State Machine Implementation

This basic state machine implementation shows the basic concept of a state machine where each state is represented by a data object that contains function points to an init, enter, run and exit function. More...

Functions
unsigned char	uStatesInit (void)
	Initialized the states stored in the state machine by calling their probe functions, if set. More...
unsigned char	uStatesRun (void)
	Ticks the state machine over. More...
int	xStatesAdd (void(*probe)(void), void(*enter)(void), void(*run)(void), void(*exit)(void), int ID, char *name)
	Adds a state to the state machine. More...
void	vStatesSetCallback (void(*callback)(void))
	Sets the callback function for the state machine. More...
void	vStatesSetData (void *data)
	Sets the data of the current state. More...
void	vStatesSetInput (unsigned char input)
	Sets the input variable stored in the state machine. More...
unsigned char	uStatesSetState (unsigned int state_id)
	Sets the next state of the state machine using the state's ID. More...
void *	pStatesGetData (void)
	Returns a pointer to the data stored in the current state. More...
char *	pStatesGetStateName (void)
	Returns the string of the current state's name. More...
unsigned char	uStatesGetInput (void)
	Retrieves the input vector stored within the state machine. More...
int	xStatesGetStateID (void)
	Returns the ID of the current state. More...
int	xStatesGetStateCount (void)
	Returns the number of states currently stored within the state machine. More...
int	xStatesIncrementState (void)
	Increments the state to the next in the linked list of states. More...
int	xStatesDecrementState (void)
	Decrements the state to the previous in the linked list of states. More...
void	vStatesClearInput (void)
	Clears the 8 bit input vector stored in the state machine. More...

Detailed Description

This basic state machine implementation shows the basic concept of a state machine where each state is represented by a data object that contains function points to an init, enter, run and exit function.

Basic use of this framework requires the user to firstly add the states using

xStatesAdd(init_function, enter_function, run_function, exit_function, ID, name_string)

The handler functions take the form seen in xStatesAdd().

Once the states have been added an optional callback can be set for the state machine. It runs after the execution of each state machine cycle. This is set using

vStatesSetCallback(callback_function)

The states can then be initialized such that their probe functions are called. This is done using

uStatesInit()

The initial state can be set using

uStatesSetState(state_ID)

Otherwise the first state added is run by default. This call is the same that is used to change state during the machines execution.

Function Documentation

pStatesGetData()

void* pStatesGetData

(

void

)

Returns a pointer to the data stored in the current state.

The data is stored using a void pointer and must be type cast once returned.

Returns

void * to the data

pStatesGetStateName()

char* pStatesGetStateName

(

void

)

Returns the string of the current state's name.

Returns

char * to the string

uStatesGetInput()

unsigned char uStatesGetInput

(

void

)

Retrieves the input vector stored within the state machine.

Returns

unsigned char 8 bit input vector

uStatesInit()

unsigned char uStatesInit

(

void

)

Initialized the states stored in the state machine by calling their probe functions, if set.

Returns

0 on success

First added state is the initial state if possible

uStatesRun()

unsigned char uStatesRun

(

void

)

Ticks the state machine over.

A call to states_run will cause the state machine to check if a state change is pending, if so then the appropriate exit and enter functions for the current and next states will be called. The run function of the next state will be run after the state change. If there is no state change to be done then the run function of the current state is simply called.

Returns

0 on success

SM callback if set

uStatesSetState()

unsigned char uStatesSetState

(

unsigned int

state_id

)

Sets the next state of the state machine using the state's ID.

To change state in the state machine you must set the next state's ID which will then be handled during the next call to states_run. This will ensure the the current state's exit function is called before the next state's enter function is called.

Parameters

state_id

ID of the state that is to be run next

Returns

0 on success

vStatesClearInput()

void vStatesClearInput

(

void

)

Clears the 8 bit input vector stored in the state machine.

vStatesSetCallback()

void vStatesSetCallback

(

void(*)(void)

callback

)

Sets the callback function for the state machine.

The callback function is run at the end of each cycle of th state machine, the cycle being called using states_run.

Parameters

callback

A function pointer to the function that is to be called

vStatesSetData()

void vStatesSetData

(

void *

data

)

Sets the data of the current state.

Parameters

data	A void pointer to the data structure that is to be stored in the current state

vStatesSetInput()

void vStatesSetInput

(

unsigned char

input

)

Sets the input variable stored in the state machine.

The input variable of the state machine is a buffer to hold input that can be set from within the input function (interupts, polling, etc.)

Parameters

input

8 bit input vector

xStatesAdd()

int xStatesAdd	(	void(*)(void)	probe,
		void(*)(void)	enter,
		void(*)(void)	run,
		void(*)(void)	exit,
		int	ID,
		char *	name
	)

Adds a state to the state machine.

Parameters

probe	A function pointer to the state's init function
enter	A function pointer to the state's enter function
run	A function pointer to the state's run function
exit	A function pointer to the state's exit function
ID	The state's unique ID number
name	A string representation of the state's name

Returns

0 on success

xStatesDecrementState()

int xStatesDecrementState

(

void

)

Decrements the state to the previous in the linked list of states.

Returns

0 on success

xStatesGetStateCount()

int xStatesGetStateCount

(

void

)

Returns the number of states currently stored within the state machine.

Returns

unsigned int count of the number of states in the state machine

xStatesGetStateID()

int xStatesGetStateID

(

void

)

Returns the ID of the current state.

Returns

unsigned int ID

xStatesIncrementState()

int xStatesIncrementState

(

void

)

Increments the state to the next in the linked list of states.

Returns

0 on success