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/*! \libinternal \file
 *
 * \brief This file contains declarations necessary for low-level
 * functions for computing energies and forces for bonded interactions.
 *
 * \author Mark Abraham <mark.j.abraham@gmail.com>
 * \inlibraryapi
 * \ingroup module_listed_forces
 */

#ifndef GMX_LISTED_FORCES_BONDED_H
#define GMX_LISTED_FORCES_BONDED_H

#include <string>

#include "gromacs/libgromacs_export.h"
#include "gromacs/math/vectypes.h"
#include "gromacs/topology/ifunc.h"
#include "gromacs/utility/basedefinitions.h"

struct gmx_cmap_t;
struct t_fcdata;
struct t_nrnb;
struct t_pbc;
struct t_disresdata;
struct t_oriresdata;

namespace gmx
{
template<typename EnumType, typename DataType, EnumType ArraySize>
struct EnumerationArray;
template<typename>
class ArrayRef;
} // namespace gmx

/*! \brief Calculate bond-angle. No PBC is taken into account (use mol-shift) */
real bond_angle(const rvec          xi,
                const rvec          xj,
                const rvec          xk,
                const struct t_pbc* pbc,
                rvec                r_ij,
                rvec                r_kj,
                real*               costh,
                int*                t1,
                int*                t2); /* out */

/*! \brief Calculate dihedral-angle. No PBC is taken into account (use mol-shift) */
real dih_angle(const rvec          xi,
               const rvec          xj,
               const rvec          xk,
               const rvec          xl,
               const struct t_pbc* pbc,
               rvec                r_ij,
               rvec                r_kj,
               rvec                r_kl,
               rvec                m,
               rvec                n, /* out */
               int*                t1,
               int*                t2,
               int*                t3);

/*! \brief Do an update of the forces for dihedral potentials */
void do_dih_fup(int                 i,
                int                 j,
                int                 k,
                int                 l,
                real                ddphi,
                rvec                r_ij,
                rvec                r_kj,
                rvec                r_kl,
                rvec                m,
                rvec                n,
                rvec4               f[],
                rvec                fshift[],
                const struct t_pbc* pbc,
                const rvec*         x,
                int                 t1,
                int                 t2,
                int                 t3);

/*! \brief Make a dihedral fall in the range (-pi,pi) */
void make_dp_periodic(real* dp);

/*! \brief Compute CMAP dihedral energies and forces */
real cmap_dihs(int                 nbonds,
               const t_iatom       forceatoms[],
               const t_iparams     forceparams[],
               const gmx_cmap_t*   cmap_grid,
               const rvec          x[],
               rvec4               f[],
               rvec                fshift[],
               const struct t_pbc* pbc,
               real gmx_unused     lambda,
               real gmx_unused* dvdlambda,
               gmx::ArrayRef<const real> /*charge*/,
               t_fcdata gmx_unused* fcd,
               t_disresdata gmx_unused* disresdata,
               t_oriresdata gmx_unused* oriresdata,
               int gmx_unused* global_atom_index);

/*! \brief For selecting which flavor of bonded kernel is used for simple bonded types */
enum class BondedKernelFlavor
{
    ForcesSimdWhenAvailable, //!< Compute only forces, use SIMD when available; should not be used with perturbed parameters
    ForcesNoSimd,             //!< Compute only forces, do not use SIMD
    ForcesAndVirialAndEnergy, //!< Compute forces, virial and energy (no SIMD)
    ForcesAndEnergy,          //!< Compute forces and energy (no SIMD)
    Count                     //!< The number of flavors
};

//! Helper strings for human-readable messages
extern LIBGROMACS_EXPORT const gmx::EnumerationArray<BondedKernelFlavor, std::string, BondedKernelFlavor::Count> c_bondedKernelFlavorStrings;

/*! \brief Returns whether the energy should be computed */
static constexpr inline bool computeEnergy(const BondedKernelFlavor flavor)
{
    return (flavor == BondedKernelFlavor::ForcesAndVirialAndEnergy
            || flavor == BondedKernelFlavor::ForcesAndEnergy);
}

/*! \brief Returns whether the virial should be computed */
static constexpr inline bool computeVirial(const BondedKernelFlavor flavor)
{
    return (flavor == BondedKernelFlavor::ForcesAndVirialAndEnergy);
}

/*! \brief Returns whether the energy and/or virial should be computed */
static constexpr inline bool computeEnergyOrVirial(const BondedKernelFlavor flavor)
{
    return (flavor == BondedKernelFlavor::ForcesAndVirialAndEnergy
            || flavor == BondedKernelFlavor::ForcesAndEnergy);
}

/*! \brief Calculates bonded interactions for simple bonded types
 *
 * Exits with an error when the bonded type is not simple
 * All pointers should be non-null, except for pbc and g which can be nullptr.
 * \returns the energy or 0 when \p bondedKernelFlavor did not request the energy.
 */
real calculateSimpleBond(int                       ftype,
                         int                       numForceatoms,
                         const t_iatom             forceatoms[],
                         const t_iparams           forceparams[],
                         const rvec                x[],
                         rvec4                     f[],
                         rvec                      fshift[],
                         const struct t_pbc*       pbc,
                         real                      lambda,
                         real*                     dvdlambda,
                         gmx::ArrayRef<const real> charge,
                         t_fcdata*                 fcd,
                         t_disresdata*             disresdata,
                         t_oriresdata*             oriresdata,
                         int gmx_unused*    global_atom_index,
                         BondedKernelFlavor bondedKernelFlavor);

//! Getter for finding the flop count for an \c ftype interaction.
int nrnbIndex(int ftype);

#endif
