struct ff_periodic_effect — defines parameters of a periodic force-feedback effect
struct ff_periodic_effect {
__u16 waveform;
__u16 period;
__s16 magnitude;
__s16 offset;
__u16 phase;
struct ff_envelope envelope;
__u32 custom_len;
__s16 * custom_data;
}; kind of the effect (wave)
period of the wave (ms)
peak value
mean value of the wave (roughly)
'horizontal' shift
envelope data
number of samples (FF_CUSTOM only)
buffer of samples (FF_CUSTOM only)
Known waveforms - FF_SQUARE, FF_TRIANGLE, FF_SINE, FF_SAW_UP, FF_SAW_DOWN, FF_CUSTOM. The exact syntax FF_CUSTOM is undefined for the time being as no driver supports it yet.
the data pointed by custom_data is copied by the driver. You can therefore dispose of the memory after the upload/update.