/******************************************************************************* * mtime.c: high rezolution time management functions * (c)1998 VideoLAN ******************************************************************************* * Functions are prototyped in mtime.h. ******************************************************************************* * to-do list: * see if using Linux real-time extensions is possible and profitable *******************************************************************************/ /******************************************************************************* * Preamble *******************************************************************************/ #include <stdio.h> #include <sys/time.h> #include "common.h" #include "mtime.h" /******************************************************************************* * mstrtime: return a date in a readable format ******************************************************************************* * This functions is provided for any interface function which need to print a * date. psz_buffer should be a buffer long enough to store the formatted * date. *******************************************************************************/ char *mstrtime( char *psz_buffer, mtime_t date ) { sprintf( psz_buffer, "%02d:%02d:%02d-%03d.%03d", (int) (date / (1000UL * 1000UL * 60UL * 60UL) % 24UL), (int) (date / (1000UL * 1000UL * 60UL) % 60UL), (int) (date / (1000UL * 1000UL) % 60UL), (int) (date / 1000UL % 1000UL), (int) (date % 1000UL) ); return( psz_buffer ); } /******************************************************************************* * mdate: return high precision date (inline function) ******************************************************************************* * Uses the gettimeofday() function when possible (1 MHz resolution) or the * ftime() function (1 kHz resolution). ******************************************************************************* * to-do list: ?? * implement the function when gettimeofday is not available * this function should be decalred as inline *******************************************************************************/ mtime_t mdate( void ) { struct timeval tv_date; /* gettimeofday() could return an error, and should be tested. However, the * only possible error, according to 'man', is EFAULT, which can not happen * here, since tv is a local variable. */ gettimeofday( &tv_date, NULL ); return( (mtime_t) tv_date.tv_sec * 1000000 + (mtime_t) tv_date.tv_usec ); } /******************************************************************************* * mwait: wait for a date (inline function) ******************************************************************************* * This function uses select() and an system date function to wake up at a * precise date. It should be used for process synchronization. If current date * is posterior to wished date, the function returns immediately. ******************************************************************************* * to-do list: * implement the function when gettimeofday is not available * optimize delay calculation * ?? declare as inline *******************************************************************************/ void mwait( mtime_t date ) { struct timeval tv_date, tv_delay; s64 delay; /* delay in msec, signed to detect errors */ /* see mdate() about gettimeofday() possible errors */ gettimeofday( &tv_date, NULL ); /* calculate delay and check if current date is before wished date */ delay = date - (mtime_t) tv_date.tv_sec * 1000000 - (mtime_t) tv_date.tv_usec; if( delay < 0 ) /* wished date is already passed */ { return; } tv_delay.tv_sec = delay / 1000000; tv_delay.tv_usec = delay % 1000000; /* see msleep() about select() errors */ select( 0, NULL, NULL, NULL, &tv_delay ); } /******************************************************************************* * msleep: more precise sleep() (inline function) (ok ?) ******************************************************************************* * This function uses select() in a classical way to implement a sleep() call * with a microsecond precision. * For synchronization purposes, mwait() should be prefered. ******************************************************************************* * ?? decalre as inline *******************************************************************************/ void msleep( mtime_t delay ) { struct timeval tv_delay; tv_delay.tv_sec = delay / 1000000; tv_delay.tv_usec = delay % 1000000; /* select() return value should be tested, since several possible errors * can occur. However, they should only happen in very particular occasions * (i.e. when a signal is sent to the thread, or when memory is full), and * can be ingnored. */ select( 0, NULL, NULL, NULL, &tv_delay ); }