/***************************************************************************** * mtime.c: high resolution time management functions * Functions are prototyped in mtime.h. ***************************************************************************** * Copyright (C) 1998-2004 VideoLAN * $Id$ * * Authors: Vincent Seguin <seguin@via.ecp.fr> * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA. *****************************************************************************/ /* * TODO: * see if using Linux real-time extensions is possible and profitable */ /***************************************************************************** * Preamble *****************************************************************************/ #include <stdio.h> /* sprintf() */ #include <vlc/vlc.h> #if defined( PTH_INIT_IN_PTH_H ) /* GNU Pth */ # include <pth.h> #endif #ifdef HAVE_UNISTD_H # include <unistd.h> /* select() */ #endif #ifdef HAVE_KERNEL_OS_H # include <kernel/OS.h> #endif #if defined( WIN32 ) || defined( UNDER_CE ) # include <windows.h> #else # include <sys/time.h> #endif #if defined(HAVE_NANOSLEEP) && !defined(HAVE_STRUCT_TIMESPEC) struct timespec { time_t tv_sec; int32_t tv_nsec; }; #endif #if defined(HAVE_NANOSLEEP) && !defined(HAVE_DECL_NANOSLEEP) int nanosleep(struct timespec *, struct timespec *); #endif /** * Return a date in a readable format * * This function converts a mtime date into a string. * psz_buffer should be a buffer long enough to store the formatted * date. * \param date to be converted * \param psz_buffer should be a buffer at least MSTRTIME_MAX_SIZE characters * \return psz_buffer is returned so this can be used as printf parameter. */ char *mstrtime( char *psz_buffer, mtime_t date ) { static mtime_t ll1000 = 1000, ll60 = 60, ll24 = 24; snprintf( psz_buffer, MSTRTIME_MAX_SIZE, "%02d:%02d:%02d-%03d.%03d", (int) (date / (ll1000 * ll1000 * ll60 * ll60) % ll24), (int) (date / (ll1000 * ll1000 * ll60) % ll60), (int) (date / (ll1000 * ll1000) % ll60), (int) (date / ll1000 % ll1000), (int) (date % ll1000) ); return( psz_buffer ); } /** * Convert seconds to a time in the format h:mm:ss. * * This function is provided for any interface function which need to print a * time string in the format h:mm:ss * date. * \param secs the date to be converted * \param psz_buffer should be a buffer at least MSTRTIME_MAX_SIZE characters * \return psz_buffer is returned so this can be used as printf parameter. */ char *secstotimestr( char *psz_buffer, int i_seconds ) { snprintf( psz_buffer, MSTRTIME_MAX_SIZE, "%d:%2.2d:%2.2d", (int) (i_seconds / (60 *60)), (int) ((i_seconds / 60) % 60), (int) (i_seconds % 60) ); return( psz_buffer ); } /** * Return high precision date * * Uses the gettimeofday() function when possible (1 MHz resolution) or the * ftime() function (1 kHz resolution). */ mtime_t mdate( void ) { #if defined( HAVE_KERNEL_OS_H ) return( real_time_clock_usecs() ); #elif defined( WIN32 ) || defined( UNDER_CE ) /* We don't need the real date, just the value of a high precision timer */ static mtime_t freq = I64C(-1); mtime_t usec_time; if( freq == I64C(-1) ) { /* Extract from the Tcl source code: * (http://www.cs.man.ac.uk/fellowsd-bin/TIP/7.html) * * Some hardware abstraction layers use the CPU clock * in place of the real-time clock as a performance counter * reference. This results in: * - inconsistent results among the processors on * multi-processor systems. * - unpredictable changes in performance counter frequency * on "gearshift" processors such as Transmeta and * SpeedStep. * There seems to be no way to test whether the performance * counter is reliable, but a useful heuristic is that * if its frequency is 1.193182 MHz or 3.579545 MHz, it's * derived from a colorburst crystal and is therefore * the RTC rather than the TSC. If it's anything else, we * presume that the performance counter is unreliable. */ freq = ( QueryPerformanceFrequency( (LARGE_INTEGER *)&freq ) && (freq == I64C(1193182) || freq == I64C(3579545) ) ) ? freq : 0; } if( freq != 0 ) { /* Microsecond resolution */ QueryPerformanceCounter( (LARGE_INTEGER *)&usec_time ); return ( usec_time * 1000000 ) / freq; } else { /* Fallback on GetTickCount() which has a milisecond resolution * (actually, best case is about 10 ms resolution) * GetTickCount() only returns a DWORD thus will wrap after * about 49.7 days so we try to detect