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lammps/lib/gpu/lj_gpu_kernel.h

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/***************************************************************************
lj_gpu_kernel.cu
-------------------
W. Michael Brown
Routines that actually perform the force computation
__________________________________________________________________________
This file is part of the LAMMPS GPU Library
__________________________________________________________________________
begin : Tue Aug 4 2009
copyright : (C) 2009 by W. Michael Brown
email : wmbrown@sandia.gov
***************************************************************************/
/* -----------------------------------------------------------------------
Copyright (2009) Sandia Corporation. Under the terms of Contract
DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
certain rights in this software. This software is distributed under
the GNU General Public License.
----------------------------------------------------------------------- */
#ifndef LJ_GPU_KERNEL
#define LJ_GPU_KERNEL
template<class numtyp, class acctyp>
__global__ void kernel_lj(const numtyp *special_lj, const int *dev_nbor,
const int *dev_ij, const int nbor_pitch, acctyp *ans,
size_t ans_pitch, const bool eflag,
const bool vflag, const int inum, const int nall) {
__shared__ numtyp sp_lj[4];
// ii indexes the two interacting particles in gi
int ii=threadIdx.x;
if (ii<4)
sp_lj[ii]=special_lj[ii];
ii+=INT_MUL(blockIdx.x,blockDim.x);
__syncthreads();
if (ii<inum) {
acctyp energy=(numtyp)0;
acctyp fx=(numtyp)0;
acctyp fy=(numtyp)0;
acctyp fz=(numtyp)0;
acctyp virial[6];
for (int i=0; i<6; i++)
virial[i]=(numtyp)0;
const int *nbor=dev_nbor+ii;
int i=*nbor;
nbor+=nbor_pitch;
int numj=*nbor;
nbor+=nbor_pitch;
const int *list=dev_ij+*nbor;
const int *list_end=list+numj;
numtyp ix=_x_<numtyp>(i,0);
numtyp iy=_x_<numtyp>(i,1);
numtyp iz=_x_<numtyp>(i,2);
int itype=_x_<numtyp>(i,3);
numtyp factor_lj;
for ( ; list<list_end; list++) {
int j=*list;
if (j < nall)
factor_lj = 1.0;
else {
factor_lj = sp_lj[j/nall];
j %= nall;
}
int jtype=_x_<numtyp>(j,3);
// Compute r12
numtyp delx = ix-_x_<numtyp>(j,0);
numtyp dely = iy-_x_<numtyp>(j,1);
numtyp delz = iz-_x_<numtyp>(j,2);
numtyp r2inv = delx*delx+dely*dely+delz*delz;
if (r2inv<_cutsq_<numtyp>(itype,jtype)) {
r2inv=(numtyp)1.0/r2inv;
numtyp r6inv =r2inv*r2inv*r2inv;
numtyp force =factor_lj*r2inv*r6inv*(_lj1_<numtyp>(itype,jtype).x*r6inv-
_lj1_<numtyp>(itype,jtype).y);
fx+=delx*force;
fy+=dely*force;
fz+=delz*force;
if (eflag) {
numtyp e=r6inv*(_lj3_<numtyp>(itype,jtype).x*r6inv-
_lj3_<numtyp>(itype,jtype).y);
energy+=factor_lj*(e-_offset_<numtyp>(1,1));
}
if (vflag) {
virial[0] += delx*delx*force;
virial[1] += dely*dely*force;
virial[2] += delz*delz*force;
virial[3] += delx*dely*force;
virial[4] += delx*delz*force;
virial[5] += dely*delz*force;
}
}
} // for nbor
// Store answers
acctyp *ap1=ans+ii;
