buffer.c

// SPDX-License-Identifier: LGPL-2.1-or-later
/*
 * libiio - Library for interfacing industrial I/O (IIO) devices
 *
 * Copyright (C) 2014-2015 Analog Devices, Inc.
 * Author: Paul Cercueil <paul.cercueil@analog.com>
 */

#include "iio-config.h"
#include "iio-private.h"

#include <errno.h>
#include <string.h>

static bool device_is_high_speed(const struct iio_device *dev)
{
	/* Little trick: We call the backend's get_buffer() function, which is
	 * for now only implemented in the Local backend, with a NULL pointer.
	 * It will return -ENOSYS if the device is not high speed, and either
	 * -EBADF or -EINVAL otherwise. */
	const struct iio_backend_ops *ops = dev->ctx->ops;
	return !!ops->get_buffer &&
		(ops->get_buffer(dev, NULL, 0, NULL, 0) != -ENOSYS);
}

struct iio_buffer * iio_device_create_buffer(const struct iio_device *dev,
		size_t samples_count, bool cyclic)
{
	ssize_t ret = -EINVAL;
	struct iio_buffer *buf;
	ssize_t sample_size = iio_device_get_sample_size(dev);

	if (!sample_size || !samples_count)
		goto err_set_errno;

	if (sample_size < 0) {
		ret = sample_size;
		goto err_set_errno;
	}

	buf = malloc(sizeof(*buf));
	if (!buf) {
		ret = -ENOMEM;
		goto err_set_errno;
	}

	buf->dev_sample_size = (unsigned int) sample_size;
	buf->length = sample_size * samples_count;
	buf->dev = dev;
	buf->mask = calloc(dev->words, sizeof(*buf->mask));
	if (!buf->mask) {
		ret = -ENOMEM;
		goto err_free_buf;
	}

	/* Set the default channel mask to the one used by the device.
	 * While input buffers will erase this as soon as the refill function
	 * is used, it is useful for output buffers, as it permits
	 * iio_buffer_foreach_sample to be used. */
	memcpy(buf->mask, dev->mask, dev->words * sizeof(*buf->mask));

	ret = iio_device_open(dev, samples_count, cyclic);
	if (ret < 0)
		goto err_free_mask;

	buf->dev_is_high_speed = device_is_high_speed(dev);
	if (buf->dev_is_high_speed) {
		/* Dequeue the first buffer, so that buf->buffer is correctly
		 * initialized */
		buf->buffer = NULL;
		if (iio_device_is_tx(dev)) {
			ret = dev->ctx->ops->get_buffer(dev, &buf->buffer,
					buf->length, buf->mask, dev->words);
			if (ret < 0)
				goto err_close_device;
		}
	} else {
		buf->buffer = malloc(buf->length);
		if (!buf->buffer) {
			ret = -ENOMEM;
			goto err_close_device;
		}
	}

	ret = iio_device_get_sample_size_mask(dev, buf->mask, dev->words);
	if (ret < 0)
		goto err_close_device;

	buf->sample_size = (unsigned int) ret;
	buf->data_length = buf->length;
	return buf;

err_close_device:
	iio_device_close(dev);
err_free_mask:
	free(buf->mask);
err_free_buf:
	free(buf);
err_set_errno:
	errno = -(int)ret;
	return NULL;
}

void iio_buffer_destroy(struct iio_buffer *buffer)
{
	iio_device_close(buffer->dev);
	if (!buffer->dev_is_high_speed)
		free(buffer->buffer);
	free(buffer->mask);
	free(buffer);
}

int iio_buffer_get_poll_fd(struct iio_buffer *buffer)
{
	return iio_device_get_poll_fd(buffer->dev);
}

int iio_buffer_set_blocking_mode(struct iio_buffer *buffer, bool blocking)
{
	return iio_device_set_blocking_mode(buffer->dev, blocking);
}

ssize_t iio_buffer_refill(struct iio_buffer *buffer)
{
	ssize_t read;
	const struct iio_device *dev = buffer->dev;
	ssize_t ret;

	if (buffer->dev_is_high_speed) {
		read = dev->ctx->ops->get_buffer(dev, &buffer->buffer,
				buffer->length, buffer->mask, dev->words);
	} else {
		read = iio_device_read_raw(dev, buffer->buffer, buffer->length,
				buffer->mask, dev->words);
	}

	if (read >= 0) {
		buffer->data_length = read;
		ret = iio_device_get_sample_size_mask(dev, buffer->mask, dev->words);
		if (ret < 0)
			return ret;
		buffer->sample_size = (unsigned int)ret;
	}
	return read;
}

ssize_t iio_buffer_push(struct iio_buffer *buffer)
{
	const struct iio_device *dev = buffer->dev;
	ssize_t ret;

	if (buffer->dev_is_high_speed) {
		void *buf;
		ret = dev->ctx->ops->get_buffer(dev, &buf,
				buffer->data_length, buffer->mask, dev->words);
		if (ret >= 0) {
			buffer->buffer = buf;
			ret = (ssize_t) buffer->data_length;
		}
	} else {
		void *ptr = buffer->buffer;
		size_t tmp_len;

