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/**
 * @file MemBackendCudaImpl.hpp
 *
 * @author Cosmin G. Petra <petra1@llnl.gov>, LLNL
 * 
 */

/**
 * This file contains CUDA implementation of memory backend. Should be generally included 
 * only in CUDA compilation units.
 */

#ifndef HIOP_MEM_BCK_CUDA
#define HIOP_MEM_BCK_CUDA

#include <ExecSpace.hpp>

#include <cuda_runtime.h>
#include <cassert>

namespace hiop
{
//
// Memory management
//
template<typename T, typename I>
struct AllocImpl<MemBackendCuda, T, I>
{
  inline static T* alloc(MemBackendCuda& mb, const I& n)
  {
    T* p;
    auto err = cudaMalloc((void**)&p, n*sizeof(T));
    assert(cudaSuccess==err);
    return p;
  }
};

template<typename T>
struct DeAllocImpl<MemBackendCuda, T>
{
  inline static void dealloc(MemBackendCuda& mb, T* p)
  {
    auto err = cudaFree((void*)p);
    assert(cudaSuccess==err);
  }  
};

//
// Transfers
//
template<class EXECPOLDEST, class EXECPOLSRC, typename T, typename I>
struct TransferImpl<MemBackendCuda, EXECPOLDEST, MemBackendCuda, EXECPOLSRC, T, I>
{
  inline static bool do_it(T* p_dest,
                           ExecSpace<MemBackendCuda, EXECPOLDEST>& hwb_dest,
                           const T* p_src,
                           const ExecSpace<MemBackendCuda, EXECPOLSRC>& hwb_src,
                           const I& n)
  {
    cudaError_t err = cudaMemcpy(p_dest, p_src, n*sizeof(T), cudaMemcpyDeviceToDevice);
    assert(err == cudaSuccess);
    return cudaSuccess == err;
  }
};

template<class EXECPOLDEST, class EXECPOLSRC, typename T, typename I>
struct TransferImpl<MemBackendCuda, EXECPOLDEST, MemBackendCpp, EXECPOLSRC, T, I>
{
  inline static bool do_it(T* p_dest,
                           ExecSpace<MemBackendCuda, EXECPOLDEST>& hwb_dest,
                           const T* p_src,
                           const ExecSpace<MemBackendCpp, EXECPOLSRC>& hwb_src,
                           const I& n)
  {
    auto err = cudaMemcpy(p_dest, p_src, n*sizeof(T), cudaMemcpyHostToDevice);
    assert(cudaSuccess == err);
    return cudaSuccess == err;
  }
};

template<class EXECPOLDEST, class EXECPOLSRC, typename T, typename I>
struct TransferImpl<MemBackendCpp, EXECPOLDEST, MemBackendCuda, EXECPOLSRC, T, I>
{
  inline static bool do_it(T* p_dest,
                           ExecSpace<MemBackendCpp, EXECPOLDEST>& hwb_dest,
                           const T* p_src,
                           const ExecSpace<MemBackendCuda, EXECPOLSRC>& hwb_src,
                           const I& n)
  {
    auto err = cudaMemcpy(p_dest, p_src, n*sizeof(T), cudaMemcpyDeviceToHost);
    assert(cudaSuccess == err);
    return cudaSuccess == err;
  }
};

} // end namespace hiop
#endif //HIOP_MEM_BCK_CUDA


