cpp/openttd-patchpack/source Changeset - r25890:31b085404537

Changeset - r25890:31b085404537

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Michael Lutz - 3 years ago 2021-08-15 10:14:53
michi@icosahedron.de

Fix 2183fd4d: [NewGRF] Use divide instead of right shift for signed numbers. (#9480)

"For negative a, the value of a >> b is implementation-defined (in most implementations, this performs arithmetic right shift, so that the result remains negative)."

2 files changed with 2 insertions and 2 deletions:

src/newgrf_engine.cpp

src/train_cmd.cpp

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src/newgrf_engine.cpp

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@@ @@ -1180,25 +1180,25 @@ uint16 GetVehicleCallbackParent(Callback @@
 int GetVehicleProperty(const Vehicle *v, PropertyID property, int orig_value, bool is_signed)
+{
 	return GetEngineProperty(v->engine_type, property, orig_value, v, is_signed);
+}
 int GetEngineProperty(EngineID engine, PropertyID property, int orig_value, const Vehicle *v, bool is_signed)
+{
 	uint16 callback = GetVehicleCallback(CBID_VEHICLE_MODIFY_PROPERTY, property, 0, engine, v);
 	if (callback != CALLBACK_FAILED) {
 		if (is_signed) {
 			/* Sign extend 15 bit integer */
-			return static_cast<int16>(callback << 1) >> 1;
+			return static_cast<int16>(callback << 1) / 2;
 		} else {
 			return callback;
+		}
+	}
 	return orig_value;
+}
 static void DoTriggerVehicle(Vehicle *v, VehicleTrigger trigger, byte base_random_bits, bool first)
+{
 	/* We can't trigger a non-existent vehicle... */

src/train_cmd.cpp

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@@ @@ -354,25 +354,25 @@ int Train::GetCurveSpeedLimit() const @@
 	if (max_speed != absolute_max_speed) {
 		/* Apply the current railtype's curve speed advantage */
 		const RailtypeInfo *rti = GetRailTypeInfo(GetRailType(this->tile));
 		max_speed += (max_speed / 2) * rti->curve_speed;
 		if (this->tcache.cached_tilt) {
 			/* Apply max_speed bonus of 20% for a tilting train */
 			max_speed += max_speed / 5;
+		}
 		/* Apply max_speed modifier (cached value is fixed-point binary with 8 fractional bits)
 		 * and clamp the result to an acceptable range. */
-		max_speed += (max_speed * this->tcache.cached_curve_speed_mod) >> 8;
+		max_speed += (max_speed * this->tcache.cached_curve_speed_mod) / 256;
 		max_speed = Clamp(max_speed, 2, absolute_max_speed);
+	}
 	return max_speed;
+}
 /**
  * Calculates the maximum speed of the vehicle under its current conditions.
  * @return Maximum speed of the vehicle.
  */
 int Train::GetCurrentMaxSpeed() const
+{

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