• Elias Vanderstuyft's avatar
    Input: document and check on implicitly defined FF_MAX_EFFECTS · 33b96d93
    Elias Vanderstuyft authored
    There is an undocumented upper bound for the total number of ff effects:
        FF_GAIN (= 96).
    This can be found as follows:
    - user: write(EV_FF, effect_id, iterations)
        calls kernel: ff->playback(effect_id, ...): starts effect "effect_id"
    - user: write(EV_FF, FF_GAIN, gain)
        calls kernel: ff->set_gain(gain, ...): sets gain
    A collision occurs when effect_id equals FF_GAIN.
    According to input_ff_event(),
    FF_GAIN is the smallest value where a collision occurs.
    Therefore the greatest safe value for effect_id is FF_GAIN - 1,
    and thus the total number of effects should never exceed FF_GAIN.
    Define FF_MAX_EFFECTS as FF_GAIN and check on this limit in ff-core.
    Signed-off-by: default avatarElias Vanderstuyft <elias.vds@gmail.com>
    Signed-off-by: default avatarDmitry Torokhov <dmitry.torokhov@gmail.com>
ff-core.c 9.03 KB