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/**
@file Stopwatch.cpp
@maintainer Morgan McGuire, matrix@graphics3d.com
@created 2005-10-05
@edited 2005-10-05
Copyright 2000-2003, Morgan McGuire.
All rights reserved.
*/
#include "G3D/Stopwatch.h"
#include "G3D/System.h"
namespace G3D {
Stopwatch::Stopwatch() : inBetween(false), lastTockTime(-1),
lastDuration(0), lastCycleCount(0), m_fps(0), emwaFPS(0),
m_smoothFPS(0), emwaDuration(0) {
computeOverhead();
}
void Stopwatch::computeOverhead() {
cycleOverhead = 0;
tick();
tock();
cycleOverhead = elapsedCycles();
}
void Stopwatch::tick() {
// This is 'alwaysAssert' instead of 'debugAssert'
// since people rarely profile in debug mode.
alwaysAssertM(! inBetween, "Stopwatch::tick() called twice in a row.");
inBetween = true;
// We read RDTSC twice here, but it is more abstract to implement this
// way and at least we're reading the cycle count last.
timeStart = System::time();
System::beginCycleCount(cycleStart);
}
void Stopwatch::tock() {
System::endCycleCount(cycleStart);
RealTime now = System::time();
lastDuration = now - timeStart;
if (abs(emwaDuration - lastDuration) > max(emwaDuration, lastDuration) * 0.50) {
// Off by more than 50%
emwaDuration = lastDuration;
} else {
emwaDuration = lastDuration * 0.05 + emwaDuration * 0.95;
}
lastCycleCount = cycleStart - cycleOverhead;
if (lastCycleCount < 0) {
lastCycleCount = 0;
}
if (lastTockTime != -1.0) {
m_fps = 1.0 / (now - lastTockTime);
// Time smooth the average
emwaFPS = m_fps * 0.01 + emwaFPS * 0.99;
if (abs(emwaFPS - m_fps) > max(emwaFPS, m_fps) * 0.08) {
// The difference between emwa and m_fps is way off
// update emwa directly.
emwaFPS = m_fps;
}
// Update m_smoothFPS only when the value varies significantly
// We round so as to not mislead the user as to the accuracy of
// the number.
if (m_smoothFPS == 0) {
m_smoothFPS = m_fps;
} else if (emwaFPS <= 10) {
if (::fabs(m_smoothFPS - emwaFPS) > .75) {
m_smoothFPS = floor(emwaFPS * 10.0 + 0.5) / 10.0;
}
} else {
if (::fabs(m_smoothFPS - emwaFPS) > 1.25) {
m_smoothFPS = floor(emwaFPS + 0.5);
}
}
}
lastTockTime = now;
alwaysAssertM(inBetween, "Stopwatch::tock() called without matching tick.");
inBetween = false;
}
}
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