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/* ========================================================================= */
/**
* @file fsm.h
* Event-driven finite state machine.
*
* @copyright
* Copyright 2023 Google LLC
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef __WLMTK_FSM_H__
#define __WLMTK_FSM_H__
#include <libbase/libbase.h>
#include <stdbool.h>
#include <stddef.h>
#ifdef __cplusplus
extern "C" {
#endif // __cplusplus
/** Forward declaration. */
typedef struct _wlmtk_fsm_t wlmtk_fsm_t;
/** State machine definition. */
typedef struct {
/** State before receiving the event. */
int state;
/** Event. */
int event;
/** Upon having (state, event): State to transition to. */
int to_state;
/** Handler for the activity at (state, event). */
bool (*handler)(wlmtk_fsm_t *fsm_ptr, void *ud_ptr);
} wlmtk_fsm_transition_t;
/** Finite state machine. State. */
struct _wlmtk_fsm_t {
/** The transitions table. */
const wlmtk_fsm_transition_t *transitions;
/** Current state. */
int state;
};
/** Sentinel element for state transition table. */
#define WLMTK_FSM_TRANSITION_SENTINEL { \
.state = -1, \
.event = -1, \
.to_state = -1, \
.handler = NULL, \
}
/**
* Initializes the finite-state machine.
*
* @param fsm_ptr
* @param transitions
* @param initial_state
*/
void wlmtk_fsm_init(
wlmtk_fsm_t *fsm_ptr,
const wlmtk_fsm_transition_t *transitions,
int initial_state);
/**
* Handles an event for the finite-state machine.
*
* Will search for the transition matching (current state, event) and call the
* associate handler.
*
* @param fsm_ptr
* @param event
* @param ud_ptr
*
* @return If a matching transition was found: The return value of the
* associated handler (or true, if no handler was given). Otherwise,
* returns false.
*/
bool wlmtk_fsm_event(
wlmtk_fsm_t *fsm_ptr,
int event,
void *ud_ptr);
/** Unit tests for the finite-state machine. */
extern const bs_test_case_t wlmtk_fsm_test_cases[];
#ifdef __cplusplus
} // extern "C"
#endif // __cplusplus
#endif /* __WLMTK_FSM_H__ */
/* == End of fsm.h ====================================================== */
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