#ifndef VIENNACL_LINALG_HOST_BASED_MISC_OPERATIONS_HPP_
#define VIENNACL_LINALG_HOST_BASED_MISC_OPERATIONS_HPP_

/* =========================================================================
   Copyright (c) 2010-2012, Institute for Microelectronics,
                            Institute for Analysis and Scientific Computing,
                            TU Wien.
   Portions of this software are copyright by UChicago Argonne, LLC.

                            -----------------
                  ViennaCL - The Vienna Computing Library
                            -----------------

   Project Head:    Karl Rupp                   rupp@iue.tuwien.ac.at
               
   (A list of authors and contributors can be found in the PDF manual)

   License:         MIT (X11), see file LICENSE in the base directory
============================================================================= */

/** @file viennacl/linalg/host_based/misc_operations.hpp
    @brief Implementations of miscellaneous operations on the CPU using a single thread or OpenMP.
*/

#include <list>

#include "viennacl/forwards.h"
#include "viennacl/scalar.hpp"
#include "viennacl/vector.hpp"
#include "viennacl/tools/tools.hpp"
#include "viennacl/linalg/host_based/common.hpp"

namespace viennacl
{
  namespace linalg
  {
    namespace host_based
    {
      namespace detail
      {
        template <typename ScalarType>
        void level_scheduling_substitute(vector<ScalarType> & vec,
                                     viennacl::backend::mem_handle const & row_index_array,
                                     viennacl::backend::mem_handle const & row_buffer,
                                     viennacl::backend::mem_handle const & col_buffer,
                                     viennacl::backend::mem_handle const & element_buffer,
                                     std::size_t num_rows
                                    )
        {
          ScalarType * vec_buf = viennacl::linalg::host_based::detail::extract_raw_pointer<ScalarType>(vec.handle());
          
          unsigned int const * elim_row_index  = viennacl::linalg::host_based::detail::extract_raw_pointer<unsigned int>(row_index_array);
          unsigned int const * elim_row_buffer = viennacl::linalg::host_based::detail::extract_raw_pointer<unsigned int>(row_buffer);
          unsigned int const * elim_col_buffer = viennacl::linalg::host_based::detail::extract_raw_pointer<unsigned int>(col_buffer);
          ScalarType   const * elim_elements   = viennacl::linalg::host_based::detail::extract_raw_pointer<ScalarType>(element_buffer);
          
#ifdef VIENNACL_WITH_OPENMP
          #pragma omp parallel for
#endif
          for (std::size_t row=0; row < num_rows; ++row)
          {
            unsigned int eq_row = elim_row_index[row];
            ScalarType vec_entry = vec_buf[eq_row];
            unsigned int row_end = elim_row_buffer[row+1];
            
            for (std::size_t j = elim_row_buffer[row]; j < row_end; ++j)
              vec_entry -= vec_buf[elim_col_buffer[j]] * elim_elements[j];
            
            vec_buf[eq_row] = vec_entry;
          }
            
        }
      }
      
    } // namespace host_based
  } //namespace linalg
} //namespace viennacl


#endif
