entry_proxy.hpp

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#ifndef VIENNACL_TOOLS_ENTRY_PROXY_HPP_
#define VIENNACL_TOOLS_ENTRY_PROXY_HPP_

/* =========================================================================
   Copyright (c) 2010-2015, 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 manual)

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

#include "viennacl/forwards.h"
#include "viennacl/scalar.hpp"

namespace viennacl
{

//proxy class for single vector entries (this is a slow operation!!)
template<typename NumericT>
class entry_proxy
{
public:
  typedef viennacl::backend::mem_handle      handle_type;

  explicit entry_proxy(vcl_size_t mem_offset,
                       handle_type & mem_handle)
    : index_(mem_offset), mem_handle_(mem_handle) {}


  //operators:
  entry_proxy & operator+=(NumericT value)
  {
    NumericT temp = read();
    temp += value;
    write(temp);
    return *this;
  }

  entry_proxy &  operator-=(NumericT value)
  {
    NumericT temp = read();
    temp -= value;
    write(temp);
    return *this;
  }

  entry_proxy &  operator*=(NumericT value)
  {
    NumericT temp = read();
    temp *= value;
    write(temp);
    return *this;
  }

  entry_proxy &  operator/=(NumericT value)
  {
    NumericT temp = read();
    temp /= value;
    write(temp);
    return *this;
  }

  entry_proxy &  operator=(NumericT value)
  {
    write(value);
    return *this;
  }

  entry_proxy & operator=(scalar<NumericT> const & value)
  {
    viennacl::backend::memory_copy(value.handle(), mem_handle_, 0, sizeof(NumericT)*index_, sizeof(NumericT));
    return *this;
  }

  entry_proxy &  operator=(entry_proxy const & other)
  {
    viennacl::backend::memory_copy(other.handle(), mem_handle_, sizeof(NumericT) * other.index_, sizeof(NumericT)*index_, sizeof(NumericT));
    return *this;
  }

  //type conversion:
  // allows to write something like:
  //  double test = vector(4);
  operator NumericT () const
  {
    NumericT temp = read();
    return temp;
  }

  vcl_size_t index() const { return index_; }

  handle_type const & handle() const { return mem_handle_; }

private:
  NumericT read() const
  {
    NumericT temp;
    viennacl::backend::memory_read(mem_handle_, sizeof(NumericT)*index_, sizeof(NumericT), &temp);
    return temp;
  }

  void write(NumericT value)
  {
    viennacl::backend::memory_write(mem_handle_, sizeof(NumericT)*index_, sizeof(NumericT), &value);
  }

  vcl_size_t index_;
  viennacl::backend::mem_handle & mem_handle_;
}; //entry_proxy







template<typename NumericT>
class const_entry_proxy
{
  typedef const_entry_proxy<NumericT>      self_type;
public:
  typedef viennacl::backend::mem_handle      handle_type;

  explicit const_entry_proxy(vcl_size_t mem_offset,
                             handle_type const & mem_handle)
    : index_(mem_offset), mem_handle_(mem_handle) {}


  //type conversion:
  // allows to write something like:
  //  double test = vector(4);
  operator NumericT () const
  {
    NumericT temp = read();
    return temp;
  }

  unsigned int index() const { return index_; }

  handle_type const & handle() const { return mem_handle_; }

private:
  NumericT read() const
  {
    NumericT temp;
    viennacl::backend::memory_read(mem_handle_, sizeof(NumericT)*index_, sizeof(NumericT), &temp);
    return temp;
  }

  vcl_size_t index_;
  viennacl::backend::mem_handle const & mem_handle_;
}; //entry_proxy

}

#endif