Buffer

Data Structures
struct	iio_buffer
	An input or output buffer, used to read or write samples. More...

Functions
__api struct iio_buffer *	iio_device_create_buffer (const struct iio_device *dev, size_t samples_count, bool cyclic)
	Create an input or output buffer associated to the given device. More...
__api void	iio_buffer_destroy (struct iio_buffer *buf)
	Destroy the given buffer. More...
__api ssize_t	iio_buffer_refill (struct iio_buffer *buf)
	Fetch more samples from the hardware. More...
__api ssize_t	iio_buffer_push (struct iio_buffer *buf)
	Send the samples to the hardware. More...
__api void *	iio_buffer_start (const struct iio_buffer *buf)
	Get the start address of the buffer. More...
__api void *	iio_buffer_first (const struct iio_buffer *buf, const struct iio_channel *chn)
	Find the first sample of a channel in a buffer. More...
__api ptrdiff_t	iio_buffer_step (const struct iio_buffer *buf)
	Get the step size between two samples of one channel. More...
__api void *	iio_buffer_end (const struct iio_buffer *buf)
	Get the address that follows the last sample in a buffer. More...
__api ssize_t	iio_buffer_foreach_sample (struct iio_buffer *buf, ssize_t(*callback)(const struct iio_channel *chn, void *src, size_t bytes, void *d), void *data)
	Call the supplied callback for each sample found in a buffer. More...
__api void	iio_buffer_set_data (struct iio_buffer *buf, void *data)
	Associate a pointer to an iio_buffer structure. More...
__api void *	iio_buffer_get_data (const struct iio_buffer *buf)
	Retrieve a previously associated pointer of an iio_buffer structure. More...

Detailed Description

Function Documentation

iio_buffer_destroy()

__api void iio_buffer_destroy

(

struct iio_buffer *

buf

)

Destroy the given buffer.

Parameters

buf	A pointer to an iio_buffer structure

NOTE: After that function, the iio_buffer pointer shall be invalid.

iio_buffer_end()

__api void* iio_buffer_end

(

const struct iio_buffer *

buf

)

Get the address that follows the last sample in a buffer.

Parameters

buf	A pointer to an iio_buffer structure

Returns

A pointer corresponding to the address that follows the last sample present in the buffer

iio_buffer_first()

__api void* iio_buffer_first	(	const struct iio_buffer *	buf,
		const struct iio_channel *	chn
	)

Find the first sample of a channel in a buffer.

Parameters

buf	A pointer to an iio_buffer structure
chn	A pointer to an iio_channel structure

Returns

A pointer to the first sample found, or to the end of the buffer if no sample for the given channel is present in the buffer

NOTE: This fonction, coupled with iio_buffer_step and iio_buffer_end, can be used to iterate on all the samples of a given channel present in the buffer, doing the following:

for (void *ptr = iio_buffer_first(buffer, chn); ptr < iio_buffer_end(buffer); ptr += iio_buffer_step(buffer)) {
   ....
}

iio_buffer_foreach_sample()

__api ssize_t iio_buffer_foreach_sample	(	struct iio_buffer *	buf,
		ssize_t(*)(const struct iio_channel *chn, void *src, size_t bytes, void *d)	callback,
		void *	data
	)

Call the supplied callback for each sample found in a buffer.

Parameters

buf	A pointer to an iio_buffer structure
callback	A pointer to a function to call for each sample found
data	A user-specified pointer that will be passed to the callback

NOTE: The callback receives four arguments:

• A pointer to the iio_channel structure corresponding to the sample,
• A pointer to the sample itself,
• The length of the sample in bytes,
• The user-specified pointer passed to iio_buffer_foreach_sample.

iio_buffer_get_data()

__api void* iio_buffer_get_data

(

const struct iio_buffer *

buf

)

Retrieve a previously associated pointer of an iio_buffer structure.

Parameters

buf	A pointer to an iio_buffer structure

Returns

The pointer previously associated if present, or NULL

iio_buffer_push()

__api ssize_t iio_buffer_push

(

struct iio_buffer *

buf

)

Send the samples to the hardware.

Parameters

buf	A pointer to an iio_buffer structure

Returns

On success, the number of bytes written is returned

On error, a negative errno code is returned

NOTE: Only valid for output buffers

iio_buffer_refill()

__api ssize_t iio_buffer_refill

(

struct iio_buffer *

buf

)

Fetch more samples from the hardware.

Parameters

buf	A pointer to an iio_buffer structure

Returns

On success, the number of bytes read is returned

On error, a negative errno code is returned

NOTE: Only valid for input buffers

iio_buffer_set_data()

__api void iio_buffer_set_data	(	struct iio_buffer *	buf,
		void *	data
	)

Associate a pointer to an iio_buffer structure.

Parameters

buf	A pointer to an iio_buffer structure
data	The pointer to be associated

iio_buffer_start()

__api void* iio_buffer_start

(

const struct iio_buffer *

buf

)

Get the start address of the buffer.

Parameters

buf	A pointer to an iio_buffer structure

Returns

A pointer corresponding to the start address of the buffer

iio_buffer_step()

__api ptrdiff_t iio_buffer_step

(

const struct iio_buffer *

buf

)

Get the step size between two samples of one channel.

Parameters

buf	A pointer to an iio_buffer structure

Returns

the difference between the addresses of two consecutive samples of one same channel

iio_device_create_buffer()

__api struct iio_buffer* iio_device_create_buffer	(	const struct iio_device *	dev,
		size_t	samples_count,
		bool	cyclic
	)

Create an input or output buffer associated to the given device.

Parameters

dev	A pointer to an iio_device structure
samples_count	The number of samples that the buffer should contain
cyclic	If True, enable cyclic mode

Returns

On success, a pointer to an iio_buffer structure

On error, NULL is returned, and errno is set to the error code

NOTE: Channels that have to be written to / read from must be enabled before creating the buffer.