int index; /* index of current power */
int tindex; /* index of current temp */
s32 target; /* current target value */
+ s32 last_delta; /* last Tactual - Ttarget */
s32 powers[WF_PID_MAX_HISTORY]; /* power history buffer */
s32 errors[WF_PID_MAX_HISTORY]; /* error history buffer */
s32 temps[2]; /* temp. history buffer */