Channel

Data Structures
struct	iio_channel
	Represents an input or output channel of a device. More...
Functions
__api __pure struct iio_device *	iio_channel_get_device (const struct iio_channel *chn)
	Retrieve a pointer to the iio_device structure.
__api __pure const char *	iio_channel_get_id (const struct iio_channel *chn)
	Retrieve the channel ID (e.g. voltage0)
__api __pure const char *	iio_channel_get_name (const struct iio_channel *chn)
	Retrieve the channel name (e.g. vccint)
__api __pure bool	iio_channel_is_output (const struct iio_channel *chn)
	Return True if the given channel is an output channel.
__api __pure bool	iio_channel_is_scan_element (const struct iio_channel *chn)
	Return True if the given channel is a scan element.
__api __pure unsigned int	iio_channel_get_attrs_count (const struct iio_channel *chn)
	Enumerate the channel-specific attributes of the given channel.
__api __pure const char *	iio_channel_get_attr (const struct iio_channel *chn, unsigned int index)
	Get the channel-specific attribute present at the given index.
__api __pure const char *	iio_channel_find_attr (const struct iio_channel *chn, const char *name)
	Try to find a channel-specific attribute by its name.
__api __pure const char *	iio_channel_attr_get_filename (const struct iio_channel *chn, const char *attr)
	Retrieve the filename of an attribute.
__api ssize_t	iio_channel_attr_read (const struct iio_channel *chn, const char *attr, char *dst, size_t len)
	Read the content of the given channel-specific attribute.
__api int	iio_channel_attr_read_all (struct iio_channel *chn, int(*cb)(struct iio_channel *chn, const char *attr, const char *val, size_t len, void *d), void *data)
	Read the content of all channel-specific attributes.
__api int	iio_channel_attr_read_bool (const struct iio_channel *chn, const char *attr, bool *val)
	Read the content of the given channel-specific attribute.
__api int	iio_channel_attr_read_longlong (const struct iio_channel *chn, const char *attr, long long *val)
	Read the content of the given channel-specific attribute.
__api int	iio_channel_attr_read_double (const struct iio_channel *chn, const char *attr, double *val)
	Read the content of the given channel-specific attribute.
__api ssize_t	iio_channel_attr_write (const struct iio_channel *chn, const char *attr, const char *src)
	Set the value of the given channel-specific attribute.
__api ssize_t	iio_channel_attr_write_raw (const struct iio_channel *chn, const char *attr, const void *src, size_t len)
	Set the value of the given channel-specific attribute.
__api int	iio_channel_attr_write_all (struct iio_channel *chn, ssize_t(*cb)(struct iio_channel *chn, const char *attr, void *buf, size_t len, void *d), void *data)
	Set the values of all channel-specific attributes.
__api int	iio_channel_attr_write_bool (const struct iio_channel *chn, const char *attr, bool val)
	Set the value of the given channel-specific attribute.
__api int	iio_channel_attr_write_longlong (const struct iio_channel *chn, const char *attr, long long val)
	Set the value of the given channel-specific attribute.
__api int	iio_channel_attr_write_double (const struct iio_channel *chn, const char *attr, double val)
	Set the value of the given channel-specific attribute.
__api void	iio_channel_enable (struct iio_channel *chn)
	Enable the given channel.
__api void	iio_channel_disable (struct iio_channel *chn)
	Disable the given channel.
__api bool	iio_channel_is_enabled (const struct iio_channel *chn)
	Returns True if the channel is enabled.
__api size_t	iio_channel_read_raw (const struct iio_channel *chn, struct iio_buffer *buffer, void *dst, size_t len)
__api size_t	iio_channel_read (const struct iio_channel *chn, struct iio_buffer *buffer, void *dst, size_t len)
__api size_t	iio_channel_write_raw (const struct iio_channel *chn, struct iio_buffer *buffer, const void *src, size_t len)
__api size_t	iio_channel_write (const struct iio_channel *chn, struct iio_buffer *buffer, const void *src, size_t len)
__api void	iio_channel_set_data (struct iio_channel *chn, void *data)
	Associate a pointer to an iio_channel structure.
__api void *	iio_channel_get_data (const struct iio_channel *chn)
	Retrieve a previously associated pointer of an iio_channel structure.
__api __pure enum iio_chan_type	iio_channel_get_type (const struct iio_channel *chn)
	Get the type of the given channel.
__api __pure enum iio_modifier	iio_channel_get_modifier (const struct iio_channel *chn)
	Get the modifier type of the given channel.