if (eflag) {
*ap1=energy;
ap1+=ans_pitch;
}
if (vflag) {
for (int i=0; i<6; i++) {
*ap1=virial[i];
ap1+=ans_pitch;
}
}
*ap1=fx;
ap1+=ans_pitch;
*ap1=fy;
ap1+=ans_pitch;
*ap1=fz;
} // if ii
}
template<class numtyp, class acctyp>
__global__ void kernel_lj_fast(const numtyp *special_lj, const int *dev_nbor,
const int *dev_ij, const int nbor_pitch,
acctyp *ans, size_t ans_pitch,const bool eflag,
const bool vflag, const int inum,
const int nall) {
// ii indexes the two interacting particles in gi
int ii=threadIdx.x;
__shared__ numtyp sp_lj[4];
__shared__ numtyp cutsq[MAX_SHARED_TYPES*MAX_SHARED_TYPES];
__shared__ numtyp lj1[MAX_SHARED_TYPES*MAX_SHARED_TYPES];
__shared__ numtyp lj2[MAX_SHARED_TYPES*MAX_SHARED_TYPES];
__shared__ numtyp lj3[MAX_SHARED_TYPES*MAX_SHARED_TYPES];
__shared__ numtyp lj4[MAX_SHARED_TYPES*MAX_SHARED_TYPES];
__shared__ numtyp offset[MAX_SHARED_TYPES*MAX_SHARED_TYPES];
if (ii<4)
sp_lj[ii]=special_lj[ii];
if (ii<MAX_SHARED_TYPES*MAX_SHARED_TYPES) {
int itype=ii/MAX_SHARED_TYPES;
int jtype=ii%MAX_SHARED_TYPES;
cutsq[ii]=_cutsq_<numtyp>(itype,jtype);
lj1[ii]=_lj1_<numtyp>(itype,jtype).x;
lj2[ii]=_lj1_<numtyp>(itype,jtype).y;
if (eflag) {
lj3[ii]=_lj3_<numtyp>(itype,jtype).x;
lj4[ii]=_lj3_<numtyp>(itype,jtype).y;
offset[ii]=_offset_<numtyp>(itype,jtype);
}
}
ii+=INT_MUL(blockIdx.x,blockDim.x);
__syncthreads();
if (ii<inum) {
acctyp energy=(numtyp)0;
acctyp fx=(numtyp)0;
acctyp fy=(numtyp)0;
acctyp fz=(numtyp)0;
acctyp virial[6];
for (int i=0; i<6; i++)
virial[i]=(numtyp)0;
const int *nbor=dev_nbor+ii;
int i=*nbor;
nbor+=nbor_pitch;
int numj=*nbor;
nbor+=nbor_pitch;
const int *list=dev_ij+*nbor;
const int *list_end=list+numj;
numtyp ix=_x_<numtyp>(i,0);
numtyp iy=_x_<numtyp>(i,1);
numtyp iz=_x_<numtyp>(i,2);
int itype=INT_MUL(MAX_SHARED_TYPES,_x_<numtyp>(i,3));
numtyp factor_lj;
for ( ; list<list_end; list++) {
int j=*list;
if (j < nall)
factor_lj = 1.0;
else {
factor_lj = sp_lj[j/nall];
j %= nall;
}
int mtype=itype+_x_<numtyp>(j,3);
// Compute r12
numtyp delx = ix-_x_<numtyp>(j,0);
numtyp dely = iy-_x_<numtyp>(j,1);
numtyp delz = iz-_x_<numtyp>(j,2);
numtyp r2inv = delx*delx+dely*dely+delz*delz;
if (r2inv<cutsq[mtype]) {
r2inv=(numtyp)1.0/r2inv;
numtyp r6inv = r2inv*r2inv*r2inv;
numtyp force = factor_lj*r2inv*r6inv*(lj1[mtype]*r6inv-lj2[mtype]);
fx+=delx*force;
fy+=dely*force;
fz+=delz*force;
if (eflag) {
numtyp e=r6inv*(lj3[mtype]*r6inv-lj4[mtype]);
energy+=factor_lj*(e-offset[mtype]);
}
if (vflag) {
virial[0] += delx*delx*force;
virial[1] += dely*dely*force;
virial[2] += delz*delz*force;
virial[3] += delx*dely*force;
virial[4] += delx*delz*force;
virial[5] += dely*delz*force;
}
}
} // for nbor
// Store answers
acctyp *ap1=ans+ii;
if (eflag) {
*ap1=energy;
ap1+=ans_pitch;
}
if (vflag) {
for (int i=0; i<6; i++) {
*ap1=virial[i];
ap1+=ans_pitch;
}
}
*ap1=fx;
ap1+=ans_pitch;
*ap1=fy;
ap1+=ans_pitch;
*ap1=fz;
} // if ii
}
#endif
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