amgcl_csr_conversion_utilities.h

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//    |  /           |
//    ' /   __| _` | __|  _ \   __|
//    . \  |   (   | |   (   |\__ \.
//   _|\_\_|  \__,_|\__|\___/ ____/
//                   Multi-Physics
//
//  License:         BSD License
//                   Kratos default license: kratos/license.txt
//
//  Main authors:    Denis Demidov
//                   Riccardo Rossi
//
//
 
#if !defined(KRATOS_CSR_CONVERSION_UTILITIES_H_INCLUDED)
#define  KRATOS_CSR_CONVERSION_UTILITIES_H_INCLUDED
 
// System includes
 
// External includes
#include <amgcl/backend/builtin.hpp>
#include <amgcl/adapter/zero_copy.hpp>
#include <span/span.hpp>
 
// Project includes
#include "containers/csr_matrix.h"
 
namespace Kratos
{
 
class AmgclCSRConversionUtilities
{
 
public:
 
    template< class TDataType, class TIndexType >
    static Kratos::shared_ptr<typename amgcl::backend::builtin<TDataType>::matrix > ConvertToAmgcl(
        const CsrMatrix<TDataType, TIndexType>& rA)
    {
        Kratos::shared_ptr<typename amgcl::backend::builtin<TDataType>::matrix > pAmgcl = amgcl::adapter::zero_copy(
                    rA.size1(),
                    rA.index1_data().begin(),
                    rA.index2_data().begin(),
                    rA.value_data().begin()
                );
        pAmgcl->ncols = rA.size2();
        pAmgcl->own_data = false;
 
        return pAmgcl;
    }
 
 
    //Note that we deliberately return a unique_ptr as it can be moved to a shared_ptr as needed
    template< class TDataType, class TIndexType >
    static typename CsrMatrix<TDataType, TIndexType>::UniquePointer ConvertToCsrMatrix(
        typename amgcl::backend::builtin<TDataType>::matrix& rA
    )
    {
        auto pAconverted = Kratos::make_unique<CsrMatrix<TDataType, TIndexType>>();
 
        if(rA.own_data == false){  //if rA is not the owner, Aconverted cannot be
            pAconverted->SetIsOwnerOfData(false);
        }
        else{  //if rA is the owner, transfer ownership to the csr_matrix
            rA.own_data = false;
            pAconverted->SetIsOwnerOfData(true);
        }
 
        pAconverted->SetRowSize(rA.nrows);
        pAconverted->SetColSize(rA.ncols);
        pAconverted->AssignIndex1Data((TIndexType*)(rA.ptr), rA.nrows+1);
        pAconverted->AssignIndex2Data((TIndexType*)(rA.col), rA.nnz);
        pAconverted->AssignValueData((TDataType*)(rA.val), rA.nnz);
        return pAconverted;
    }
 
    //Note that we deliberately return a unique_ptr as it can be moved to a shared_ptr as needed
    template< class TDataType, class TIndexType >
    static typename CsrMatrix<TDataType, TIndexType>::Pointer Transpose(
        CsrMatrix<TDataType, TIndexType>& rA
    )
    {
        const auto pAamgcl = ConvertToAmgcl<TDataType,TIndexType>(rA);
 
        const auto pAamgcl_transpose = amgcl::backend::transpose(*pAamgcl);
 
        return ConvertToCsrMatrix<TDataType,TIndexType>(*pAamgcl_transpose);
    }
 
};
 
}
 
#endif // KRATOS_CSR_CONVERSION_UTILITIES_H_INCLUDED