Device driver for decoding a DCC signal using a Timer resource. More...

#include <DccDecoder.hxx>

Inheritance diagram for DccDecoder< Module >:

Public Member Functions
	DccDecoder (const char name, RailcomDriver railcom_driver)
	Constructor.

void	set_packet_processor (dcc::PacketProcessor *p)
	Installs a hook that will be called in the interrupt context for each incoming packet.

void	interrupt_handler ()
	Handles a raw interrupt.

void	rcom_interrupt_handler ()
	Handles interrupt from the second timer used for railcom timing.

void	os_interrupt_handler ()
	Handles a software interrupt to FreeRTOS.

Public Member Functions inherited from Device
	Device (const char *name)
	Constructor.

virtual	~Device ()
	Destructor.

Private Types
typedef DCCPacket	input_data_type

Private Member Functions
ssize_t	read (File file, void buf, size_t count) OVERRIDE
	Read from a file or device.

ssize_t	write (File file, const void buf, size_t count) OVERRIDE
	Write to a file or device.

bool	select (File *file, int mode) OVERRIDE
	Device select method.

void	enable () override
	function to enable device

void	disable () override
	function to disable device

void	flush_buffers () override
	Discards all pending buffers.

	DISALLOW_COPY_AND_ASSIGN (DccDecoder)

Private Attributes
DeviceBuffer< DCCPacket > *	inputData_

bool	nextPacketFilled_ {false}

uint32_t	lastTimerValue_
	Holds the value of the free running timer at the time we captured the previous edge.

uint32_t	nextSample_
	Holds the timer value when we should be taking an occupancy sample the next time.

bool	sampleActive_ = false
	true if the next edge we shall sample.

unsigned	lastLevel_
	Seems unused?

bool	waitSampleForOverflow_ = false
	if true then sampling will be suspended until the timer overflows.

bool	inCutout_ = false
	True if the current internal state is the cutout state.

bool	prepCutout_ = false
	True for the last bit time before the cutout, to prevent sampling fro colliding with cutout.

uint32_t	cutoutState_
	Which window of the cutout we are in.

uint32_t	packetId_ = 0
	Counts unique identifiers for DCC packets to be returned.

RailcomDriver *	railcomDriver_
	How many times did we lose a DCC packet due to no buffer available.

dcc::PacketProcessor *	packetProcessor_ = nullptr
	notified for every arrived DCC / MM packet within the interrupt.

dcc::DccDecoder	decoder_ {Module::get_ticks_per_usec()}
	DCC packet decoder state machine and internal state.

Static Private Attributes
static const auto	RAILCOM_CUTOUT_PRE = 26
	How many usec the railcom has before the cutout (measured from the packet end 1 bit complete)

static const auto	RAILCOM_CUTOUT_MID = 185
	How many usec the railcom has to the middle of window (measured from the packet end 1 bit complete)

static const auto	RAILCOM_CUTOUT_END = 471
	How many usec the railcom has to the end of the window (measured from the packet end 1 bit complete)

Additional Inherited Members
Static Public Member Functions inherited from Device
static int	open (struct _reent reent, const char path, int flags, int mode)
	Open a file or device.

static int	close (struct _reent *reent, int fd)
	Close a file or device.

static int	stat (struct _reent reent, const char path, struct stat *stat)
	Get the status information of a file or device.

static int	select (int nfds, fd_set readfds, fd_set writefds, fd_set *exceptfds, long long timeout)
	POSIX select().

static void	select_clear ()
	Clears the current thread's select bits.

Static Public Member Functions inherited from FileIO
static ssize_t	read (struct _reent reent, int fd, void buf, size_t count)
	Read from a file or device.

static ssize_t	write (struct _reent reent, int fd, const void buf, size_t count)
	Write to a file or device.

static _off_t	lseek (struct _reent *reent, int fd, _off_t offset, int whence)
	Change the offset index of a file or device.

static int	fstat (struct _reent reent, int fd, struct stat stat)
	Get the status information of a file or device.

static int	ioctl (int fd, unsigned long int key, unsigned long data)
	Request and ioctl transaction.

static int	fcntl (int fd, int cmd, unsigned long data)
	Manipulate a file descriptor.

static bool	is_device (int fd)
	Test if the file descriptor belongs to a device.

