232 *****************************************************************************
233 * Portable usleep() function.
234 *****************************************************************************/
235 void msleep( mtime_t delay
)
237 #if defined( HAVE_KERNEL_OS_H )
240 #elif defined( PTH_INIT_IN_PTH_H )
243 #elif defined( ST_INIT_IN_ST_H )
246 #elif defined( WIN32 ) || defined( UNDER_CE )
247 Sleep( (int) (delay
/ 1000) );
249 #elif defined( HAVE_NANOSLEEP )
250 struct timespec ts_delay
;
252 ts_delay
.tv_sec
= delay
/ 1000000;
253 ts_delay
.tv_nsec
= (delay
% 1000000) * 1000;
255 nanosleep( &ts_delay
, NULL
);
258 struct timeval tv_delay
;
260 tv_delay
.tv_sec
= delay
/ 1000000;
261 tv_delay
.tv_usec
= delay
% 1000000;
263 /* select() return value should be tested, since several possible errors
264 * can occur. However, they should only happen in very particular occasions
265 * (i.e. when a signal is sent to the thread, or when memory is full), and
267 select( 0, NULL
, NULL
, NULL
, &tv_delay
);