hsm.h

用于协议状态机的编程参考

/** 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 */