MOHAWK: RIVEN: Delay less for slower systems

Some systems may take longer to process the game loop
than others so we delay by a variable amount so faster
and slower system execute the game loop the same number
of times per second (the fps is capped at 100).

Slower systems that take longer than 10ms to process the game
loop won't have any delay.

2 files changed, 5 insertions, 1 deletions

diff --git a/engines/mohawk/riven.cpp b/engines/mohawk/riven.cpp
index 37a7745d34..057102260d 100644
--- a/engines/mohawk/riven.cpp
+++ b/engines/mohawk/riven.cpp
@@ -209,6 +209,7 @@ Common::Error MohawkEngine_Riven::run() {
 
 void MohawkEngine_Riven::doFrame() {
 	// Update background running things
+	uint32 loopStart = _system->getMillis();
 	_sound->updateSLST();
 	_video->updateMovies();
 
@@ -234,9 +235,11 @@ void MohawkEngine_Riven::doFrame() {
 
 	// Update the screen once per frame
 	_system->updateScreen();
+	uint32 loopElapsed = _system->getMillis() - loopStart;
 
 	// Cut down on CPU usage
-	_system->delayMillis(10);
+	if (loopElapsed < 10)
+		_system->delayMillis(10 - loopElapsed);
 }
 
 void MohawkEngine_Riven::processInput() {
diff --git a/engines/mohawk/riven.h b/engines/mohawk/riven.h
index b887fc1184..e938d2711c 100644
--- a/engines/mohawk/riven.h
+++ b/engines/mohawk/riven.h
@@ -106,6 +106,7 @@ public:
 	bool hasFeature(EngineFeature f) const override;
 
 	void doFrame();
+	void processInput();
 
 private:
 	// Datafiles