text: /*
   * C stack frame  (machine frame -- hence "machframe")
   *
   * Decreasing addresses:
   *
   *   arg n
   *   ...
   *   arg 1
   *   saved pc (return address)
   *   saved fp (pointer to caller's frame)_
   *   1st local
   *   ... more locals ...
   *
   */
  
  struct machframe {
  	struct 	machframe *fp;
  	lispval	(*pc)(void);
  	lispval ap[1];
  };
  