src/gromacs/ewald/pme-gather.cpp

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  37
  38 #include "gmxpre.h"
  39
  40 #include "pme-gather.h"
  41
  42 #include "gromacs/ewald/pme-internal.h"
  43 #include "gromacs/ewald/pme-simd.h"
  44 #include "gromacs/ewald/pme-spline-work.h"
  45 #include "gromacs/math/vec.h"
  46 #include "gromacs/utility/smalloc.h"
  47
  48 #define DO_FSPLINE(order)                      \
  49     for (ithx = 0; (ithx < order); ithx++)              \
  50     {                                              \
  51         index_x = (i0+ithx)*pny*pnz;               \
  52         tx      = thx[ithx];                       \
  53         dx      = dthx[ithx];                      \
  54                                                \
  55         for (ithy = 0; (ithy < order); ithy++)          \
  56         {                                          \
  57             index_xy = index_x+(j0+ithy)*pnz;      \
  58             ty       = thy[ithy];                  \
  59             dy       = dthy[ithy];                 \
  60             fxy1     = fz1 = 0;                    \
  61                                                \
  62             for (ithz = 0; (ithz < order); ithz++)      \
  63             {                                      \
  64                 gval  = grid[index_xy+(k0+ithz)];  \
  65                 fxy1 += thz[ithz]*gval;            \
  66                 fz1  += dthz[ithz]*gval;           \
  67             }                                      \
  68             fx += dx*ty*fxy1;                      \
  69             fy += tx*dy*fxy1;                      \
  70             fz += tx*ty*fz1;                       \
  71         }                                          \
  72     }
  73
  74
  75 void gather_f_bsplines(struct gmx_pme_t *pme, real *grid,
  76                        gmx_bool bClearF, pme_atomcomm_t *atc,
  77                        splinedata_t *spline,
  78                        real scale)
  79 {
  80     /* sum forces for local particles */
  81     int                     nn, n, ithx, ithy, ithz, i0, j0, k0;
  82     int                     index_x, index_xy;
  83     int                     nx, ny, nz, pny, pnz;
  84     int                 *   idxptr;
  85     real                    tx, ty, dx, dy, coefficient;
  86     real                    fx, fy, fz, gval;
  87     real                    fxy1, fz1;
  88     real                   *thx, *thy, *thz, *dthx, *dthy, *dthz;
  89     int                     norder;
  90     real                    rxx, ryx, ryy, rzx, rzy, rzz;
  91     int                     order;
  92
  93 #ifdef PME_SIMD4_SPREAD_GATHER
  94     // cppcheck-suppress unreadVariable cppcheck seems not to analyze code from pme-simd4.h
  95     struct pme_spline_work *work = pme->spline_work;
  96 #ifndef PME_SIMD4_UNALIGNED
  97     real                    thz_buffer[GMX_SIMD4_WIDTH*3],  *thz_aligned;
  98     real                    dthz_buffer[GMX_SIMD4_WIDTH*3], *dthz_aligned;
  99
 100     thz_aligned  = gmx_simd4_align_r(thz_buffer);
 101     dthz_aligned = gmx_simd4_align_r(dthz_buffer);
 102 #endif
 103 #endif
 104
 105     order = pme->pme_order;
 106     nx    = pme->nkx;
 107     ny    = pme->nky;
 108     nz    = pme->nkz;
 109     pny   = pme->pmegrid_ny;
 110     pnz   = pme->pmegrid_nz;
 111
 112     rxx   = pme->recipbox[XX][XX];
 113     ryx   = pme->recipbox[YY][XX];
 114     ryy   = pme->recipbox[YY][YY];
 115     rzx   = pme->recipbox[ZZ][XX];
 116     rzy   = pme->recipbox[ZZ][YY];
 117     rzz   = pme->recipbox[ZZ][ZZ];
 118
 119     for (nn = 0; nn < spline->n; nn++)
 120     {
 121         n           = spline->ind[nn];
 122         coefficient = scale*atc->coefficient[n];
 123
 124         if (bClearF)
 125         {
 126             atc->f[n][XX] = 0;
 127             atc->f[n][YY] = 0;
 128             atc->f[n][ZZ] = 0;
 129         }
 130         if (coefficient != 0)
 131         {
 132             fx     = 0;
 133             fy     = 0;
 134             fz     = 0;
