@@ -221,6 +221,22 @@ static int get_compatible_type(struct ff_device *ff, int effect_type)
}
/*
+ * Only left/right direction should be used (under/over 0x8000) for
+ * forward/reverse motor direction (to keep calculation fast & simple).
+ */
+static u16 ml_calculate_direction(u16 direction, u16 force,
+ u16 new_direction, u16 new_force)
+{
+ if (!force)
+ return new_direction;
+ if (!new_force)
+ return direction;
+ return (((u32)(direction >> 1) * force +
+ (new_direction >> 1) * new_force) /
+ (force + new_force)) << 1;
+}
+
+/*
* Combine two effects and apply gain.
*/
static void ml_combine_effects(struct ff_effect *effect,
@@ -254,6 +270,19 @@ static void ml_combine_effects(struct ff_effect *effect,
case FF_RUMBLE:
strong = new->u.rumble.strong_magnitude * gain / 0xffff;
weak = new->u.rumble.weak_magnitude * gain / 0xffff;
+
+ if (effect->u.rumble.strong_magnitude + strong)
+ effect->direction = ml_calculate_direction(
+ effect->direction,
+ effect->u.rumble.strong_magnitude,
+ new->direction, strong);
+ else if (effect->u.rumble.weak_magnitude + weak)
+ effect->direction = ml_calculate_direction(
+ effect->direction,
+ effect->u.rumble.weak_magnitude,
+ new->direction, weak);
+ else
+ effect->direction = 0;
effect->u.rumble.strong_magnitude =
min(strong + effect->u.rumble.strong_magnitude,
0xffffU);
@@ -268,6 +297,13 @@ static void ml_combine_effects(struct ff_effect *effect,
/* here we also scale it 0x7fff => 0xffff */
i = i * gain / 0x7fff;
+ if (effect->u.rumble.strong_magnitude + i)
+ effect->direction = ml_calculate_direction(
+ effect->direction,
+ effect->u.rumble.strong_magnitude,
+ new->direction, i);
+ else
+ effect->direction = 0;
effect->u.rumble.strong_magnitude =
min(i + effect->u.rumble.strong_magnitude, 0xffffU);
effect->u.rumble.weak_magnitude =