/* heapsort.h */
void heapsort( void *base, int nmemb, int size, int (*compar)() );
  /* base is pointer to start of area to be sorted */
  /* nmemb is number of members to be sorted, 0 to nmemb-1 */
  /* size is sizeof( a member, sort key plus other optional data */
  /* int compar(void *memb1, void *memb2); to be provided.
         typically return memcmp(memb1, memb2, sizeof(sort key) ); */