pgetcurr
pprevious = pgetcurr(PNULL);
pcurrent = pgetcurr(pp);
if ((pcurrent = pgetcurr(PNULL)) == PNULL)
pprevious = pgetcurr(pp);
pcurrent = pgetcurr(pp);
pprevious = pgetcurr(pp);
pprevious = pgetcurr(pp);
struct process *pgetcurr(struct process *);