		/* iio_device_write_raw doesn't guarantee that all bytes are
		 * written */
		for (tmp_len = buffer->data_length; tmp_len; ) {
			ret = iio_device_write_raw(dev, ptr, tmp_len);
			if (ret < 0)
				goto out_reset_data_length;

			tmp_len -= ret;
			ptr = (void *) ((uintptr_t) ptr + ret);
		}

		ret = (ssize_t) buffer->data_length;
	}

out_reset_data_length:
	buffer->data_length = buffer->length;
	return ret;
}

ssize_t iio_buffer_push_partial(struct iio_buffer *buffer, size_t samples_count)
{
	size_t new_len = samples_count * buffer->dev_sample_size;

	if (new_len == 0 || new_len > buffer->length)
		return -EINVAL;

	buffer->data_length = new_len;
	return iio_buffer_push(buffer);
}

ssize_t iio_buffer_foreach_sample(struct iio_buffer *buffer,
		ssize_t (*callback)(const struct iio_channel *,
			void *, size_t, void *), void *d)
{
	uintptr_t ptr = (uintptr_t) buffer->buffer,
		  start = ptr,
		  end = ptr + buffer->data_length;
	const struct iio_device *dev = buffer->dev;
	ssize_t processed = 0;

	if (buffer->sample_size == 0)
		return -EINVAL;

	if (buffer->data_length < buffer->dev_sample_size)
		return 0;

	while (end - ptr >= (size_t) buffer->sample_size) {
		unsigned int i;

		for (i = 0; i < dev->nb_channels; i++) {
			const struct iio_channel *chn = dev->channels[i];
			unsigned int length = chn->format.length / 8;

			if (chn->index < 0)
				break;

			/* Test if the buffer has samples for this channel */
			if (!TEST_BIT(buffer->mask, chn->number))
				continue;

			if ((ptr - start) % length)
				ptr += length - ((ptr - start) % length);

			/* Test if the client wants samples from this channel */
			if (TEST_BIT(dev->mask, chn->number)) {
				ssize_t ret = callback(chn,
						(void *) ptr, length, d);
				if (ret < 0)
					return ret;
				else
					processed += ret;
			}

			if (i == dev->nb_channels - 1 || dev->channels[
					i + 1]->index != chn->index)
				ptr += length * chn->format.repeat;
		}
	}
	return processed;
}

void * iio_buffer_start(const struct iio_buffer *buffer)
{
	return buffer->buffer;
}

void * iio_buffer_first(const struct iio_buffer *buffer,
		const struct iio_channel *chn)
{
	size_t len;
	unsigned int i;
	uintptr_t ptr = (uintptr_t) buffer->buffer,
		  start = ptr;

	if (!iio_channel_is_enabled(chn))
		return iio_buffer_end(buffer);

	for (i = 0; i < buffer->dev->nb_channels; i++) {
		struct iio_channel *cur = buffer->dev->channels[i];
		len = cur->format.length / 8 * cur->format.repeat;

		/* NOTE: dev->channels are ordered by index */
		if (cur->index < 0 || cur->index == chn->index)
			break;

		/* Test if the buffer has samples for this channel */
		if (!TEST_BIT(buffer->mask, cur->number))
			continue;

		/* Two channels with the same index use the same samples */
		if (i > 0 && cur->index == buffer->dev->channels[i - 1]->index)
			continue;

		if ((ptr - start) % len)
			ptr += len - ((ptr - start) % len);
		ptr += len;
	}

	len = chn->format.length / 8;
	if ((ptr - start) % len)
		ptr += len - ((ptr - start) % len);
	return (void *) ptr;
}

ptrdiff_t iio_buffer_step(const struct iio_buffer *buffer)
{
	return (ptrdiff_t) buffer->sample_size;
}

void * iio_buffer_end(const struct iio_buffer *buffer)
{
	return (void *) ((uintptr_t) buffer->buffer + buffer->data_length);
}

void iio_buffer_set_data(struct iio_buffer *buf, void *data)
{
	buf->userdata = data;
}

void * iio_buffer_get_data(const struct iio_buffer *buf)
{
	return buf->userdata;
}

const struct iio_device * iio_buffer_get_device(const struct iio_buffer *buf)
{
	return buf->dev;
}

void iio_buffer_cancel(struct iio_buffer *buf)
{
	const struct iio_backend_ops *ops = buf->dev->ctx->ops;

	if (ops->cancel)
		ops->cancel(buf->dev);
}