Thank you, Karl!
Aha, so the fast_copy looks like something I need.
One question: you mentioned padding for the `matrix` type. When i
initialize the `matrix` instance, i only specify dimensions. how do I know
padding values?
On Tue, Jul 12, 2016 at 5:53 AM, Karl Rupp <r...@iue.tuwien.ac.at> wrote:
> Hi Dmitriy,
>
> On 07/12/2016 07:17 AM, Dmitriy Lyubimov wrote:
>
>> Hi,
>>
>> I am trying to create some elementary wrappers for VCL in javacpp.
>>
>> Everything goes fine, except i really would rather not use those "cpu"
>> types (std::map,
>> std::vector) and rather initialize matrices directly by feeding
>> row-major or CCS formats.
>>
>> I see that matrix () constructor accepts this form of initialization;
>> but it really states that
>> it does "wrapping" for the device memory.
>>
>
> Yes, the constructors either create their own memory buffer
> (zero-initialized) or wrap an existing buffer. These are the only
> reasonable options.
>
>
> Now, i can create a host matrix() using host memory and row-major
>> packing. This works ok it seems.
>>
>> However, these are still host instances. Can i copy host instances to
>> instances on opencl context?
>>
>
> Did you look at viennacl::copy() or viennacl::fast_copy()?
>
>
> That might be one way bypassing unnecessary (in my case) complexities of
>> working with std::vector and std::map classes from java side.
>>
>> But it looks like there's no copy() variation that would accept a
>> matrix-on-host and matrix-on-opencl arguments (or rather, it of course
>> declares those to be ambiguous since two methods fit).
>>
>
> If you want to copy your OpenCL data into a viennacl::matrix, you may wrap
> the memory handle (obtained with .elements()) into a vector and copy that.
> If you have plain host data, use viennacl::fast_copy() and mind the data
> layout (padding of rows/columns!)
>
>
> For compressed_matrix, there seems to be a set() method, but i guess
>> this also requires CCS arrays in the device memory if I use it. Same
>> question, is there a way to send-and-wrap CCS arrays to an opencl device
>> instance of compressed matrix without using std::map?
>>
>
> Currently you have to use .set() if you want to bypass viennacl::copy()
> and std::map.
>
> I acknowledge that the C++ type system is a pain when interfacing from
> other languages. We will make this much more convenient in ViennaCL 2.0.
> The existing interface in ViennaCL 1.x is too hard to fix without breaking
> lots of user code, so we won't invest time in that (contributions welcome,
> though :-) )
>
> Best regards,
> Karli
>
>
>
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