Protected Member Functions inherited from Node
	Node (const char *name)
	Constructor.

virtual	~Node ()
	Destructor.

int	open (File , const char , int, int) OVERRIDE
	Open method.

int	close (File *) OVERRIDE
	Close method.

virtual int	fstat (File file, struct stat stat) override
	Get the status information of a file or device.

Protected Member Functions inherited from FileIO
	FileIO (const char *name)
	Constructor.

virtual	~FileIO ()
	Destructor.

virtual off_t	lseek (File *f, off_t offset, int whence)
	Seek method.

virtual int	ioctl (File *file, unsigned long int key, unsigned long data)
	Request an ioctl transaction.

virtual int	fcntl (File *file, int cmd, unsigned long data)
	Manipulate a file descriptor.

Static Protected Member Functions inherited from Device
static void	select_insert (SelectInfo *info)
	Add client to list of clients needing woken.

static void	select_wakeup (SelectInfo *info)
	Wakeup the list of clients needing woken.

static void	select_wakeup_from_isr (SelectInfo info, int woken)
	Wakeup the list of clients needing woken.

Static Protected Member Functions inherited from FileIO
static int	fd_alloc (void)
	Allocate a free file descriptor.

static void	fd_free (int fd)
	Free up a file descriptor.

static File *	file_lookup (int fd)
	Looks up a reference to a File corresponding to a given file descriptor.

static int	fd_lookup (File *file)
	Looks up a file descriptor corresponding to a given File reference.

Protected Attributes inherited from Node
OSMutex	lock_
	protects internal structures.

mode_t	mode_
	File open mode, such as O_NONBLOCK.

unsigned int	references_
	number of open references

Protected Attributes inherited from FileIO
const char *	name
	device name

Static Protected Attributes inherited from FileIO
static const unsigned int	numOpenFiles = 20

static File	files []
	File descriptor pool.

static OSMutex	mutex
	mutual exclusion for fileio

Detailed Description

template<class Module>
class DccDecoder< Module >

Device driver for decoding a DCC signal using a Timer resource.

This driver exports a filesystem device node, which will be readable for decoded DCC packets (read into struct DCCPacket). All writes fail.

The additional feature supported by this device driver is that it is able to tell a RailcomDriver when the railcom cutout is supposed to start, when we're in the middle and when it is over. This is necessary for the correct functionality of the railcom driver.

Usage:

Define a module for accessing the timer. See the following two examples: {} { Stm32DccTimerModule }. In the HwInit.cxx, instantiate the driver with passing the module as a template argument. The above example modules themselves take a template argument with static definitions. Module API:NRZ_PinTIMER_MAX_VALUESAMPLE_PERIOD_CLOCKSQ_SIZETICKS_PER_USECmodule_init()module_enable()module_disable()trigger_os_interrupt()dcc_before_cutout_hook()dcc_packet_finished_hook()after_feedback_hook()int_get_and_clear_capture_event()get_capture_counter()int_get_and_clear_delay_event()set_cap_timer_capture()set_cap_timer_time()set_cap_timer_delay_usec()stop_cap_timer_time()

Definition at line 84 of file DccDecoder.hxx.

Member Typedef Documentation

◆ input_data_type

template<class Module >

typedef DCCPacket DccDecoder< Module >::input_data_type

private

Definition at line 205 of file DccDecoder.hxx.

Constructor & Destructor Documentation

◆ DccDecoder()

template<class Module >

DccDecoder< Module >::DccDecoder	(	const char *	name,
		RailcomDriver *	railcom_driver
	)

Constructor.

Parameters

name	name of device node, e.g. "/dev/dccdecode0"
railcom_driver	is the associated railcom driver, which will get the callbacks from the timing of the acquired signal.

Definition at line 256 of file DccDecoder.hxx.

◆ ~DccDecoder()

template<class Module >

DccDecoder< Module >::~DccDecoder ( )

inline

Definition at line 94 of file DccDecoder.hxx.

