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Input: ff-memless - add notion of direction to for rumble effects 

This adds simple direction calculation when combining effects. It's useful
to decide motor direction for rumble (vibrator).

Signed-off-by: Jari Vanhala <ext-jari.vanhala@nokia.com>
Acked-by: Anssi Hannula <anssi.hannula@iki.fi>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
This commit is contained in:
Jari Vanhala 2009-12-24 21:52:20 -08:00 committed by Dmitry Torokhov
parent 1b11c88d3e
commit 94ec26c855
1 changed files with 36 additions and 0 deletions
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36
drivers/input/ff-memless.c
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@ -220,6 +220,22 @@ static int get_compatible_type(struct ff_device *ff, int effect_type)
return 0;
}
/*
* 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.
*/
@ -254,6 +270,19 @@ static void ml_combine_effects(struct ff_effect *effect,
case FF_RUMBLE:
strong = (u32)new->u.rumble.strong_magnitude * gain / 0xffff;
weak = (u32)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 =