Is it possible to create an Boost Compute vector and wrap a vexcl vector with Compute vector?

[kafi350]

As given in the documentation we can do it for the vexcl but not for the compute vecotrs.

[ddemidov]

Both boost.compute and vexcl vectors are just wrappers around raw opencl buffers, so the conversion is possible both ways.

[kafi350]

// Wrap boost.compute vectors into vexcl vectors (no data is copied):
compute::vector bcv(n, bcq.get_context());
vex::vector y({bcq}, bcv.get_buffer());
y = x * 2;

this is the way to wrap a compute vector but is it possible to wrap a vex vector?

[ddemidov]

See examples in <vexcl/external/boost_compute.hpp>, which uses Boost.compute algorithms with vexcl vectors:

vexcl/vexcl/external/boost_compute.hpp

Lines 60 to 102 in ec0cc1f

	/// Inclusive scan.
	template <typename T>
	void inclusive_scan(const vex::vector<T> &src, vex::vector<T> &dst) {
	auto queue = src.queue_list();
	// Scan partitions separately.
	for(unsigned d = 0; d < queue.size(); ++d) {
	if (src.part_size(d)) {
	boost::compute::command_queue q( queue[d]() );
	boost::compute::buffer sbuf( src(d).raw() );
	boost::compute::buffer dbuf( dst(d).raw() );
	boost::compute::inclusive_scan(
	boost::compute::make_buffer_iterator<T>(sbuf, 0),
	boost::compute::make_buffer_iterator<T>(sbuf, src.part_size(d)),
	boost::compute::make_buffer_iterator<T>(dbuf, 0),
	q
	);
	}
	}
	// If there are more than one partition,
	// update all of them except for the first.
	if (queue.size() > 1) {
	std::vector<T> tail(queue.size() - 1, T());
	for(unsigned d = 0; d < tail.size(); ++d) {
	if (src.part_size(d))
	tail[d] = dst[src.part_start(d + 1) - 1];
	}
	std::partial_sum(tail.begin(), tail.end(), tail.begin());
	for(unsigned d = 1; d < queue.size(); ++d) {
	if (src.part_size(d)) {
	// Wrap partition into vector for ease of use:
	vex::vector<T> part(queue[d], dst(d));
	part += tail[d - 1];
	}
	}
	}
	}