Hierarchical Finite State Machine

20.10.0

The ETL's etl::hfsm is derived from etl::fsm and utilises the same state template classes.

See etl::fsm

Note:

For an etl::hfsm, on_enter_state() cannot force a state change. It must return etl::ifsm_state::No_State_Change.

If it does not, then an ETL_ASSERT will be raised.

Defines etl::hfsm plus all defined in fsm.h.

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hfsm

The state machine.

Inherits from etl::fsm.

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hfsm(etl::message_router_id_t id)

Constructor.

Sets the router id for the HFSM.

The HFSM is not started.

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void receive(const etl::imessage& message)

Top level message handler for the HFSM.

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Errors

Additional errors to etl::fsm.

fsm_state_composite_state_change_forbidden

Inherits from etl::fsm_exception

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Example

// The states.

Idle idle;

Running running;

WindingUp windingUp;

WindingDown windingDown;

AtSpeed atSpeed;

struct StateId

{

enum

{

Idle,

Running,

Winding_Up,

Winding_Down,

At_Speed,

Number_Of_States

};

}

struct EventId

{

enum

{

Start,

Stop,

EStop,

Stopped,

Set_Speed,

Timeout

};

// These are all of the states for this HSFM.

etl::ifsm_state* stateList[StateId::Number_Of_States] =

{

&idle, &running, &windingUp, &windingDown, &atSpeed

};

// These states are child states of 'Running'.

etl::ifsm_state* childStates[] =

{

&windingUp, &atSpeed, &windingDown

};

MotorControl motorControl;

running.set_child_states(childStates, etl::size(childStates));

motorControl.Initialise(stateList, etl::size(stateList));

hfsm.h