---

Function Documentation

__api __pure const char* iio_channel_attr_get_filename	(	const struct iio_channel *	chn,
		const char *	attr
	)

Retrieve the filename of an attribute.

Parameters:

chn	A pointer to an iio_channel structure
attr	a NULL-terminated string corresponding to the name of the attribute

Returns:

On success, a pointer to a static NULL-terminated string

If the attribute name is unknown, NULL is returned

__api ssize_t iio_channel_attr_read	(	const struct iio_channel *	chn,
		const char *	attr,
		char *	dst,
		size_t	len
	)

Read the content of the given channel-specific attribute.

Parameters:

chn	A pointer to an iio_channel structure
attr	A NULL-terminated string corresponding to the name of the attribute
dst	A pointer to the memory area where the NULL-terminated string corresponding to the value read will be stored
len	The available length of the memory area, in bytes

Returns:

On success, the number of bytes written to the buffer

On error, a negative errno code is returned

NOTE:By passing NULL as the "attr" argument to iio_channel_attr_read, it is now possible to read all of the attributes of a channel.

The buffer is filled with one block of data per attribute of the channel, by the order they appear in the iio_channel structure.

The first four bytes of one block correspond to a 32-bit signed value in network order. If negative, it corresponds to the errno code that were returned when reading the attribute; if positive, it corresponds to the length of the data read. In that case, the rest of the block contains the data.

__api int iio_channel_attr_read_all	(	struct iio_channel *	chn,
		int(*)(struct iio_channel *chn, const char *attr, const char *val, size_t len, void *d)	cb,
		void *	data
	)

Read the content of all channel-specific attributes.

Parameters:

chn	A pointer to an iio_channel structure
cb	A pointer to a callback function
data	A pointer that will be passed to the callback function

Returns:

On success, 0 is returned

On error, a negative errno code is returned

NOTE: This function is especially useful when used with the network backend, as all the channel-specific attributes are read in one single command.

__api int iio_channel_attr_read_bool	(	const struct iio_channel *	chn,
		const char *	attr,
		bool *	val
	)

Read the content of the given channel-specific attribute.

Parameters:

chn	A pointer to an iio_channel structure
attr	A NULL-terminated string corresponding to the name of the attribute
val	A pointer to a bool variable where the value should be stored

Returns:

On success, 0 is returned

On error, a negative errno code is returned

__api int iio_channel_attr_read_double	(	const struct iio_channel *	chn,
		const char *	attr,
		double *	val
	)

Read the content of the given channel-specific attribute.

Parameters:

chn	A pointer to an iio_channel structure
attr	A NULL-terminated string corresponding to the name of the attribute
val	A pointer to a double variable where the value should be stored

Returns:

On success, 0 is returned

On error, a negative errno code is returned

__api int iio_channel_attr_read_longlong	(	const struct iio_channel *	chn,
		const char *	attr,
		long long *	val
	)

Read the content of the given channel-specific attribute.

Parameters:

chn	A pointer to an iio_channel structure
attr	A NULL-terminated string corresponding to the name of the attribute
val	A pointer to a long long variable where the value should be stored

Returns:

On success, 0 is returned

On error, a negative errno code is returned

__api ssize_t iio_channel_attr_write	(	const struct iio_channel *	chn,
		const char *	attr,
		const char *	src
	)

Set the value of the given channel-specific attribute.

Parameters:

chn	A pointer to an iio_channel structure
attr	A NULL-terminated string corresponding to the name of the attribute
src	A NULL-terminated string to set the attribute to

Returns:

On success, the number of bytes written

On error, a negative errno code is returned

NOTE:By passing NULL as the "attr" argument to iio_channel_attr_write, it is now possible to write all of the attributes of a channel.

The buffer must contain one block of data per attribute of the channel, by the order they appear in the iio_channel structure.

