Piduino::IoMap

Memory mapping. More...

#include <iomap.h>

Collaboration diagram for Piduino::IoMap:

Public Member Functions
	IoMap ()
	Constructor.
virtual	~IoMap ()
	Destructor.
bool	open (const char *device, size_t size, off_t base=0)
bool	open (off_t base, size_t size)
	Open a memory mapping on /dev/mem.
bool	openGpioMem (int gpio_bank, size_t size)
	Open a GPIO memory mapping for RP1.
void	close ()
	Close a memory mapping.
volatile uint32_t *	io (size_t offset=0) const
	Pointer to access registers.
volatile uint32_t *	operator[] (size_t offset) const
	Pointer to access registers.
uint32_t	read (size_t offset) const
	Read a register.
void	write (size_t offset, uint32_t value)
	Write a value to a register.
uint32_t	atomicRead (size_t offset) const
	Atomic read of a register.
void	atomicWrite (size_t offset, uint32_t value)
	Atomic write to a register.
bool	isOpen () const
	Indicates if a memory mapping is open.
off_t	base () const
	Base address of the mapped area.
size_t	size () const
	Size of the mapped area.

Static Public Member Functions
static size_t	pageSize ()
	Size of a mapping page.

Private Attributes
off_t	_base
size_t	_size
int	_fd
void *	_map

Detailed Description

Memory mapping.

Definition at line 34 of file iomap.h.

Constructor & Destructor Documentation

IoMap()

Piduino::IoMap::IoMap

(

)

Constructor.

~IoMap()

virtual Piduino::IoMap::~IoMap ( )

virtual

Destructor.

Member Function Documentation

atomicRead()

uint32_t Piduino::IoMap::atomicRead ( size_t  offset ) const

inline

Atomic read of a register.

Parameters

offset

offset inside the area in sizeof(int)

Returns

the value read

This function reads a register atomically, ensuring that the read operation is not interrupted by other threads or processes.

Definition at line 122 of file iomap.h.

References io().

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atomicWrite()

void Piduino::IoMap::atomicWrite ( size_t  offset, uint32_t  value  )

inline

Atomic write to a register.

Parameters

offset	offset inside the area in sizeof(int)
value	value to write

This function writes a value to a register atomically, ensuring that the write operation is not interrupted by other threads or processes. It uses C11 atomic operations to ensure memory consistency.

Note

This function is useful for ensuring that hardware registers are updated safely in a multi-threaded environment.

Definition at line 137 of file iomap.h.

References io().

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base()

off_t Piduino::IoMap::base ( ) const

inline

Base address of the mapped area.

Definition at line 153 of file iomap.h.

References _base.

close()

void Piduino::IoMap::close

(

)

Close a memory mapping.

io()

volatile uint32_t * Piduino::IoMap::io ( size_t  offset = 0 ) const

inline

Pointer to access registers.

Parameters

offset

offset inside the area in sizeof(int)

Returns

pointer to the register, NULL if error

Definition at line 78 of file iomap.h.

References _map.

Referenced by atomicRead(), atomicWrite(), operator[](), read(), and write().

isOpen()

bool Piduino::IoMap::isOpen ( ) const

inline

Indicates if a memory mapping is open.

Definition at line 145 of file iomap.h.

References _fd.

open() [1/2]

bool Piduino::IoMap::open	(	const char *	device,
		size_t	size,
		off_t	base = 0
	)

open() [2/2]

bool Piduino::IoMap::open	(	off_t	base,
		size_t	size
	)

Open a memory mapping on /dev/mem.

Parameters

base	base address of the area to be mapped, must be a multiple of pageSize().
size	size of the area to be mapped in bytes

Returns

true if opened, false if error

openGpioMem()

bool Piduino::IoMap::openGpioMem	(	int	gpio_bank,
		size_t	size
	)

Open a GPIO memory mapping for RP1.

Parameters

gpio_bank	GPIO bank (0-4 for /dev/gpiomem0 to /dev/gpiomem4)
size	size of the area to be mapped in bytes

Returns

true if opened, false if error

Exceptions

std::system_error

if the open the device or memory mapping fails.

operator[]()

volatile uint32_t * Piduino::IoMap::operator[] ( size_t  offset ) const

inline

Pointer to access registers.

Parameters

offset

offset inside the area in sizeof(int)

Returns

pointer to the register, NULL if error

Definition at line 88 of file iomap.h.

References io().

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pageSize()

static size_t Piduino::IoMap::pageSize ( )

static

Size of a mapping page.

read()

uint32_t Piduino::IoMap::read ( size_t  offset ) const

inline

Read a register.

Parameters

offset

offset inside the area in sizeof(int)

Returns

the value read

This function reads a register at the specified offset and returns its value. It is a convenience method that allows direct access to the memory-mapped registers.

Definition at line 101 of file iomap.h.

References io().

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size()

size_t Piduino::IoMap::size ( ) const

inline

Size of the mapped area.

Definition at line 160 of file iomap.h.

References _size.

write()

void Piduino::IoMap::write ( size_t  offset, uint32_t  value  )

inline

Write a value to a register.

Parameters

offset	offset inside the area in sizeof(int)
value	value to write

Definition at line 110 of file iomap.h.

References io().

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Member Data Documentation

_base

off_t Piduino::IoMap::_base

private

Definition at line 170 of file iomap.h.

Referenced by base().

_fd

int Piduino::IoMap::_fd

private

Definition at line 172 of file iomap.h.

Referenced by isOpen().

_map

void* Piduino::IoMap::_map

private

Definition at line 173 of file iomap.h.

Referenced by io().

_size

size_t Piduino::IoMap::_size

private

Definition at line 171 of file iomap.h.

Referenced by size().