dcc::RailcomBroadcastDecoder Class Reference

Simple state machine to decode DCC address from railcom broadcast packets. More...

#include <RailcomBroadcastDecoder.hxx>

Public Member Functions
uint16_t	current_address ()
bool	process_packet (const dcc::Feedback &packet)
	Decodes a packet.
void	set_occupancy (bool value)
	Notifies the state machine about observed occupancy.

Public Attributes
uint16_t	lastAddress_
	usable by clients for storage.

Private Member Functions
bool	process_data (const uint8_t *data, unsigned size)
	Helper function to process a sequence of bytes (whichever window they are coming from).
void	notify_empty ()
	Notifies the state machine that there is no occupancy detected.

Private Attributes
uint8_t	currentH_
	last received high address bits
uint8_t	currentL_
	last received low address bits
uint8_t	countH_
	observed repeat count of high address bits
uint8_t	countL_
	observed repeat count of low address bits
uint16_t	currentAddress_
	last valid address (0 if no valid address)

Static Private Attributes
static const uint8_t	MIN_REPEAT_COUNT = 3
	How many times we shall get the same data out of railcom before we believe it and report to the bus.
static const uint8_t	MIN_EMPTY_COUNT = 8
	This is how many empty packets we need to forget the current address when we're getting empty packets.

Detailed Description

Simple state machine to decode DCC address from railcom broadcast packets.

Usage:

For each incoming Railcom packet call the process_packet() function. call the current_address() function to retrieve the currently known address that came with the global broadcast.

Definition at line 51 of file RailcomBroadcastDecoder.hxx.

Constructor & Destructor Documentation

RailcomBroadcastDecoder()

dcc::RailcomBroadcastDecoder::RailcomBroadcastDecoder ( )

inline

Definition at line 54 of file RailcomBroadcastDecoder.hxx.

Member Function Documentation

current_address()

uint16_t dcc::RailcomBroadcastDecoder::current_address ( )

inline

Returns

the currently valid DCC address, or zero if no valid address right now.

Definition at line 66 of file RailcomBroadcastDecoder.hxx.

notify_empty()

void dcc::RailcomBroadcastDecoder::notify_empty ( )

private

Notifies the state machine that there is no occupancy detected.

Definition at line 143 of file RailcomBroadcastDecoder.cxx.

process_data()

bool dcc::RailcomBroadcastDecoder::process_data ( const uint8_t *  data, unsigned  size  )

private

Helper function to process a sequence of bytes (whichever window they are coming from).

Parameters

data	pointer to bytes
size	how many bytes arethere to decode.

Returns

dunno.

TODO(balazs.racz) if we have only one byte in ch1 but we have a second byte in ch2, we should still process those because it might be a misaligned window.

Definition at line 66 of file RailcomBroadcastDecoder.cxx.

process_packet()

bool dcc::RailcomBroadcastDecoder::process_packet

(

const dcc::Feedback &

packet

)

Decodes a packet.

Parameters

packet

is what to decode.

Returns

true if the packet is garbage or matches a global address broadcast, false if it is a valid packet that is not an address broadcast.

true if the packet is garbage or matches a global address broadcast, false if it is a valid packet that is not an address broadcast.

Definition at line 47 of file RailcomBroadcastDecoder.cxx.

set_occupancy()

void dcc::RailcomBroadcastDecoder::set_occupancy

(

bool

value

)

Notifies the state machine about observed occupancy.

Parameters

value

is true if the track is sensed as occupied.

Definition at line 134 of file RailcomBroadcastDecoder.cxx.

Member Data Documentation

countH_

uint8_t dcc::RailcomBroadcastDecoder::countH_

private

observed repeat count of high address bits

Definition at line 101 of file RailcomBroadcastDecoder.hxx.

countL_

uint8_t dcc::RailcomBroadcastDecoder::countL_

private

observed repeat count of low address bits

Definition at line 102 of file RailcomBroadcastDecoder.hxx.

currentAddress_

uint16_t dcc::RailcomBroadcastDecoder::currentAddress_

private

last valid address (0 if no valid address)

Definition at line 104 of file RailcomBroadcastDecoder.hxx.

currentH_

uint8_t dcc::RailcomBroadcastDecoder::currentH_

private

last received high address bits

Definition at line 99 of file RailcomBroadcastDecoder.hxx.

currentL_

uint8_t dcc::RailcomBroadcastDecoder::currentL_

private

last received low address bits

Definition at line 100 of file RailcomBroadcastDecoder.hxx.

lastAddress_

uint16_t dcc::RailcomBroadcastDecoder::lastAddress_

usable by clients for storage.

Definition at line 108 of file RailcomBroadcastDecoder.hxx.

MIN_EMPTY_COUNT

const uint8_t dcc::RailcomBroadcastDecoder::MIN_EMPTY_COUNT = 8

staticprivate

This is how many empty packets we need to forget the current address when we're getting empty packets.

Definition at line 97 of file RailcomBroadcastDecoder.hxx.

MIN_REPEAT_COUNT

const uint8_t dcc::RailcomBroadcastDecoder::MIN_REPEAT_COUNT = 3

staticprivate

How many times we shall get the same data out of railcom before we believe it and report to the bus.

Definition at line 94 of file RailcomBroadcastDecoder.hxx.

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The documentation for this class was generated from the following files:

• RailcomBroadcastDecoder.hxx
• RailcomBroadcastDecoder.cxx