The first four bytes of one block correspond to a 32-bit signed value in network order. If negative, the attribute is not written; if positive, it corresponds to the length of the data to write. In that case, the rest of the block must contain the data.

__api int iio_channel_attr_write_all	(	struct iio_channel *	chn,
		ssize_t(*)(struct iio_channel *chn, const char *attr, void *buf, size_t len, void *d)	cb,
		void *	data
	)

Set the values of all channel-specific attributes.

Parameters:

chn	A pointer to an iio_channel structure
cb	A pointer to a callback function
data	A pointer that will be passed to the callback function

Returns:

On success, 0 is returned

On error, a negative errno code is returned

NOTE: This function is especially useful when used with the network backend, as all the channel-specific attributes are written in one single command.

__api int iio_channel_attr_write_bool	(	const struct iio_channel *	chn,
		const char *	attr,
		bool	val
	)

Set the value of the given channel-specific attribute.

Parameters:

chn	A pointer to an iio_channel structure
attr	A NULL-terminated string corresponding to the name of the attribute
val	A bool value to set the attribute to

Returns:

On success, 0 is returned

On error, a negative errno code is returned

__api int iio_channel_attr_write_double	(	const struct iio_channel *	chn,
		const char *	attr,
		double	val
	)

Set the value of the given channel-specific attribute.

Parameters:

chn	A pointer to an iio_channel structure
attr	A NULL-terminated string corresponding to the name of the attribute
val	A double value to set the attribute to

Returns:

On success, 0 is returned

On error, a negative errno code is returned

__api int iio_channel_attr_write_longlong	(	const struct iio_channel *	chn,
		const char *	attr,
		long long	val
	)

Set the value of the given channel-specific attribute.

Parameters:

chn	A pointer to an iio_channel structure
attr	A NULL-terminated string corresponding to the name of the attribute
val	A long long value to set the attribute to

Returns:

On success, 0 is returned

On error, a negative errno code is returned

__api ssize_t iio_channel_attr_write_raw	(	const struct iio_channel *	chn,
		const char *	attr,
		const void *	src,
		size_t	len
	)

Set the value of the given channel-specific attribute.

Parameters:

chn	A pointer to an iio_channel structure
attr	A NULL-terminated string corresponding to the name of the attribute
src	A pointer to the data to be written
len	The number of bytes that should be written

Returns:

On success, the number of bytes written

On error, a negative errno code is returned

__api void iio_channel_disable

(

struct iio_channel *

chn

)

Disable the given channel.

Parameters:

chn	A pointer to an iio_channel structure

__api void iio_channel_enable

(

struct iio_channel *

chn

)

Enable the given channel.

Parameters:

chn	A pointer to an iio_channel structure

NOTE:Before creating an iio_buffer structure with iio_device_create_buffer, it is required to enable at least one channel of the device to read from.

__api __pure const char* iio_channel_find_attr	(	const struct iio_channel *	chn,
		const char *	name
	)

Try to find a channel-specific attribute by its name.

Parameters:

chn	A pointer to an iio_channel structure
name	A NULL-terminated string corresponding to the name of the attribute

Returns:

On success, a pointer to a static NULL-terminated string

If the name does not correspond to any known attribute of the given channel, NULL is returned

NOTE: This function is useful to detect the presence of an attribute. It can also be used to retrieve the name of an attribute as a pointer to a static string from a dynamically allocated string.

__api __pure const char* iio_channel_get_attr	(	const struct iio_channel *	chn,
		unsigned int	index
	)

Get the channel-specific attribute present at the given index.

Parameters:

chn	A pointer to an iio_channel structure
index	The index corresponding to the attribute

Returns:

On success, a pointer to a static NULL-terminated string

If the index is invalid, NULL is returned

__api __pure unsigned int iio_channel_get_attrs_count

(

const struct iio_channel *

chn

)

Enumerate the channel-specific attributes of the given channel.

Parameters:

chn	A pointer to an iio_channel structure

Returns:

The number of channel-specific attributes found

__api void* iio_channel_get_data

(

const struct iio_channel *

chn

)

Retrieve a previously associated pointer of an iio_channel structure.

