src/gromacs/nbnxm/nbnxm_geometry.h

   1 /*
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  36 /*! \internal \file
  37  *
  38  * \brief
  39  * Declares the geometry-related functionality
  40  *
  41  * \author Berk Hess <hess@kth.se>
  42  * \ingroup module_nbnxm
  43  */
  44 #ifndef GMX_NBNXM_NBNXM_GEOMETRY_H
  45 #define GMX_NBNXM_NBNXM_GEOMETRY_H
  46
  47 #include "gromacs/math/vectypes.h"
  48 #include "gromacs/nbnxm/nbnxm.h"
  49 #include "gromacs/simd/simd.h"
  50 #include "gromacs/utility/fatalerror.h"
  51
  52 #include "pairlist.h"
  53
  54
  55 /*! \brief Returns the base-2 log of n.
  56  * *
  57  * Generates a fatal error when n is not an integer power of 2.
  58  */
  59 static inline int get_2log(int n)
  60 {
  61     int log2;
  62
  63     log2 = 0;
  64     while ((1 << log2) < n)
  65     {
  66         log2++;
  67     }
  68     if ((1 << log2) != n)
  69     {
  70         gmx_fatal(FARGS, "nbnxn na_c (%d) is not a power of 2", n);
  71     }
  72
  73     return log2;
  74 }
  75
  76 namespace Nbnxm
  77 {
  78
  79 /*! \brief The nbnxn i-cluster size in atoms for each nbnxn kernel type */
  80 static constexpr gmx::EnumerationArray<KernelType, int> IClusterSizePerKernelType = {
  81     { 0, c_nbnxnCpuIClusterSize, c_nbnxnCpuIClusterSize, c_nbnxnCpuIClusterSize,
  82       c_nbnxnGpuClusterSize, c_nbnxnGpuClusterSize }
  83 };
  84
  85 /*! \brief The nbnxn j-cluster size in atoms for each nbnxn kernel type */
  86 static constexpr gmx::EnumerationArray<KernelType, int> JClusterSizePerKernelType = {
  87     { 0, c_nbnxnCpuIClusterSize,
  88 #if GMX_SIMD
  89       GMX_SIMD_REAL_WIDTH, GMX_SIMD_REAL_WIDTH / 2,
  90 #else
  91       0, 0,
  92 #endif
  93       c_nbnxnGpuClusterSize, c_nbnxnGpuClusterSize / 2 }
  94 };
  95
  96 /*! \brief Returns whether the pair-list corresponding to nb_kernel_type is simple */
  97 static inline bool kernelTypeUsesSimplePairlist(const KernelType kernelType)
  98 {
  99     return (kernelType == KernelType::Cpu4x4_PlainC || kernelType == KernelType::Cpu4xN_Simd_4xN
 100             || kernelType == KernelType::Cpu4xN_Simd_2xNN);
 101 }
 102
 103 //! Returns whether a SIMD kernel is in use
 104 static inline bool kernelTypeIsSimd(const KernelType kernelType)
 105 {
 106     return (kernelType == KernelType::Cpu4xN_Simd_4xN || kernelType == KernelType::Cpu4xN_Simd_2xNN);
 107 }
 108
 109 } // namespace Nbnxm
 110
 111 /*! \brief Returns the effective list radius of the pair-list
 112  *
 113  * Due to the cluster size the effective pair-list is longer than
 114  * that of a simple atom pair-list. This function gives the extra distance.
 115  *
 116  * NOTE: If the i- and j-cluster sizes are identical and you know
 117  *       the physical dimensions of the clusters, use the next function
 118  *       for more accurate results
 119  */
 120 real nbnxn_get_rlist_effective_inc(int jClusterSize, real atomDensity);
 121
 122 /*! \brief Returns the effective list radius of the pair-list
 123  *
 124  * Due to the cluster size the effective pair-list is longer than
 125  * that of a simple atom pair-list. This function gives the extra distance.
 126  */
 127 real nbnxn_get_rlist_effective_inc(int clusterSize, const gmx::RVec& averageClusterBoundingBox);
 128
 129 #endif