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38 * \brief Declares constants and helper functions used when handling
39 * bounding boxes for clusters of particles.
41 * \author Berk Hess <hess@kth.se>
42 * \ingroup module_nbnxm
45 #ifndef GMX_NBNXM_BOUNDINGBOXES_H
46 #define GMX_NBNXM_BOUNDINGBOXES_H
48 #include "gromacs/simd/simd.h"
53 /*! \brief The number of bounds along one dimension of a bounding box */
54 static constexpr int c_numBoundingBoxBounds1D = 2;
60 /* Bounding box calculations are (currently) always in single precision, so
61 * we only need to check for single precision support here.
62 * This uses less (cache-)memory and SIMD is faster, at least on x86.
64 #if GMX_SIMD4_HAVE_FLOAT
65 # define NBNXN_SEARCH_BB_SIMD4 1
67 # define NBNXN_SEARCH_BB_SIMD4 0
71 #if NBNXN_SEARCH_BB_SIMD4
72 /* Always use 4-wide SIMD for bounding box calculations */
75 /* Single precision BBs + coordinates, we can also load coordinates with SIMD */
76 # define NBNXN_SEARCH_SIMD4_FLOAT_X_BB 1
78 # define NBNXN_SEARCH_SIMD4_FLOAT_X_BB 0
81 /* Store bounding boxes corners as quadruplets: xxxxyyyyzzzz
83 * The packed bounding box coordinate stride is always set to 4.
84 * With AVX we could use 8, but that turns out not to be faster.
86 # define NBNXN_BBXXXX 1
88 //! The number of bounding boxes in a pack, also the size of a pack along one dimension
89 static constexpr int c_packedBoundingBoxesDimSize = GMX_SIMD4_WIDTH;
91 //! Total number of corners (floats) in a pack of bounding boxes
92 static constexpr int c_packedBoundingBoxesSize =
93 c_packedBoundingBoxesDimSize*DIM*Nbnxm::c_numBoundingBoxBounds1D;
95 //! Returns the starting index of the bounding box pack that contains the given cluster
96 static constexpr inline int packedBoundingBoxesIndex(int clusterIndex)
98 return (clusterIndex/c_packedBoundingBoxesDimSize)*c_packedBoundingBoxesSize;
101 #else /* NBNXN_SEARCH_BB_SIMD4 */
103 # define NBNXN_SEARCH_SIMD4_FLOAT_X_BB 0
104 # define NBNXN_BBXXXX 0
106 #endif /* NBNXN_SEARCH_BB_SIMD4 */