suse man page for struct_ff_periodic_effect

STRUCT 
FF_PERIODIC_E(9) 					  Input Subsystem					   STRUCT FF_PERIODIC_E(9)

NAME
       struct_ff_periodic_effect - defines parameters of a periodic force-feedback effect

SYNOPSIS
       struct ff_periodic_effect {
	 __u16 waveform;
	 __u16 period;
	 __s16 magnitude;
	 __s16 offset;
	 __u16 phase;
	 struct ff_envelope envelope;
	 __u32 custom_len;
	 __s16 __user * custom_data;
       };

MEMBERS
       waveform
	   kind of the effect (wave)

       period
	   period of the wave (ms)

       magnitude
	   peak value

       offset
	   mean value of the wave (roughly)

       phase
	   'horizontal' shift

       envelope
	   envelope data

       custom_len
	   number of samples (FF_CUSTOM only)

       custom_data
	   buffer of samples (FF_CUSTOM only)

DESCRIPTION
       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.

NOTE
       the data pointed by custom_data is copied by the driver. You can therefore dispose of the memory after the upload/update.

COPYRIGHT
Kernel Hackers Manual 2.6.					     July 2010						   STRUCT FF_PERIODIC_E(9)