Member Function Documentation

◆ disable()

template<class Module >

void DccDecoder< Module >::disable ( )

overrideprivatevirtual

function to disable device

Implements Node.

Definition at line 283 of file DccDecoder.hxx.

◆ enable()

template<class Module >

void DccDecoder< Module >::enable ( )

overrideprivatevirtual

function to enable device

Implements Node.

Definition at line 265 of file DccDecoder.hxx.

◆ flush_buffers()

template<class Module >

void DccDecoder< Module >::flush_buffers ( )

inlineoverrideprivatevirtual

Discards all pending buffers.

Called after disable().

Implements Node.

Definition at line 196 of file DccDecoder.hxx.

◆ interrupt_handler()

template<class Module >

void DccDecoder< Module >::interrupt_handler ( )

inline

Handles a raw interrupt.

Definition at line 289 of file DccDecoder.hxx.

◆ os_interrupt_handler()

template<class Module >

void DccDecoder< Module >::os_interrupt_handler ( )

inline

Handles a software interrupt to FreeRTOS.

Definition at line 429 of file DccDecoder.hxx.

◆ rcom_interrupt_handler()

template<class Module >

void DccDecoder< Module >::rcom_interrupt_handler ( )

inline

Handles interrupt from the second timer used for railcom timing.

Definition at line 391 of file DccDecoder.hxx.

◆ read()

template<class Module >

ssize_t DccDecoder< Module >::read	(	File *	file,
		void *	buf,
		size_t	count
	)

inlineprivatevirtual

Read from a file or device.

Parameters

file	file reference for this device
buf	location to place read data
count	number of bytes to read

Returns: number of bytes read upon success, -1 upon failure with errno containing the cause

Implements FileIO.

Definition at line 124 of file DccDecoder.hxx.

◆ select()

template<class Module >

bool DccDecoder< Module >::select	(	File *	file,
		int	mode
	)

inlineprivatevirtual

Device select method.

Default impementation returns true.

Parameters

file	reference to the file
mode	FREAD for read active, FWRITE for write active, 0 for exceptions

Returns: true if active, false if inactive

Reimplemented from FileIO.

Definition at line 168 of file DccDecoder.hxx.

◆ set_packet_processor()

template<class Module >

void DccDecoder< Module >::set_packet_processor ( dcc::PacketProcessor * p )

inline

Installs a hook that will be called in the interrupt context for each incoming packet.

Parameters

p	the hook interface to be called.

Definition at line 102 of file DccDecoder.hxx.

◆ write()

template<class Module >

ssize_t DccDecoder< Module >::write	(	File *	file,
		const void *	buf,
		size_t	count
	)

inlineprivatevirtual

Write to a file or device.

Parameters

file	file reference for this device
buf	location to find write data
count	number of bytes to write

Returns: number of bytes written upon success, -1 upon failure with errno containing the cause

Implements FileIO.

Definition at line 157 of file DccDecoder.hxx.

Member Data Documentation

◆ cutoutState_

template<class Module >

uint32_t DccDecoder< Module >::cutoutState_

private

Which window of the cutout we are in.

Definition at line 227 of file DccDecoder.hxx.

◆ decoder_

template<class Module >

dcc::DccDecoder DccDecoder< Module >::decoder_ {Module::get_ticks_per_usec()}

private

DCC packet decoder state machine and internal state.

Definition at line 240 of file DccDecoder.hxx.

◆ inCutout_

template<class Module >

bool DccDecoder< Module >::inCutout_ = false

private

True if the current internal state is the cutout state.

Definition at line 222 of file DccDecoder.hxx.

◆ inputData_

template<class Module >

DeviceBuffer<DCCPacket>* DccDecoder< Module >::inputData_

private

Initial value:

{

DeviceBuffer<DCCPacket>::create(Module::Q_SIZE)}

DeviceBuffer::create

static DeviceBuffer * create(size_t size, size_t level=0)

Create a DeviceBuffer instance.

Definition DeviceBuffer.hxx:224

Definition at line 206 of file DccDecoder.hxx.

◆ lastLevel_

template<class Module >

unsigned DccDecoder< Module >::lastLevel_

private

Seems unused?

