SWORD25: Get rid of Kernel::GetMicroTicks()

svn-id: r53403

2 files changed, 28 insertions, 24 deletions

diff --git a/engines/sword25/gfx/graphicengine.cpp b/engines/sword25/gfx/graphicengine.cpp
index ea0c8c82c5..9f3ce665cd 100644
--- a/engines/sword25/gfx/graphicengine.cpp
+++ b/engines/sword25/gfx/graphicengine.cpp
@@ -83,7 +83,7 @@ GraphicEngine::GraphicEngine(Kernel *pKernel) :
 	m_Height(0),
 	m_BitDepth(0),
 	m_Windowed(0),
-	m_LastTimeStamp((uint64) - 1), // max. BS_INT64 um beim ersten Aufruf von _UpdateLastFrameDuration() einen Reset zu erzwingen
+	m_LastTimeStamp((uint) -1), // max. BS_INT64 um beim ersten Aufruf von _UpdateLastFrameDuration() einen Reset zu erzwingen
 	m_LastFrameDuration(0),
 	m_TimerActive(true),
 	m_FrameTimeSampleSlot(0),
@@ -378,23 +378,25 @@ void GraphicEngine::DrawDebugLine(const Vertex &Start, const Vertex &End, uint C
 }
 
 void  GraphicEngine::UpdateLastFrameDuration() {
-	// Aktuelle Zeit holen
-	uint64_t CurrentTime = Kernel::GetInstance()->GetMicroTicks();
-
-	// Verstrichene Zeit seit letztem Frame berechnen und zu große Zeitsprünge ( > 250 msek.) unterbinden
-	// (kann vorkommen bei geladenen Spielständen, während des Debuggings oder Hardwareungenauigkeiten)
-	m_FrameTimeSamples[m_FrameTimeSampleSlot] = static_cast<uint>(CurrentTime - m_LastTimeStamp);
-	if (m_FrameTimeSamples[m_FrameTimeSampleSlot] > 250000) m_FrameTimeSamples[m_FrameTimeSampleSlot] = 250000;
+	// Record current time
+	const uint currentTime = Kernel::GetInstance()->GetMilliTicks();
+
+	// Compute the elapsed time since the last frame and prevent too big ( > 250 msecs) time jumps.
+	// These can occur when loading save states, during debugging or due to hardware inaccuracies.
+	m_FrameTimeSamples[m_FrameTimeSampleSlot] = static_cast<uint>(currentTime - m_LastTimeStamp);
+	if (m_FrameTimeSamples[m_FrameTimeSampleSlot] > 250000)
+		m_FrameTimeSamples[m_FrameTimeSampleSlot] = 250000;
 	m_FrameTimeSampleSlot = (m_FrameTimeSampleSlot + 1) % FRAMETIME_SAMPLE_COUNT;
 
-	// Die Framezeit wird über mehrere Frames gemittelt um Ausreisser zu eliminieren
+	// Compute the average frame duration over multiple frames to eliminate outliers.
 	Common::Array<uint>::const_iterator it = m_FrameTimeSamples.begin();
-	uint Sum = *it;
-	for (it++; it != m_FrameTimeSamples.end(); it++) Sum += *it;
-	m_LastFrameDuration = Sum / FRAMETIME_SAMPLE_COUNT;
+	uint sum = *it;
+	for (it++; it != m_FrameTimeSamples.end(); it++)
+		sum += *it;
+	m_LastFrameDuration = sum * 1000 / FRAMETIME_SAMPLE_COUNT;
 
-	// _LastTimeStamp auf die Zeit des aktuellen Frames setzen
-	m_LastTimeStamp = CurrentTime;
+	// Update m_LastTimeStamp with the current frame's timestamp
+	m_LastTimeStamp = currentTime;
 }
 
 namespace {
diff --git a/engines/sword25/gfx/graphicengine.h b/engines/sword25/gfx/graphicengine.h
index 019f5eec4c..ecbfa377c8 100644
--- a/engines/sword25/gfx/graphicengine.h
+++ b/engines/sword25/gfx/graphicengine.h
@@ -189,17 +189,19 @@ public:
 	/**
 	 * Specifies the time (in microseconds) since the last frame has passed
 	 */
-	int GetLastFrameDurationMicro() {
-		if (m_TimerActive) return m_LastFrameDuration;
-		else return 0;
+	int GetLastFrameDurationMicro() const {
+		if (!m_TimerActive)
+			return 0;
+		return m_LastFrameDuration;
 	}
 
 	/**
 	 * Specifies the time (in microseconds) the previous frame took
 	*/
-	float GetLastFrameDuration() {
-		if (m_TimerActive) return static_cast<float>(m_LastFrameDuration) / 1000000.0f;
-		else return 0;
+	float GetLastFrameDuration() const {
+		if (!m_TimerActive)
+			return 0;
+		return static_cast<float>(m_LastFrameDuration) / 1000000.0f;
 	}
 
 	void StopMainTimer() {
@@ -208,7 +210,7 @@ public:
 	void ResumeMainTimer() {
 		m_TimerActive = true;
 	}
-	float GetSecondaryFrameDuration() {
+	float GetSecondaryFrameDuration() const {
 		return static_cast<float>(m_LastFrameDuration) / 1000000.0f;
 	}
 
@@ -217,14 +219,14 @@ public:
 	/**
 	 * Returns the width of the output buffer in pixels
 	 */
-	int         GetDisplayWidth() {
+	int         GetDisplayWidth() const {
 		return m_Width;
 	}
 
 	/**
 	 * Returns the height of the output buffer in pixels
 	 */
-	int         GetDisplayHeight() {
+	int         GetDisplayHeight() const {
 		return m_Height;
 	}
 
@@ -365,7 +367,7 @@ private:
 
 	// LastFrameDuration Variables
 	// ---------------------------
-	uint64                      m_LastTimeStamp;
+	uint                      m_LastTimeStamp;
 	uint                m_LastFrameDuration;
 	bool                        m_TimerActive;
 	Common::Array<uint> m_FrameTimeSamples;