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35 /*! \libinternal \file
37 * \brief This file contains a definition, declaration and inline function
38 * for SIMD accelerated PBC calculations.
40 * \author Berk Hess <hess@kth.se>
42 * \ingroup module_pbcutil
45 #ifndef GMX_PBCUTIL_PBC_SIMD_H
46 #define GMX_PBCUTIL_PBC_SIMD_H
50 #include "gromacs/pbcutil/pbc.h"
51 #include "gromacs/simd/simd.h"
52 #include "gromacs/utility/fatalerror.h"
60 /*! \brief Structure containing the PBC setup for SIMD PBC calculations.
62 * Without SIMD this is a dummy struct, so it can be declared and passed.
63 * This can avoid some ifdef'ing.
66 #ifdef GMX_SIMD_HAVE_REAL
67 gmx_simd_real_t inv_bzz; /**< 1/box[ZZ][ZZ] */
68 gmx_simd_real_t inv_byy; /**< 1/box[YY][YY] */
69 gmx_simd_real_t inv_bxx; /**< 1/box[XX][XX] */
70 gmx_simd_real_t bzx; /**< box[ZZ][XX] */
71 gmx_simd_real_t bzy; /**< box[ZZ][YY] */
72 gmx_simd_real_t bzz; /**< box[ZZ][ZZ] */
73 gmx_simd_real_t byx; /**< box[YY][XX] */
74 gmx_simd_real_t byy; /**< box[YY][YY] */
75 gmx_simd_real_t bxx; /**< bo[XX][XX] */
77 int dum; /**< Dummy variable to avoid empty struct */
83 /*! \brief Set the SIMD PBC data from a normal t_pbc struct.
85 * NULL can be passed for \p pbc, then no PBC will be used.
87 void set_pbc_simd(const t_pbc *pbc,
88 pbc_simd_t *pbc_simd);
90 #if defined GMX_SIMD_HAVE_REAL
92 /*! \brief Correct SIMD distance vector *dx,*dy,*dz for PBC using SIMD.
94 * For rectangular boxes all returned distance vectors are the shortest.
95 * For triclinic boxes only distances up to half the smallest box diagonal
96 * element are guaranteed to be the shortest. This means that distances from
97 * 0.5/sqrt(2) times a box vector length (e.g. for a rhombic dodecahedron)
98 * can use a more distant periodic image.
99 * Note that this routine always does PBC arithmetic, even for dimensions
100 * without PBC. But on modern processors the overhead of this, often called,
101 * routine should be low. On e.g. Intel Haswell/Broadwell it takes 8 cycles.
103 static gmx_inline void gmx_simdcall
104 pbc_correct_dx_simd(gmx_simd_real_t *dx,
107 const pbc_simd_t *pbc)
109 gmx_simd_real_t shz, shy, shx;
111 #if defined _MSC_VER && _MSC_VER < 1700
112 /* The caller side should make sure we never end up here.
113 * TODO Black-list _MSC_VER < 1700 when it's old enough, so we can rid
114 * of this code complication.
116 gmx_incons("pbc_correct_dx_simd was called for code compiled with MSVC 2010 or older, which produces incorrect code (probably corrupts memory) and therefore this function should not have been called");
119 shz = gmx_simd_round_r(gmx_simd_mul_r(*dz, pbc->inv_bzz));
120 *dx = gmx_simd_fnmadd_r(shz, pbc->bzx, *dx);
121 *dy = gmx_simd_fnmadd_r(shz, pbc->bzy, *dy);
122 *dz = gmx_simd_fnmadd_r(shz, pbc->bzz, *dz);
124 shy = gmx_simd_round_r(gmx_simd_mul_r(*dy, pbc->inv_byy));
125 *dx = gmx_simd_fnmadd_r(shy, pbc->byx, *dx);
126 *dy = gmx_simd_fnmadd_r(shy, pbc->byy, *dy);
128 shx = gmx_simd_round_r(gmx_simd_mul_r(*dx, pbc->inv_bxx));
129 *dx = gmx_simd_fnmadd_r(shx, pbc->bxx, *dx);
132 #endif /* GMX_SIMD_HAVE_REAL */