input.h changes

[Johann D. <jo...@Do...>]

Hi,

I am changing the ff_effect struct. I went for the 1-parameter-1-effect
scheme (actually it's really (1,2)-parameter(s)-1-effect).

New effect types:
* FF_DAMPER
This effect really is the former FF_FRICTION.
* FF_INERTIA
* FF_RAMP
Note that this effect is not periodic. Reasons:
 1. PID does not define it as a periodic effect
 2. A periodic ramp is just a sawtooth up or down
I wonder if we still need the FF_CONSTANT, as it's just a special case of
FF_RAMP.
* FF_CUSTOM
It's not new actually. I just did not remember it was there.

New or changed structures:
* Ramp effects
struct ff_ramp_effect {
        _s16 start_level;
        _s16 end_level;
        struct ff_shape shape;
}
* Friction
No new structure. We can use the ff_interactive, according to PID. What is
its meaning is still not clear. I would guess the following:
force = f(position, direction)
force.direction = -direction
force.magnitude = p(position), p being the function described at page 12.
The ff_interactive_effect structure has changed:
struct ff_interactive_effect {
        __u16 right_saturation[2]; /* Max level when joystick is on the
right */
        __u16 left_saturation[2];  /* Max level when joystick in on the
left */

        __s16 right_coeff[2];   /* Indicates how fast the force grows when
the
                                   joystick moves to the right */
        __s16 left_coeff[2];    /* Same for left side */

        __u16 deadband[2];      /* Size of area where no force is produced
*/
        __s16 center[2];        /* Position of dead zone */

};

Note the arrays. There is one value for each axis. The axis mumber has
become useless and has therefore been droped.

* ff_periodic_effect:
struct ff_periodic_effect {
        __u16 waveform;         /* Kind of wave (sine, square...) */
        __u16 period;           /* in ms */
        __s16 magnitude;        /* Peak value */
        __s16 offset;           /* Mean value of wave (roughly) */
        __u16 phase;            /* 'Horizontal' shift */

        struct ff_shape shape;

/* Only used if waveform == FF_CUSTOM */
        __u32 custom_len;       /* Number of samples  */
        __s16 *custom_data;     /* Buffer of samples */
/* Note: the data pointed by custom_data is copied by the driver. You can
 * therefore dispose of the memory after the upload/update */
};

The _u32 for the number of samples is a bit oversized, maybe.


I think that's all for now. Comments and critics welcome.

-- 
Johann Deneux