x.c

/*
   If not the first time through, we require old_size to be
   at least MINSIZE and to have prev_inuse set.
 */
 
assert ((old_top == initial_top (av) && old_size == 0) ||
        ((unsigned long) (old_size) >= MINSIZE &&
         prev_inuse (old_top) &&
         ((unsigned long) old_end & (pagesize - 1)) == 0));
 
/* Precondition: not enough current space to satisfy nb request */
assert ((unsigned long) (old_size) < (unsigned long) (nb + MINSIZE));