1 /*****************************************************************************
2 * mtime.c: high rezolution time management functions
3 * Functions are prototyped in mtime.h.
4 *****************************************************************************
5 * Copyright (C) 1998, 1999, 2000 VideoLAN
7 * Authors: Vincent Seguin <seguin@via.ecp.fr>
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation; either version 2 of the License, or
12 * (at your option) any later version.
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Public License for more details.
19 * You should have received a copy of the GNU General Public License
20 * along with this program; if not, write to the Free Software
21 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA.
22 *****************************************************************************/
26 * see if using Linux real-time extensions is possible and profitable
29 /*****************************************************************************
31 *****************************************************************************/
34 #include <stdio.h> /* sprintf() */
35 #include <unistd.h> /* select() */
38 #ifdef HAVE_KERNEL_OS_H
39 #include <kernel/OS.h>
46 /*****************************************************************************
47 * mstrtime: return a date in a readable format
48 *****************************************************************************
49 * This functions is provided for any interface function which need to print a
50 * date. psz_buffer should be a buffer long enough to store the formatted
52 *****************************************************************************/
53 char *mstrtime( char *psz_buffer, mtime_t date )
55 sprintf( psz_buffer, "%02d:%02d:%02d-%03d.%03d",
56 (int) (date / (1000LL * 1000LL * 60LL * 60LL) % 24LL),
57 (int) (date / (1000LL * 1000LL * 60LL) % 60LL),
58 (int) (date / (1000LL * 1000LL) % 60LL),
59 (int) (date / 1000LL % 1000LL),
60 (int) (date % 1000LL) );
64 /*****************************************************************************
65 * mdate: return high precision date (inline function)
66 *****************************************************************************
67 * Uses the gettimeofday() function when possible (1 MHz resolution) or the
68 * ftime() function (1 kHz resolution).
69 *****************************************************************************/
72 #ifdef HAVE_KERNEL_OS_H
73 return( real_time_clock_usecs() );
76 struct timeval tv_date;
78 /* gettimeofday() could return an error, and should be tested. However, the
79 * only possible error, according to 'man', is EFAULT, which can not happen
80 * here, since tv is a local variable. */
81 gettimeofday( &tv_date, NULL );
82 return( (mtime_t) tv_date.tv_sec * 1000000 + (mtime_t) tv_date.tv_usec );
87 /*****************************************************************************
88 * mwait: wait for a date (inline function)
89 *****************************************************************************
90 * This function uses select() and an system date function to wake up at a
91 * precise date. It should be used for process synchronization. If current date
92 * is posterior to wished date, the function returns immediately.
93 *****************************************************************************/
94 void mwait( mtime_t date )
96 #ifdef HAVE_KERNEL_OS_H
100 delay = date - real_time_clock_usecs();
109 struct timeval tv_date;
112 struct timeval tv_date, tv_delay;
115 mtime_t delay; /* delay in msec, signed to detect errors */
117 /* see mdate() about gettimeofday() possible errors */
118 gettimeofday( &tv_date, NULL );
120 /* calculate delay and check if current date is before wished date */
121 delay = date - (mtime_t) tv_date.tv_sec * 1000000 - (mtime_t) tv_date.tv_usec - 10000;
122 /* Linux/i386 has a granularity of 10 ms. It's better to be in advance
123 * than to be late. */
124 if( delay <= 0 ) /* wished date is now or already passed */
132 tv_delay.tv_sec = delay / 1000000;
133 tv_delay.tv_usec = delay % 1000000;
135 /* see msleep() about select() errors */
136 select( 0, NULL, NULL, NULL, &tv_delay );
139 #endif /* HAVE_KERNEL_OS_H */
142 /*****************************************************************************
143 * msleep: more precise sleep() (inline function) (ok ?)
144 *****************************************************************************
145 * Portable usleep() function.
146 *****************************************************************************/
147 void msleep( mtime_t delay )
149 #ifdef HAVE_KERNEL_OS_H
156 struct timeval tv_delay;
158 tv_delay.tv_sec = delay / 1000000;
159 tv_delay.tv_usec = delay % 1000000;
160 /* select() return value should be tested, since several possible errors
161 * can occur. However, they should only happen in very particular occasions
162 * (i.e. when a signal is sent to the thread, or when memory is full), and
163 * can be ingnored. */
164 select( 0, NULL, NULL, NULL, &tv_delay );
167 #endif /* HAVE_KERNEL_OS_H */