SCI: Implement full kWait behavior

Fixes PQ3 bug #11020

3 files changed, 19 insertions, 6 deletions

diff --git a/engines/sci/engine/kgraphics.cpp b/engines/sci/engine/kgraphics.cpp
index 1e380e2573..a05031059c 100644
--- a/engines/sci/engine/kgraphics.cpp
+++ b/engines/sci/engine/kgraphics.cpp
@@ -394,9 +394,9 @@ reg_t kTextSize(EngineState *s, int argc, reg_t *argv) {
 }
 
 reg_t kWait(EngineState *s, int argc, reg_t *argv) {
-	int sleep_time = argv[0].toUint16();
+	uint16 ticks = argv[0].toUint16();
 
-	const int delta = s->wait(sleep_time);
+	const uint16 delta = s->wait(ticks);
 
 	if (g_sci->_guestAdditions->kWaitHook()) {
 		return NULL_REG;
diff --git a/engines/sci/engine/state.cpp b/engines/sci/engine/state.cpp
index f1c656688c..65d5562ab9 100644
--- a/engines/sci/engine/state.cpp
+++ b/engines/sci/engine/state.cpp
@@ -134,14 +134,26 @@ void EngineState::speedThrottler(uint32 neededSleep) {
 	}
 }
 
-int EngineState::wait(int16 ticks) {
+uint16 EngineState::wait(uint16 ticks) {
 	uint32 time = g_system->getMillis();
-	const int tickDelta = ((long)time - (long)lastWaitTime) * 60 / 1000;
+
+	uint32 ms = ticks * 1000 / 60;
+	uint32 duration = time - lastWaitTime;
+	if (ms > duration) {
+		uint32 sleepTime = ms - duration;
+		sleepTime *= g_debug_sleeptime_factor;
+		g_sci->sleep(sleepTime);
+		time += sleepTime;
+	}
+
+	uint16 tickDelta = (uint16)(((long)time - lastWaitTime) * 60 / 1000);
 	lastWaitTime = time;
+	return tickDelta;
+}
 
+void EngineState::sleep(uint16 ticks) {
 	ticks *= g_debug_sleeptime_factor;
 	g_sci->sleep(ticks * 1000 / 60);
-	return tickDelta;
 }
 
 void EngineState::initGlobals() {
diff --git a/engines/sci/engine/state.h b/engines/sci/engine/state.h
index a299d89446..0ad50a6818 100644
--- a/engines/sci/engine/state.h
+++ b/engines/sci/engine/state.h
@@ -114,7 +114,8 @@ public:
 	uint32 _screenUpdateTime;	/**< The last time the game updated the screen */
 
 	void speedThrottler(uint32 neededSleep);
-	int wait(int16 ticks);
+	uint16 wait(uint16 ticks);
+	void sleep(uint16 ticks);
 
 #ifdef ENABLE_SCI32
 	uint32 _eventCounter; /**< total times kGetEvent was invoked since the last call to kFrameOut */