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/*
* tctimer.h -- simple timer code for transcode.
* (C) 2006-2010 - Francesco Romani <fromani -at- gmail -dot- com>
*
* This file is part of transcode, a video stream processing tool.
*
* transcode 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.
*
* transcode 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, see <http://www.gnu.org/licenses/>.
*/
#ifndef TCTIMER_H
#define TCTIMER_H
#include "config.h"
#include <stdint.h>
typedef union tctimestamp_ TCTimestamp;
union tctimestamp_ {
uint64_t u;
double d;
};
/*
* Quick Summary:
*
* At time of writing, {import,demultiplex}_x11 is the only
* piece of transcode that uses timers.
* I've chosen to factorize such code and put here on libtc
* in order to make it more visible and to promote reviews.
*
* This code may look overengineered, I'd like to make it generic
* in order to easily introduce further, platform-specific, timing
* support (i.e. Linux RTC). They aren't yet ready since the overall
* X11 source support is still on work. More will follow soon.
*
*/
/*
* Time unit used: microseconds (1e-6)
* It's EXPECTED that client code requires a timing resolution at least
* one order of magnitude LESS precise than internal resolution, I.e.
* milliseconds.
*/
/*
* tc_gettime:
* return the current time using the best avalaible time source.
*
* Parameters:
* None.
* Return Value:
* time units elapsed since EPOCH.
*/
uint64_t tc_gettime(void);
/*************************************************************************/
typedef struct tctimer_ TCTimer;
struct tctimer_ {
uint64_t last_time;
/* timestamp of last timer reading */
int (*fini)(TCTimer *timer);
uint64_t (*elapsed)(TCTimer *timer);
int (*sleep)(TCTimer *timer, uint64_t amount);
};
int tc_timer_init_soft(TCTimer *timer, uint16_t frequency);
/*
* tc_timer_fini:
* finalize given timer by freeing all resources acquired.
*
* Parameters:
* timer: timer to finalize.
* Return Value:
* 0 : succesfull.
* -1: error.
*/
#ifdef HAVE_GCC_ATTRIBUTES
__attribute__((unused))
#endif
static int tc_timer_fini(TCTimer *timer)
{
return timer->fini(timer);
}
/*
* tc_timer_elapsed:
* read timer status and get the amount of time units
* elapsed *SINCE LAST READ*.
* First read automagically delivers right results,
* so client code hasn't to worry about this.
*
* Parameters:
* timer: timer to read.
* Return Value:
* time units elapsed since last reading.
* Side Effects:
* Update internal timestamp.
*/
#ifdef HAVE_GCC_ATTRIBUTES
__attribute__((unused))
#endif
static uint64_t tc_timer_elapsed(TCTimer *timer)
{
return timer->elapsed(timer);
}
/*
* tc_timer_sleep:
* blocks caller (thread) for given amount of time units.
*
* *PLEASE NOTE*
* that this function CAN'T guarantee STRICT observancy of
* sleeping time. It is very likely that blocking time is
* different (usually greater) than wanted.
* Providing more guarantees involve deeper interaction with
* host OS that is out of the scope of this code, yet.
*
* Parameters:
* timer: timer to use.
* amount: (try to) block caller for this amount of time units.
* Return Value:
* 0: succesfully. Blocked for given amount of time units
* (see note above)
* -1: failed: an error has caused premature return.
*/
#ifdef HAVE_GCC_ATTRIBUTES
__attribute__((unused))
#endif
static int tc_timer_sleep(TCTimer *timer, uint64_t amount)
{
return timer->sleep(timer, amount);
}
#endif /* TCTIMER_H */
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