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.