Parameters:

chn	A pointer to an iio_channel structure

Returns:

The pointer previously associated if present, or NULL

__api __pure struct iio_device* iio_channel_get_device

(

const struct iio_channel *

chn

)

[read]

Retrieve a pointer to the iio_device structure.

Parameters:

chn	A pointer to an iio_channel structure

Returns:

A pointer to an iio_device structure

__api __pure const char* iio_channel_get_id

(

const struct iio_channel *

chn

)

Retrieve the channel ID (e.g. voltage0)

Parameters:

chn	A pointer to an iio_channel structure

Returns:

A pointer to a static NULL-terminated string

__api __pure enum iio_modifier iio_channel_get_modifier

(

const struct iio_channel *

chn

)

Get the modifier type of the given channel.

Parameters:

chn	A pointer to an iio_channel structure

Returns:

The modifier type of the channel

__api __pure const char* iio_channel_get_name

(

const struct iio_channel *

chn

)

Retrieve the channel name (e.g. vccint)

Parameters:

chn	A pointer to an iio_channel structure

Returns:

A pointer to a static NULL-terminated string

NOTE: if the channel has no name, NULL is returned.

__api __pure enum iio_chan_type iio_channel_get_type

(

const struct iio_channel *

chn

)

Get the type of the given channel.

Parameters:

chn	A pointer to an iio_channel structure

Returns:

The type of the channel

__api bool iio_channel_is_enabled

(

const struct iio_channel *

chn

)

Returns True if the channel is enabled.

Parameters:

chn	A pointer to an iio_channel structure

Returns:

True if the channel is enabled, False otherwise

__api __pure bool iio_channel_is_output

(

const struct iio_channel *

chn

)

Return True if the given channel is an output channel.

Parameters:

chn	A pointer to an iio_channel structure

Returns:

True if the channel is an output channel, False otherwise

__api __pure bool iio_channel_is_scan_element

(

const struct iio_channel *

chn

)

Return True if the given channel is a scan element.

Parameters:

chn	A pointer to an iio_channel structure

Returns:

True if the channel is a scan element, False otherwise

NOTE: a channel that is a scan element is a channel that can generate samples (for an input channel) or receive samples (for an output channel) after being enabled.

__api size_t iio_channel_read	(	const struct iio_channel *	chn,
		struct iio_buffer *	buffer,
		void *	dst,
		size_t	len
	)

Demultiplex and convert the samples of a given channel

Parameters:

chn	A pointer to an iio_channel structure
buffer	A pointer to an iio_buffer structure
dst	A pointer to the memory area where the converted data will be stored
len	The available length of the memory area, in bytes

Returns:

The size of the converted data, in bytes

__api size_t iio_channel_read_raw	(	const struct iio_channel *	chn,
		struct iio_buffer *	buffer,
		void *	dst,
		size_t	len
	)

Demultiplex the samples of a given channel

Parameters:

chn	A pointer to an iio_channel structure
buffer	A pointer to an iio_buffer structure
dst	A pointer to the memory area where the demultiplexed data will be stored
len	The available length of the memory area, in bytes

Returns:

The size of the demultiplexed data, in bytes

__api void iio_channel_set_data	(	struct iio_channel *	chn,
		void *	data
	)

Associate a pointer to an iio_channel structure.

Parameters:

chn	A pointer to an iio_channel structure
data	The pointer to be associated

__api size_t iio_channel_write	(	const struct iio_channel *	chn,
		struct iio_buffer *	buffer,
		const void *	src,
		size_t	len
	)

Convert and multiplex the samples of a given channel

Parameters:

chn	A pointer to an iio_channel structure
buffer	A pointer to an iio_buffer structure
src	A pointer to the memory area where the sequential data will be read from
len	The length of the memory area, in bytes

Returns:

The number of bytes actually converted and multiplexed

__api size_t iio_channel_write_raw	(	const struct iio_channel *	chn,
		struct iio_buffer *	buffer,
		const void *	src,
		size_t	len
	)

Multiplex the samples of a given channel

Parameters:

chn	A pointer to an iio_channel structure
buffer	A pointer to an iio_buffer structure
src	A pointer to the memory area where the sequential data will be read from
len	The length of the memory area, in bytes

Returns:

The number of bytes actually multiplexed