+static ispt_struct *ispt_freelist = 0;
+
+static ISPT ispt_alloc()
+{
+ ISPT p;
+
+ if (ispt_freelist)
+ {
+ p = ispt_freelist;
+ ispt_freelist = ispt_freelist->next;
+ }
+ else
+ p = xmalloc(sizeof(ispt_struct));
+ return p;
+}
+
+static void ispt_free(ISPT pt)
+{
+ pt->next = ispt_freelist;
+ ispt_freelist = pt;
+}