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i_timer.cpp
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i_timer.cpp
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/*
** i_timer.cpp
**
**---------------------------------------------------------------------------
** Copyright 2012-2015 Alexey Lysiuk
** All rights reserved.
**
** Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions
** are met:
**
** 1. Redistributions of source code must retain the above copyright
** notice, this list of conditions and the following disclaimer.
** 2. Redistributions in binary form must reproduce the above copyright
** notice, this list of conditions and the following disclaimer in the
** documentation and/or other materials provided with the distribution.
** 3. The name of the author may not be used to endorse or promote products
** derived from this software without specific prior written permission.
**
** THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
** IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
** OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
** IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
** NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
** THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
**---------------------------------------------------------------------------
**
*/
#include <assert.h>
#include <sys/sysctl.h>
#include <sys/time.h>
#include <pthread.h>
#include "doomdef.h"
#include "i_system.h"
#include "templates.h"
namespace
{
timeval s_gameStartTicks;
timeval s_systemBootTicks;
unsigned int GetMillisecondsSince(const timeval& time)
{
timeval now;
gettimeofday(&now, NULL);
return static_cast<unsigned int>(
(now.tv_sec - time.tv_sec ) * 1000
+ (now.tv_usec - time.tv_usec) / 1000);
}
bool s_isTicFrozen;
timespec GetNextTickTime()
{
static const long MILLISECONDS_IN_SECOND = 1000;
static const long MICROSECONDS_IN_SECOND = 1000 * MILLISECONDS_IN_SECOND;
static const long NANOSECONDS_IN_SECOND = 1000 * MICROSECONDS_IN_SECOND;
static timespec ts = {};
if (__builtin_expect((0 == ts.tv_sec), 0))
{
timeval tv;
gettimeofday(&tv, NULL);
ts.tv_sec = tv.tv_sec;
ts.tv_nsec = (tv.tv_usec + MICROSECONDS_IN_SECOND / TICRATE) * MILLISECONDS_IN_SECOND;
}
else
{
ts.tv_nsec += (MICROSECONDS_IN_SECOND / TICRATE) * MILLISECONDS_IN_SECOND;
}
if (ts.tv_nsec >= NANOSECONDS_IN_SECOND)
{
ts.tv_sec++;
ts.tv_nsec -= NANOSECONDS_IN_SECOND;
}
return ts;
}
pthread_cond_t s_timerEvent;
pthread_mutex_t s_timerMutex;
pthread_t s_timerThread;
bool s_timerInitialized;
bool s_timerExitRequested;
uint32_t s_ticStart;
uint32_t s_timerStart;
int s_tics;
void* TimerThreadFunc(void*)
{
assert(s_timerInitialized);
assert(!s_timerExitRequested);
while (true)
{
if (s_timerExitRequested)
{
break;
}
const timespec timeToNextTick = GetNextTickTime();
pthread_mutex_lock(&s_timerMutex);
pthread_cond_timedwait(&s_timerEvent, &s_timerMutex, &timeToNextTick);
if (!s_isTicFrozen)
{
__sync_add_and_fetch(&s_tics, 1);
}
s_timerStart = I_MSTime();
pthread_cond_broadcast(&s_timerEvent);
pthread_mutex_unlock(&s_timerMutex);
}
return NULL;
}
int GetTimeThreaded(bool saveMS)
{
if (saveMS)
{
s_ticStart = s_timerStart;
}
return s_tics;
}
int WaitForTicThreaded(int prevTic)
{
assert(!s_isTicFrozen);
while (s_tics <= prevTic)
{
pthread_mutex_lock(&s_timerMutex);
pthread_cond_wait(&s_timerEvent, &s_timerMutex);
pthread_mutex_unlock(&s_timerMutex);
}
return s_tics;
}
void FreezeTimeThreaded(bool frozen)
{
s_isTicFrozen = frozen;
}
} // unnamed namespace
unsigned int I_MSTime()
{
return GetMillisecondsSince(s_gameStartTicks);
}
unsigned int I_FPSTime()
{
return GetMillisecondsSince(s_systemBootTicks);
}
double I_GetTimeFrac(uint32_t* ms)
{
const uint32_t now = I_MSTime();
if (NULL != ms)
{
*ms = s_ticStart + 1000 / TICRATE;
}
return 0 == s_ticStart
? 1.
: clamp<double>( (now - s_ticStart) * TICRATE / 1000., 0, 1);
}
void I_InitTimer()
{
assert(!s_timerInitialized);
s_timerInitialized = true;
gettimeofday(&s_gameStartTicks, NULL);
int mib[2] = { CTL_KERN, KERN_BOOTTIME };
size_t len = sizeof s_systemBootTicks;
sysctl(mib, 2, &s_systemBootTicks, &len, NULL, 0);
pthread_cond_init (&s_timerEvent, NULL);
pthread_mutex_init(&s_timerMutex, NULL);
pthread_create(&s_timerThread, NULL, TimerThreadFunc, NULL);
I_GetTime = GetTimeThreaded;
I_WaitForTic = WaitForTicThreaded;
I_FreezeTime = FreezeTimeThreaded;
}
void I_ShutdownTimer()
{
if (!s_timerInitialized)
{
// This might happen if Cancel button was pressed
// in the IWAD selector window
return;
}
s_timerExitRequested = true;
pthread_join(s_timerThread, NULL);
pthread_mutex_destroy(&s_timerMutex);
pthread_cond_destroy (&s_timerEvent);
}