the wrapping. */ static CRITICAL_SECTION date_lock; static mtime_t i_previous_time = I64C(-1); static int i_wrap_counts = -1; if( i_wrap_counts == -1 ) { /* Initialization */ i_previous_time = I64C(1000) * GetTickCount(); InitializeCriticalSection( &date_lock ); i_wrap_counts = 0; } EnterCriticalSection( &date_lock ); usec_time = I64C(1000) * (i_wrap_counts * I64C(0x100000000) + GetTickCount()); if( i_previous_time > usec_time ) { /* Counter wrapped */ i_wrap_counts++; usec_time += I64C(0x100000000000); } i_previous_time = usec_time; LeaveCriticalSection( &date_lock ); return usec_time; } #else 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 ); #endif } /** * Wait for a date * * 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. * \param date The date to wake up at */ void mwait( mtime_t date ) { #if defined( HAVE_KERNEL_OS_H ) mtime_t delay; delay = date - real_time_clock_usecs(); if( delay <= 0 ) { return; } snooze( delay ); #elif defined( WIN32 ) || defined( UNDER_CE ) mtime_t usec_time, delay; usec_time = mdate(); delay = date - usec_time; if( delay <= 0 ) { return; } msleep( delay ); #else struct timeval tv_date; mtime_t 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 - 10000; /* Linux/i386 has a granularity of 10 ms. It's better to be in advance * than to be late. */ if( delay <= 0 ) /* wished date is now or already passed */ { return; } # if defined( PTH_INIT_IN_PTH_H ) pth_usleep( delay ); # elif defined( ST_INIT_IN_ST_H ) st_usleep( delay ); # else # if defined( HAVE_NANOSLEEP ) { struct timespec ts_delay; ts_delay.tv_sec = delay / 1000000; ts_delay.tv_nsec = (delay % 1000000) * 1000; nanosleep( &ts_delay, NULL ); } # else tv_date.tv_sec = delay / 1000000; tv_date.tv_usec = delay % 1000000; /* see msleep() about select() errors */ select( 0, NULL, NULL, NULL, &tv_date ); # endif # endif #endif } /** * More precise sleep() * * Portable usleep() function. * \param delay the amount of time to sleep */ void msleep( mtime_t delay ) { #if defined( HAVE_KERNEL_OS_H ) snooze( delay ); #elif defined( PTH_INIT_IN_PTH_H ) pth_usleep( delay ); #elif defined( ST_INIT_IN_ST_H ) st_usleep( delay ); #elif defined( WIN32 ) || defined( UNDER_CE ) Sleep( (int) (delay / 1000) ); #elif defined( HAVE_NANOSLEEP ) struct timespec ts_delay; ts_delay.tv_sec = delay / 1000000; ts_delay.tv_nsec = (delay % 1000000) * 1000; nanosleep( &ts_delay, NULL ); #else 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 ignored. */ select( 0, NULL, NULL, NULL, &tv_delay ); #endif } /* * Date management (internal and external) */ /** * Initialize a date_t. * * \param date to initialize * \param divider (sample rate) numerator * \param divider (sample rate) denominator */ void date_Init( date_t *p_date, uint32_t i_divider_n, uint32_t i_divider_d ) { p_date->date = 0; p_date->i_divider_num = i_divider_n; p_date->i_divider_den = i_divider_d; p_date->i_remainder = 0; } /** * Change a date_t. * * \param date to change * \param divider (sample rate) numerator * \param divider (sample rate) denominator */ void date_Change( date_t *p_date, uint32_t i_divider_n, uint32_t i_divider_d ) { p_date->i_divider_num = i_divider_n; p_date->i_divider_den = i_divider_d; } /** * Set the date value of a date_t. * * \param date to set * \param date value */ void date_Set( date_t *p_date, mtime_t i_new_date ) { p_date->date = i_new_date; p_date->i_remainder = 0; } /** * Get the date of a date_t * * \param date to get * \return date value */ mtime_t date_Get( const date_t *p_date ) { return p_date->date; } /** * Move forwards or backwards the date of a date_t. * * \param date to move * \param difference value */ void date_Move( date_t *p_date, mtime_t i_difference ) { p_date->date += i_difference; } /** * Increment the date and return the result, taking into account * rounding errors. * * \param date to increment * \param incrementation in number of samples * \return date value */ mtime_t date_Increment( date_t *p_date, uint32_t i_nb_samples ) { mtime_t i_dividend = (mtime_t)i_nb_samples * 1000000; p_date->date += i_dividend / p_date->i_divider_num * p_date->i_divider_den; p_date->i_remainder += (int)(i_dividend % p_date->i_divider_num); if( p_date->i_remainder >= p_date->i_divider_num ) { /* This is Bresenham algorithm. */ p_date->date += p_date->i_divider_den; p_date->i_remainder -= p_date->i_divider_num; } return p_date->date; }