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35 /*! \libinternal \file
37 * \brief Basic routines to handle periodic boundary conditions with CUDA.
39 * This file contains GPU implementation of the PBC-aware vector evaluation.
41 * \todo CPU, GPU and SIMD routines essentially do the same operations on
42 * different data-types. Currently this leads to code duplication,
43 * which has to be resolved. For details, see Issue #2863
44 * https://gitlab.com/gromacs/gromacs/-/issues/2863
46 * \author Mark Abraham <mark.j.abraham@gmail.com>
47 * \author Berk Hess <hess@kth.se>
48 * \author Artem Zhmurov <zhmurov@gmail.com>
51 * \ingroup module_pbcutil
53 #ifndef GMX_PBCUTIL_PBC_AIUC_CUDA_CUH
54 #define GMX_PBCUTIL_PBC_AIUC_CUDA_CUH
56 #include "gromacs/gpu_utils/vectype_ops.cuh"
57 #include "gromacs/pbcutil/pbc_aiuc.h"
59 /*! \brief Computes the vector between two points taking PBC into account.
61 * Computes the vector dr between points r2 and r1, taking into account the
62 * periodic boundary conditions, described in pbcAiuc object. Note that this
63 * routine always does the PBC arithmetic for all directions, multiplying the
64 * displacements by zeroes if the corresponding direction is not periodic.
65 * For triclinic boxes only distances up to half the smallest box diagonal
66 * element are guaranteed to be the shortest. This means that distances from
67 * 0.5/sqrt(2) times a box vector length (e.g. for a rhombic dodecahedron)
68 * can use a more distant periodic image.
70 * \todo This routine uses CUDA float4 types for input coordinates and
71 * returns in rvec data-type. Other than that, it does essentially
72 * the same thing as the version below, as well as SIMD and CPU
73 * versions. This routine is used in gpubonded module.
74 * To avoid code duplication, these implementations should be
75 * unified. See Issue #2863:
76 * https://gitlab.com/gromacs/gromacs/-/issues/2863
78 * \param[in] pbcAiuc PBC object.
79 * \param[in] r1 Coordinates of the first point.
80 * \param[in] r2 Coordinates of the second point.
81 * \param[out] dr Resulting distance.
83 template<bool returnShift>
84 static __forceinline__ __device__ int
85 pbcDxAiuc(const PbcAiuc& pbcAiuc, const float4 r1, const float4 r2, float3& dr)
91 float shz = rintf(dr.z * pbcAiuc.invBoxDiagZ);
92 dr.x -= shz * pbcAiuc.boxZX;
93 dr.y -= shz * pbcAiuc.boxZY;
94 dr.z -= shz * pbcAiuc.boxZZ;
96 float shy = rintf(dr.y * pbcAiuc.invBoxDiagY);
97 dr.x -= shy * pbcAiuc.boxYX;
98 dr.y -= shy * pbcAiuc.boxYY;
100 float shx = rintf(dr.x * pbcAiuc.invBoxDiagX);
101 dr.x -= shx * pbcAiuc.boxXX;
107 ishift[XX] = -__float2int_rn(shx);
108 ishift[YY] = -__float2int_rn(shy);
109 ishift[ZZ] = -__float2int_rn(shz);
111 return IVEC2IS(ishift);
119 /*! \brief Computes the vector between two points taking PBC into account.
121 * Computes the vector dr between points r2 and r1, taking into account the
122 * periodic boundary conditions, described in pbcAiuc object. Same as above,
123 * only takes and returns data in float3 format. Does not return shifts.
125 * \todo This routine uses CUDA float3 types for both input and returns
126 * values. Other than that, it does essentially the same thing as the
127 * version above, as well as SIMD and CPU versions. This routine is
128 * used in GPU-based constraints.
129 * To avoid code duplication, these implementations should be
130 * unified. See Issue #2863:
131 * https://gitlab.com/gromacs/gromacs/-/issues/2863
133 * \param[in] pbcAiuc PBC object.
134 * \param[in] r1 Coordinates of the first point.
135 * \param[in] r2 Coordinates of the second point.
136 * \returns dr Resulting distance.
138 static __forceinline__ __host__ __device__ float3 pbcDxAiuc(const PbcAiuc& pbcAiuc,
144 float shz = rintf(dr.z * pbcAiuc.invBoxDiagZ);
145 dr.x -= shz * pbcAiuc.boxZX;
146 dr.y -= shz * pbcAiuc.boxZY;
147 dr.z -= shz * pbcAiuc.boxZZ;
149 float shy = rintf(dr.y * pbcAiuc.invBoxDiagY);
150 dr.x -= shy * pbcAiuc.boxYX;
151 dr.y -= shy * pbcAiuc.boxYY;
153 float shx = rintf(dr.x * pbcAiuc.invBoxDiagX);
154 dr.x -= shx * pbcAiuc.boxXX;
159 #endif // GMX_PBCUTIL_PBC_AIUC_CUDA_CUH