Function iio_device_get_sample_size 

pub unsafe extern "C" fn iio_device_get_sample_size(
    dev: *const iio_device,
) -> isize

@brief Get the current sample size @param dev A pointer to an iio_device structure @return On success, the sample size in bytes @return On error, a negative errno code is returned

NOTE: The sample size is not constant and will change when channels get enabled or disabled.