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155 lines
4.0 KiB
155 lines
4.0 KiB
/*
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* tctimer.h -- simple timer code for transcode.
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* (C) 2006-2010 - Francesco Romani <fromani -at- gmail -dot- com>
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*
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* This file is part of transcode, a video stream processing tool.
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*
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* transcode is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* transcode is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef TCTIMER_H
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#define TCTIMER_H
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#include "config.h"
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#include <stdint.h>
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typedef union tctimestamp_ TCTimestamp;
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union tctimestamp_ {
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uint64_t u;
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double d;
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};
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/*
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* Quick Summary:
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*
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* At time of writing, {import,demultiplex}_x11 is the only
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* piece of transcode that uses timers.
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* I've chosen to factorize such code and put here on libtc
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* in order to make it more visible and to promote reviews.
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*
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* This code may look overengineered, I'd like to make it generic
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* in order to easily introduce further, platform-specific, timing
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* support (i.e. Linux RTC). They aren't yet ready since the overall
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* X11 source support is still on work. More will follow soon.
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*
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*/
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/*
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* Time unit used: microseconds (1e-6)
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* It's EXPECTED that client code requires a timing resolution at least
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* one order of magnitude LESS precise than internal resolution, I.e.
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* milliseconds.
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*/
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/*
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* tc_gettime:
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* return the current time using the best avalaible time source.
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*
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* Parameters:
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* None.
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* Return Value:
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* time units elapsed since EPOCH.
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*/
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uint64_t tc_gettime(void);
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/*************************************************************************/
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typedef struct tctimer_ TCTimer;
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struct tctimer_ {
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uint64_t last_time;
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/* timestamp of last timer reading */
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int (*fini)(TCTimer *timer);
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uint64_t (*elapsed)(TCTimer *timer);
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int (*sleep)(TCTimer *timer, uint64_t amount);
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};
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int tc_timer_init_soft(TCTimer *timer, uint16_t frequency);
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/*
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* tc_timer_fini:
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* finalize given timer by freeing all resources acquired.
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*
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* Parameters:
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* timer: timer to finalize.
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* Return Value:
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* 0 : succesfull.
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* -1: error.
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*/
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#ifdef HAVE_GCC_ATTRIBUTES
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__attribute__((unused))
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#endif
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static int tc_timer_fini(TCTimer *timer)
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{
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return timer->fini(timer);
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}
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/*
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* tc_timer_elapsed:
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* read timer status and get the amount of time units
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* elapsed *SINCE LAST READ*.
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* First read automagically delivers right results,
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* so client code hasn't to worry about this.
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*
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* Parameters:
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* timer: timer to read.
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* Return Value:
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* time units elapsed since last reading.
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* Side Effects:
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* Update internal timestamp.
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*/
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#ifdef HAVE_GCC_ATTRIBUTES
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__attribute__((unused))
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#endif
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static uint64_t tc_timer_elapsed(TCTimer *timer)
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{
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return timer->elapsed(timer);
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}
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/*
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* tc_timer_sleep:
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* blocks caller (thread) for given amount of time units.
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*
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* *PLEASE NOTE*
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* that this function CAN'T guarantee STRICT observancy of
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* sleeping time. It is very likely that blocking time is
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* different (usually greater) than wanted.
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* Providing more guarantees involve deeper interaction with
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* host OS that is out of the scope of this code, yet.
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*
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* Parameters:
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* timer: timer to use.
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* amount: (try to) block caller for this amount of time units.
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* Return Value:
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* 0: succesfully. Blocked for given amount of time units
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* (see note above)
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* -1: failed: an error has caused premature return.
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*/
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#ifdef HAVE_GCC_ATTRIBUTES
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__attribute__((unused))
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#endif
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static int tc_timer_sleep(TCTimer *timer, uint64_t amount)
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{
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return timer->sleep(timer, amount);
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}
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#endif /* TCTIMER_H */
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