Todo:: delete.

Definition at line 218 of file DccDecoder.hxx.

◆ lastTimerValue_

template<class Module >

uint32_t DccDecoder< Module >::lastTimerValue_

private

Holds the value of the free running timer at the time we captured the previous edge.

Definition at line 211 of file DccDecoder.hxx.

◆ nextPacketFilled_

template<class Module >

bool DccDecoder< Module >::nextPacketFilled_ {false}

private

Definition at line 208 of file DccDecoder.hxx.

◆ nextSample_

template<class Module >

uint32_t DccDecoder< Module >::nextSample_

private

Holds the timer value when we should be taking an occupancy sample the next time.

Definition at line 214 of file DccDecoder.hxx.

◆ packetId_

template<class Module >

uint32_t DccDecoder< Module >::packetId_ = 0

private

Counts unique identifiers for DCC packets to be returned.

Definition at line 229 of file DccDecoder.hxx.

◆ packetProcessor_

template<class Module >

dcc::PacketProcessor* DccDecoder< Module >::packetProcessor_ = nullptr

private

notified for every arrived DCC / MM packet within the interrupt.

Definition at line 237 of file DccDecoder.hxx.

◆ prepCutout_

template<class Module >

bool DccDecoder< Module >::prepCutout_ = false

private

True for the last bit time before the cutout, to prevent sampling fro colliding with cutout.

Definition at line 225 of file DccDecoder.hxx.

◆ RAILCOM_CUTOUT_END

template<class Module >

const auto DccDecoder< Module >::RAILCOM_CUTOUT_END = 471

staticprivate

How many usec the railcom has to the end of the window (measured from the packet end 1 bit complete)

Definition at line 250 of file DccDecoder.hxx.

◆ RAILCOM_CUTOUT_MID

template<class Module >

const auto DccDecoder< Module >::RAILCOM_CUTOUT_MID = 185

staticprivate

How many usec the railcom has to the middle of window (measured from the packet end 1 bit complete)

Definition at line 247 of file DccDecoder.hxx.

◆ RAILCOM_CUTOUT_PRE

template<class Module >

const auto DccDecoder< Module >::RAILCOM_CUTOUT_PRE = 26

staticprivate

How many usec the railcom has before the cutout (measured from the packet end 1 bit complete)

Definition at line 244 of file DccDecoder.hxx.

◆ railcomDriver_

template<class Module >

RailcomDriver* DccDecoder< Module >::railcomDriver_

private

How many times did we lose a DCC packet due to no buffer available.

notified for cutout events.

Definition at line 234 of file DccDecoder.hxx.

◆ sampleActive_

template<class Module >

bool DccDecoder< Module >::sampleActive_ = false

private

true if the next edge we shall sample.

Definition at line 216 of file DccDecoder.hxx.

◆ waitSampleForOverflow_

template<class Module >

bool DccDecoder< Module >::waitSampleForOverflow_ = false

private

if true then sampling will be suspended until the timer overflows.

Definition at line 220 of file DccDecoder.hxx.

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

DccDecoder.hxx

Public Member Functions

Private Types

Private Member Functions

Private Attributes

Static Private Attributes

Additional Inherited Members

Detailed Description

Member Typedef Documentation

◆ input_data_type

Constructor & Destructor Documentation

◆ DccDecoder()

◆ ~DccDecoder()

Member Function Documentation

◆ disable()

◆ enable()

◆ flush_buffers()

◆ interrupt_handler()

◆ os_interrupt_handler()

◆ rcom_interrupt_handler()

◆ read()

◆ select()

◆ set_packet_processor()

◆ write()

Member Data Documentation

◆ cutoutState_

◆ decoder_

◆ inCutout_

◆ inputData_

◆ lastLevel_

◆ lastTimerValue_

◆ nextPacketFilled_

◆ nextSample_

◆ packetId_

◆ packetProcessor_

◆ prepCutout_

◆ RAILCOM_CUTOUT_END

◆ RAILCOM_CUTOUT_MID

◆ RAILCOM_CUTOUT_PRE

◆ railcomDriver_

◆ sampleActive_

◆ waitSampleForOverflow_