Ctrl: Let a press shorter than the sample interval be seen once

A press and release that both land between two sceCtrl samples were
lost. Now the next sample sees the button pressed. Idea from Azahar.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Core/HLE/sceCtrl.cpp

@@ -114,6 +114,10 @@ static u32 emuRapidFireInterval = 5;
 // no buttons and centered sticks, as impose does on a PSP. Host-side peeks still see the real state.
 static std::atomic<bool> gameInputBlocked{ false };
 
+// Buttons pressed since the last sample. A press and release that both land between two samples
+// would otherwise never be seen by the game. Guarded by ctrlMutex.
+static u32 ctrlUnsampledPresses = 0;
+
 // These buttons are not affected by rapid fire (neither is analog.)
 const u32 CTRL_EMU_RAPIDFIRE_MASK = CTRL_UP | CTRL_DOWN | CTRL_LEFT | CTRL_RIGHT;
 
@@ -122,7 +126,8 @@ static void __CtrlUpdateLatch()
 	std::lock_guard<std::mutex> guard(ctrlMutex);
 	u64 t = CoreTiming::GetGlobalTimeUs();
 
-	u32 buttons = ctrlCurrent.buttons;
+	u32 buttons = ctrlCurrent.buttons | ctrlUnsampledPresses;
+	ctrlUnsampledPresses = 0;
 	if (emuRapidFire && emuRapidFireToggle)
 		buttons &= CTRL_EMU_RAPIDFIRE_MASK;
 
@@ -284,7 +289,8 @@ void __CtrlUpdateButtons(u32 bitsToSet, u32 bitsToClear)
 
 	std::lock_guard<std::mutex> guard(ctrlMutex);
 	// There's no atomic operation for this, so mutex it is.
-	ctrlCurrent.buttons = (ctrlCurrent.buttons & ~bitsToClear) | bitsToSet;
+	ctrlUnsampledPresses |= bitsToSet & ~ctrlCurrent.buttons;
+	ctrlCurrent.buttons =(ctrlCurrent.buttons & ~bitsToClear) | bitsToSet;
 }
 
 void __CtrlSetAnalogXY(int stick, float x, float y)
@@ -448,6 +454,7 @@ void __CtrlInit() {
 	latch.btnRelease = 0xffffffff;
 
 	gameInputBlocked = false;
+	ctrlUnsampledPresses = 0;
 	memset(&ctrlCurrent, 0, sizeof(ctrlCurrent));
 	memset(ctrlCurrent.analog, CTRL_ANALOG_CENTER, sizeof(ctrlCurrent.analog));
 	analogEnabled = false;
@@ -464,6 +471,9 @@ void __CtrlDoState(PointerWrap &p)
 	if (!s)
 		return;
 
+	// Host input from before the load shouldn't show up in the loaded state.
+	ctrlUnsampledPresses = 0;
+
 	Do(p, analogEnabled);
 	Do(p, ctrlLatchBufs);
 	Do(p, ctrlOldButtons);