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/** hsm.h -- Hierarchical State Machine interface 
 * M. Samek, 01/07/00 
 */ 
#ifndef hsm_h 
#define hsm_h 

typedef int Event; 
typedef struct { 
  Event evt; 
} Msg; 
 
typedef struct Hsm Hsm; 
typedef Msg const *(*EvtHndlr)(Hsm*, Msg const*); 
 
typedef struct State State; 
struct State { 
  State *super;                  /* pointer to superstate */ 
  EvtHndlr hndlr;             /* state's handler function */ 
  char const *name; 
}; 
 
void StateCtor(State *me, char const *name, 
               State *super, EvtHndlr hndlr); 
#define StateOnEvent(me_, ctx_, msg_)\ 
  (*(me_)->hndlr)((ctx_), (msg_)) 
 
struct Hsm {     /* Hierarchical State Machine base class */ 
  char const *name;             /* pointer to static name */ 
  State *curr;                           /* current state */ 
  State *next;  /* next state (non 0 if transition taken) */ 
  State top;                     /* top-most state object */ 
}; 
 
void HsmCtor(Hsm *me, char const *name, EvtHndlr topHndlr); 
void HsmOnStart(Hsm *me); /*enter and start the top state */ 
void HsmOnEvent(Hsm *me, Msg const *msg); /* "HSM engine" */ 
 
/* protected: */ 
unsigned char HsmToLCA_(Hsm *me, State *target); 
void HsmExit_(Hsm *me, unsigned char toLca); 
#define STATE_CURR(me_) (((Hsm *)me_)->curr) 
#define STATE_START(me_, target_) \ 
  (assert(((Hsm *)me_)->next == 0),\ 
    ((Hsm *)me_)->next = (target_)) 
 
#define STATE_TRAN(me_, target_) if (1) { \ 
  static unsigned char toLca_ = 0; \ 
  assert(((Hsm *)me_)->next == 0);\ 
  if (toLca_ == 0) \ 
      toLca_ = HsmToLCA_((Hsm *)(me_), (target_));\ 
  HsmExit_((Hsm *)(me_), toLca_);\ 
  ((Hsm *)(me_))->next = (target_);\ 
} else ((void)0) 
 
#define START_EVT ((Event)(-1)) 
#define ENTRY_EVT ((Event)(-2)) 
#define EXIT_EVT  ((Event)(-3)) 

#endif /* hsm_h */