SC16IS7xxBuffer Class Reference

Class used internally for buffering data. More...

#include <SC16IS7xxRK.h>

Public Member Functions
	SC16IS7xxBuffer ()
	Construct a buffer object. You will normally never have to instantiate one.
virtual	~SC16IS7xxBuffer ()
	Destructor. You should never need to delete one.
bool	init (size_t bufSize)
	Allocate the buffer.
size_t	availableToRead () const
	Return the number of bytes that can be read from the buffer.
int	read ()
	Read a single byte.
int	read (uint8_t *buffer, size_t size)
	Read multiple bytes of data to a buffer.
size_t	availableToWrite () const
	The number of bytes available to write into the buffer.
size_t	write (const uint8_t *buffer, size_t size)
	Write data to the buffer.
void	writeCallback (std::function< void(uint8_t *buffer, size_t &size)> callback)
	Write data into buffer using a non-copy callback.
void	lock () const
	Lock the buffer mutex.
bool	trylock () const
	Attempt to lock the mutex. If already locked from another thread, returns false.
bool	try_lock () const
	Attempt to lock the mutex. If already locked from another thread, returns false.
void	unlock () const
	Unlock the buffer mutex.

Protected Member Functions
	SC16IS7xxBuffer (const SC16IS7xxBuffer &)=delete
	This class is not copyable.
SC16IS7xxBuffer &	operator= (const SC16IS7xxBuffer &)=delete
	This class is not copyable.
void	free ()
	Free the allocate buffer buf - used internally.

Protected Attributes
uint8_t *	buf = nullptr
	Buffer, allocated on heap.
size_t	bufSize = 0
	Size of buffer in bytes.
size_t	readOffset = 0
	Where to read from next, may be larger than bufSize.
size_t	writeOffset = 0
	Where to write to next, may be larger than bufSize.
RecursiveMutex	mutex
	Mutex to use to access buf, readOffset, or writeOffset.

Detailed Description

Class used internally for buffering data.

Since the hardware FIFO is only 64 bytes, this class is used to store data in a larger buffer allocated on the heap.

You do not create one of these objects; it's created automatically when using withBufferedRead().

Member Function Documentation

availableToRead()

size_t SC16IS7xxBuffer::availableToRead

(

)

const

Return the number of bytes that can be read from the buffer.

Returns

size_t Number of bytes that can be read. 0 = no data can be read now

availableToWrite()

size_t SC16IS7xxBuffer::availableToWrite

(

)

const

The number of bytes available to write into the buffer.

Returns

size_t Number of bytes that can be written

init()

bool SC16IS7xxBuffer::init

(

size_t

bufSize

)

Allocate the buffer.

Parameters

bufSize

Size of the buffer in bytes

Returns

true The buffer was allocated

false The buffer could not be allocated, typically out of heap space, or no contiguous block available

This is called from withBufferedRead(),

lock()

void SC16IS7xxBuffer::lock ( ) const

inline

Lock the buffer mutex.

A recursive mutex is used to protect access to buf, readOffset, and writeOffset since they can be accessed from two different threads. The buffer is written from the worker thread and read from whatever thread the user is reading from, typically the application loop thread.

read() [1/2]

int SC16IS7xxBuffer::read

(

)

Read a single byte.

Returns

int The byte value (0 - 255) or -1 if there is no data available to read.

read() [2/2]

int SC16IS7xxBuffer::read	(	uint8_t *	buffer,
		size_t	size
	)

Read multiple bytes of data to a buffer.

Parameters

buffer	The buffer to store data into
size	The number of bytes requested

Returns

int The number of bytes actually read.

The read() call does not block. It will only return the number of bytes currently available to read, so the number of bytes read will often be smaller than the requested number of bytes in size. The returned data is not null terminated.

try_lock()

bool SC16IS7xxBuffer::try_lock ( ) const

inline

Attempt to lock the mutex. If already locked from another thread, returns false.

Returns

true

false

trylock()

bool SC16IS7xxBuffer::trylock ( ) const

inline

Attempt to lock the mutex. If already locked from another thread, returns false.

Returns

true

false

write()

size_t SC16IS7xxBuffer::write	(	const uint8_t *	buffer,
		size_t	size
	)

Write data to the buffer.

Parameters

buffer
size

Returns

size_t The number of bytes written

This call does not block until there is space in the buffer! If there is insufficient space, only the bytes that will fit are stored and the return value indicates the amount the was stored.

writeCallback()

void SC16IS7xxBuffer::writeCallback

(

std::function< void(uint8_t *buffer, size_t &size)>

callback

)

Write data into buffer using a non-copy callback.

Parameters

callback

Function or C++ lambda, see below

This is used internally from the worker thread after reading a block of data from the UART by I2C or SPI. There is no single-byte write because that is never done because it would be extraordinarily inefficient.

Callback prototype: void(uint8_t *buffer, size_t &size)

If there is room in the buffer to write data, your callback is called during the execution of writeCallback. It's passed a buffer you should write data to and a size which is the maximum number of bytes you can write.

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

• src/SC16IS7xxRK.h
• src/SC16IS7xxRK.cpp