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/*! \internal \file
 * \brief This file defines the PME CUDA-specific data structure,
 * various compile-time constants shared among the PME CUDA kernels,
 * and also names some PME CUDA memory management routines.
 * TODO: consider changing defines into variables where possible; have inline getters.
 *
 * \author Aleksei Iupinov <a.yupinov@gmail.com>
 */

#ifndef GMX_EWALD_PME_CUH
#define GMX_EWALD_PME_CUH

#include <cassert>

#include "pme-gpu-constants.h"
#include "pme-gpu-internal.h"
#include "pme-gpu-types.h"
#include "pme-gpu-types-host.h"
#include "pme-gpu-types-host-impl.h"

/*! \brief \internal
 * An inline CUDA function for checking the global atom data indices against the atom data array sizes.
 *
 * \param[in] atomDataIndexGlobal  The atom data index.
 * \param[in] nAtomData            The atom data array element count.
 * \returns                        Non-0 if index is within bounds (or PME data padding is enabled), 0 otherwise.
 *
 * This is called from the spline_and_spread and gather PME kernels.
 * The goal is to isolate the global range checks, and allow avoiding them with c_usePadding enabled.
 */
int __device__ __forceinline__ pme_gpu_check_atom_data_index(const int atomDataIndex, const int nAtomData)
{
    return c_usePadding ? 1 : (atomDataIndex < nAtomData);
}

/*! \brief \internal
 * An inline CUDA function for skipping the zero-charge atoms.
 *
 * \returns                        Non-0 if atom should be processed, 0 otherwise.
 * \param[in] coefficient          The atom charge.
 *
 * This is called from the spline_and_spread and gather PME kernels.
 */
int __device__ __forceinline__ pme_gpu_check_atom_charge(const float coefficient)
{
    assert(isfinite(coefficient));
    return c_skipNeutralAtoms ? (coefficient != 0.0f) : 1;
}

/*! \brief \internal
 * A single structure encompassing all the PME data used in CUDA kernels.
 * This inherits from PmeGpuKernelParamsBase and adds a couple cudaTextureObject_t handles,
 * which we would like to avoid in plain C++.
 */
struct PmeGpuCudaKernelParams : PmeGpuKernelParamsBase
{
    /* These are CUDA texture objects, related to the grid size. */
    /*! \brief CUDA texture object for accessing grid.d_fractShiftsTable */
    cudaTextureObject_t fractShiftsTableTexture;
    /*! \brief CUDA texture object for accessing grid.d_gridlineIndicesTable */
    cudaTextureObject_t gridlineIndicesTableTexture;
};

#endif