 135             idxptr = atc->idx[n];
 136             norder = nn*order;
 137
 138             i0   = idxptr[XX];
 139             j0   = idxptr[YY];
 140             k0   = idxptr[ZZ];
 141
 142             /* Pointer arithmetic alert, next six statements */
 143             thx  = spline->theta[XX] + norder;
 144             thy  = spline->theta[YY] + norder;
 145             thz  = spline->theta[ZZ] + norder;
 146             dthx = spline->dtheta[XX] + norder;
 147             dthy = spline->dtheta[YY] + norder;
 148             dthz = spline->dtheta[ZZ] + norder;
 149
 150             switch (order)
 151             {
 152                 case 4:
 153 #ifdef PME_SIMD4_SPREAD_GATHER
 154 #ifdef PME_SIMD4_UNALIGNED
 155 #define PME_GATHER_F_SIMD4_ORDER4
 156 #else
 157 #define PME_GATHER_F_SIMD4_ALIGNED
 158 #define PME_ORDER 4
 159 #endif
 160 #include "gromacs/ewald/pme-simd4.h"
 161 #else
 162                     DO_FSPLINE(4);
 163 #endif
 164                     break;
 165                 case 5:
 166 #ifdef PME_SIMD4_SPREAD_GATHER
 167 #define PME_GATHER_F_SIMD4_ALIGNED
 168 #define PME_ORDER 5
 169 #include "gromacs/ewald/pme-simd4.h"
 170 #else
 171                     DO_FSPLINE(5);
 172 #endif
 173                     break;
 174                 default:
 175                     DO_FSPLINE(order);
 176                     break;
 177             }
 178
 179             atc->f[n][XX] += -coefficient*( fx*nx*rxx );
 180             atc->f[n][YY] += -coefficient*( fx*nx*ryx + fy*ny*ryy );
 181             atc->f[n][ZZ] += -coefficient*( fx*nx*rzx + fy*ny*rzy + fz*nz*rzz );
 182         }
 183     }
 184     /* Since the energy and not forces are interpolated
 185      * the net force might not be exactly zero.
 186      * This can be solved by also interpolating F, but
 187      * that comes at a cost.
 188      * A better hack is to remove the net force every
 189      * step, but that must be done at a higher level
 190      * since this routine doesn't see all atoms if running
 191      * in parallel. Don't know how important it is?  EL 990726
 192      */
 193 }
 194
 195
 196 real gather_energy_bsplines(struct gmx_pme_t *pme, real *grid,
 197                             pme_atomcomm_t *atc)
 198 {
 199     splinedata_t *spline;
 200     int     n, ithx, ithy, ithz, i0, j0, k0;
 201     int     index_x, index_xy;
 202     int *   idxptr;
 203     real    energy, pot, tx, ty, coefficient, gval;
 204     real    *thx, *thy, *thz;
 205     int     norder;
 206     int     order;
 207
 208     spline = &atc->spline[0];
 209
 210     order = pme->pme_order;
 211
 212     energy = 0;
 213     for (n = 0; (n < atc->n); n++)
 214     {
 215         coefficient      = atc->coefficient[n];
 216
 217         if (coefficient != 0)
 218         {
 219             idxptr = atc->idx[n];
 220             norder = n*order;
 221
 222             i0   = idxptr[XX];
 223             j0   = idxptr[YY];
 224             k0   = idxptr[ZZ];
 225
 226             /* Pointer arithmetic alert, next three statements */
 227             thx  = spline->theta[XX] + norder;
 228             thy  = spline->theta[YY] + norder;
 229             thz  = spline->theta[ZZ] + norder;
 230
 231             pot = 0;
 232             for (ithx = 0; (ithx < order); ithx++)
 233             {
 234                 index_x = (i0+ithx)*pme->pmegrid_ny*pme->pmegrid_nz;
 235                 tx      = thx[ithx];
 236
 237                 for (ithy = 0; (ithy < order); ithy++)
 238                 {
 239                     index_xy = index_x+(j0+ithy)*pme->pmegrid_nz;
 240                     ty       = thy[ithy];
 241
 242                     for (ithz = 0; (ithz < order); ithz++)
 243                     {
 244                         gval  = grid[index_xy+(k0+ithz)];
 245                         pot  += tx*ty*thz[ithz]*gval;
 246                     }
 247
 248                 }
 249             }
 250
 251             energy += pot*coefficient;
 252         }
 253     }
 254
 255     return energy;
 256 }