xref: /btstack/src/btstack_hsm.h (revision bb8a927b64a2bed4835a6cf12ebf71eb29487bd9)

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/**
 * @title Hierarchical State Machine (HSM)
 *
 */

#ifndef BTSTACK_HSM_H
#define BTSTACK_HSM_H

#if defined __cplusplus
extern "C" {
#endif

#include <stdint.h>

typedef uint16_t btstack_hsm_signal_t;
enum btstack_hsm_reserved_signals_e {
    BTSTACK_HSM_EMPTY_SIG,
    BTSTACK_HSM_INIT_SIG,
    BTSTACK_HSM_ENTRY_SIG,
    BTSTACK_HSM_EXIT_SIG,
    BTSTACK_HSM_USER_SIG
};

typedef struct {
    btstack_hsm_signal_t sig;
} btstack_hsm_event_t;
typedef struct btstack_hsm_s btstack_hsm_t;
typedef enum {
    BTSTACK_HSM_TRAN_STATUS,
    BTSTACK_HSM_SUPER_STATUS,
    BTSTACK_HSM_HANDLED_STATUS,
    BTSTACK_HSM_UNHANDLED_STATUS,
    BTSTACK_HSM_IGNORED_STATUS
} btstack_hsm_state_t;

typedef btstack_hsm_state_t (*btstack_hsm_state_handler_t)(btstack_hsm_t * const me, btstack_hsm_event_t const * const e);

struct btstack_hsm_s {
    btstack_hsm_state_handler_t state;
    btstack_hsm_state_handler_t temp;
    btstack_hsm_state_handler_t *path;
    int_fast8_t depth;
};

/* API_START */

/*
 * @brief Request the transition from the current state to the given new state
 * @param me the current state machine
 * @param target the new state to transit to
 * @result transition status
 */
btstack_hsm_state_t btstack_hsm_transit(btstack_hsm_t * const me, btstack_hsm_state_handler_t const target);

/*
 * @brief Specifies the upper state in a state hierarchy
 * @param me the current state machine
 * @param target the next parent state in the hierarchy
 * @result transition status
 */
btstack_hsm_state_t btstack_hsm_super(btstack_hsm_t * const me, btstack_hsm_state_handler_t const target);

/*
 * @brief Placeholder state to mark the top most state in a state hierarchy, the root state. Ignores all events.
 * @param me the current state machine
 * @param e event
 * @result ignored status
 */
btstack_hsm_state_t btstack_hsm_top(btstack_hsm_t * const me, btstack_hsm_event_t const * const e);

/*
 * @brief Constructs a new state hierarchical machine machine, with storage for maximum hierarchy depth.
 * @param me the current state machine
 * @param initial the initial state
 * @param array of btstack_hsm_state_handler_t elements with the same number of elements as the maximum number of nested state machines.
 * @param The number of nested state machines.
 */
void btstack_hsm_constructor(btstack_hsm_t * const me, btstack_hsm_state_handler_t initial, btstack_hsm_state_handler_t path[], int8_t depth);

/*
 * @brief Takes the initial transition of the state machine and sending it a BTSTACK_HSM_INIT_SIG
 * @param me the current state machine
 * @param e event
 */
void btstack_hsm_init(btstack_hsm_t * const me, btstack_hsm_event_t const * const e);

/*
 * @brief Dispatches the given event to the state machine, if a transition is requested, leave the old states and enter the new on.
 *        Honoring the hierarchy and handling entering/exiting all states on the way.
 * @param me the current state machine
 * @param e event
 */
btstack_hsm_state_t btstack_hsm_dispatch(btstack_hsm_t * const me, btstack_hsm_event_t const * const e);

/* API_END */

#if defined __cplusplus
}
#endif

#endif