GBA GPIO: Fix gyro read-out start (fixes #3141)

CHANGES

@@ -12,6 +12,7 @@ Emulation fixes:
  - GB Video: Implement DMG-style sprite ordering
  - GBA: Unhandled bkpt should be treated as an undefined exception
  - GBA GPIO: Fix tilt scale and orientation (fixes mgba.io/i/2703)
+ - GBA GPIO: Fix gyro read-out start (fixes mgba.io/i/3141)
  - GBA I/O: Fix HALTCNT access behavior (fixes mgba.io/i/2309)
  - GBA SIO: Fix MULTI mode SIOCNT bit 7 writes on secondary GBAs (fixes mgba.io/i/3110)
  - GBA Video: Disable BG target 1 blending when OBJ blending (fixes mgba.io/i/2722)

src/gba/cart/gpio.c

@@ -320,18 +320,20 @@ void _gyroReadPins(struct GBACartridgeHardware* hw) {
 		return;
 	}
 
+	// Write bit on falling edge
+	bool doOutput = hw->gyroEdge && !(hw->pinState & 2);
 	if (hw->pinState & 1) {
 		if (gyro->sample) {
 			gyro->sample(gyro);
 		}
 		int32_t sample = gyro->readGyroZ(gyro);
 
-		// Normalize to ~12 bits, focused on 0x6C0
+		// Normalize to ~12 bits, focused on 0x700
-		hw->gyroSample = (sample >> 21) + 0x6C0; // Crop off an extra bit so that we can't go negative
+		hw->gyroSample = (sample >> 21) + 0x700; // Crop off an extra bit so that we can't go negative
+		doOutput = true;
 	}
 
-	if (hw->gyroEdge && !(hw->pinState & 2)) {
+	if (doOutput) {
-		// Write bit on falling edge
 		unsigned bit = hw->gyroSample >> 15;
 		hw->gyroSample <<= 1;
 		_outputPins(hw, bit << 2);

src/platform/3ds/main.c

@@ -704,7 +704,7 @@ static int32_t _readTiltY(struct mRotationSource* source) {
 
 static int32_t _readGyroZ(struct mRotationSource* source) {
 	struct m3DSRotationSource* rotation = (struct m3DSRotationSource*) source;
-	return rotation->gyro.y << 18L; // Yes, y
+	return rotation->gyro.y << 17L; // Yes, y
 }
 
 static void _startRequestImage(struct mImageSource* source, unsigned w, unsigned h, int colorFormats) {

src/platform/libretro/libretro.c

@@ -1390,7 +1390,7 @@ static void _updateRotation(struct mRotationSource* source) {
 		tiltY = sensorGetCallback(0, RETRO_SENSOR_ACCELEROMETER_Y) * 2e8f;
 	}
 	if (gyroEnabled) {
-		gyroZ = sensorGetCallback(0, RETRO_SENSOR_GYROSCOPE_Z) * -1.1e9f;
+		gyroZ = sensorGetCallback(0, RETRO_SENSOR_GYROSCOPE_Z) * -5.5e8f;
 	}
 }
 

src/platform/psp2/psp2-context.c

@@ -149,7 +149,7 @@ static int32_t _readTiltY(struct mRotationSource* source) {
 
 static int32_t _readGyroZ(struct mRotationSource* source) {
 	struct mSceRotationSource* rotation = (struct mSceRotationSource*) source;
-	return rotation->state.gyro.z * -0x10000000;
+	return rotation->state.gyro.z * -0x8000000;
 }
 
 static void _setRumble(struct mRumble* source, int enable) {

src/platform/sdl/sdl-events.c

@@ -823,14 +823,14 @@ static void _mSDLRotationSample(struct mRotationSource* source) {
 			float theta[3];
 			int count = SDL_GameControllerGetSensorData(controller, SDL_SENSOR_GYRO, theta, 3);
 			if (count >= 0) {
-				rotation->zDelta = theta[1] / -10.f;
+				rotation->zDelta = theta[1] / -20.f;
 			}
 			return;
 		}
 	}
 #endif
 	if (rotation->gyroZ >= 0) {
-		rotation->zDelta = SDL_JoystickGetAxis(rotation->p->joystick->joystick, rotation->gyroZ) / 1.e5f;
+		rotation->zDelta = SDL_JoystickGetAxis(rotation->p->joystick->joystick, rotation->gyroZ) / 2.e5f;
 		return;
 	}
 

src/platform/switch/main.c

@@ -644,7 +644,7 @@ void _sampleRotation(struct mRotationSource* source) {
 	}
 	tiltX = sixaxis.acceleration.x * 3e8f;
 	tiltY = sixaxis.acceleration.y * -3e8f;
-	gyroZ = sixaxis.angular_velocity.z * -1.1e9f;
+	gyroZ = sixaxis.angular_velocity.z * -5.5e8f;
 }
 
 int32_t _readTiltX(struct mRotationSource* source) {

src/platform/wii/main.c

@@ -1731,7 +1731,7 @@ void _sampleRotation(struct mRotationSource* source) {
 		return;
 	}
 	gyroZ = exp.mp.rz - 0x1FA0;
-	gyroZ <<= 18;
+	gyroZ <<= 17;
 }
 
 int32_t _readTiltX(struct mRotationSource* source) {