1 /*****************************************************************************
2 * mtime.c: high rezolution time management functions
3 * Functions are prototyped in mtime.h.
4 *****************************************************************************
5 * Copyright (C) 1998, 1999, 2000 VideoLAN
6 * $Id: mtime.c,v 1.16 2001/03/21 13:42:34 sam 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 *****************************************************************************/
35 #include <stdio.h> /* sprintf() */
36 #include <unistd.h> /* select() */
39 #ifdef HAVE_KERNEL_OS_H
40 #include <kernel/OS.h>
47 /*****************************************************************************
48 * mstrtime: return a date in a readable format
49 *****************************************************************************
50 * This functions is provided for any interface function which need to print a
51 * date. psz_buffer should be a buffer long enough to store the formatted
53 *****************************************************************************/
54 char *mstrtime( char *psz_buffer, mtime_t date )
56 sprintf( psz_buffer, "%02d:%02d:%02d-%03d.%03d",
57 (int) (date / (1000LL * 1000LL * 60LL * 60LL) % 24LL),
58 (int) (date / (1000LL * 1000LL * 60LL) % 60LL),
59 (int) (date / (1000LL * 1000LL) % 60LL),
60 (int) (date / 1000LL % 1000LL),
61 (int) (date % 1000LL) );
65 /*****************************************************************************
66 * mdate: return high precision date (inline function)
67 *****************************************************************************
68 * Uses the gettimeofday() function when possible (1 MHz resolution) or the
69 * ftime() function (1 kHz resolution).
70 *****************************************************************************/
73 #ifdef HAVE_KERNEL_OS_H
74 return( real_time_clock_usecs() );
77 struct timeval tv_date;
79 /* gettimeofday() could return an error, and should be tested. However, the
80 * only possible error, according to 'man', is EFAULT, which can not happen
81 * here, since tv is a local variable. */
82 gettimeofday( &tv_date, NULL );
83 return( (mtime_t) tv_date.tv_sec * 1000000 + (mtime_t) tv_date.tv_usec );
88 /*****************************************************************************
89 * mwait: wait for a date (inline function)
90 *****************************************************************************
91 * This function uses select() and an system date function to wake up at a
92 * precise date. It should be used for process synchronization. If current date
93 * is posterior to wished date, the function returns immediately.
94 *****************************************************************************/
95 void mwait( mtime_t date )
97 #ifdef HAVE_KERNEL_OS_H
101 delay = date - real_time_clock_usecs();
110 struct timeval tv_date;
113 struct timeval tv_date, tv_delay;
116 mtime_t delay; /* delay in msec, signed to detect errors */
118 /* see mdate() about gettimeofday() possible errors */
119 gettimeofday( &tv_date, NULL );
121 /* calculate delay and check if current date is before wished date */
122 delay = date - (mtime_t) tv_date.tv_sec * 1000000 - (mtime_t) tv_date.tv_usec - 10000;
123 /* Linux/i386 has a granularity of 10 ms. It's better to be in advance
124 * than to be late. */
125 if( delay <= 0 ) /* wished date is now or already passed */
133 tv_delay.tv_sec = delay / 1000000;
134 tv_delay.tv_usec = delay % 1000000;
136 /* see msleep() about select() errors */
137 select( 0, NULL, NULL, NULL, &tv_delay );
140 #endif /* HAVE_KERNEL_OS_H */
143 /*****************************************************************************
144 * msleep: more precise sleep() (inline function) (ok ?)
145 *****************************************************************************
146 * Portable usleep() function.
147 *****************************************************************************/
148 void msleep( mtime_t delay )
150 #ifdef HAVE_KERNEL_OS_H
157 struct timeval tv_delay;
159 tv_delay.tv_sec = delay / 1000000;
160 tv_delay.tv_usec = delay % 1000000;
161 /* select() return value should be tested, since several possible errors
162 * can occur. However, they should only happen in very particular occasions
163 * (i.e. when a signal is sent to the thread, or when memory is full), and
164 * can be ingnored. */
165 select( 0, NULL, NULL, NULL, &tv_delay );
168 #endif /* HAVE_KERNEL_OS_H */