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lammps/lib/gpu/pppm.cu
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pppm.cu
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// **************************************************************************
// pppm.cu
// -------------------
// W. Michael Brown (ORNL)
//
// Device code for PPPM acceleration
//
// __________________________________________________________________________
// This file is part of the LAMMPS Accelerator Library (LAMMPS_AL)
// __________________________________________________________________________
//
// begin :
// email : brownw@ornl.gov
// ***************************************************************************/
#ifdef NV_KERNEL
#include "preprocessor.h"
texture<float4> pos_tex;
texture<float> q_tex;
#ifndef _DOUBLE_DOUBLE
__inline float4 fetch_pos(const int& i, const float4 *pos)
{ return tex1Dfetch(pos_tex, i); }
__inline float fetch_q(const int& i, const float *q)
{ return tex1Dfetch(q_tex, i); }
#endif
// Allow PPPM to compile without atomics for NVIDIA 1.0 cards, error
// generated at runtime with use of pppm/gpu
#if (__CUDA_ARCH__ < 110)
#define atomicAdd(x,y) *(x)+=0
#endif
#else
#pragma OPENCL EXTENSION cl_khr_global_int32_base_atomics: enable
#endif
// Number of threads per pencil for charge spread
#define PENCIL_SIZE MEM_THREADS
// Number of pencils per block for charge spread
#define BLOCK_PENCILS (PPPM_BLOCK_1D/PENCIL_SIZE)
__kernel void particle_map(__global numtyp4 *x_, __global numtyp *q_,
const grdtyp delvolinv, const int nlocal,
__global int *counts, __global grdtyp4 *ans,
const grdtyp b_lo_x, const grdtyp b_lo_y,
const grdtyp b_lo_z, const grdtyp delxinv,
const grdtyp delyinv, const grdtyp delzinv,
const int nlocal_x, const int nlocal_y,
const int nlocal_z, const int atom_stride,
const int max_atoms, __global int *error) {
// ii indexes the two interacting particles in gi
int ii=GLOBAL_ID_X;
// Resequence the atom indices to avoid collisions during atomic ops
int nthreads=GLOBAL_SIZE_X;
ii=mul24(ii,PPPM_BLOCK_1D);
ii-=(ii/nthreads)*(nthreads-1);
int nx,ny,nz;
if (ii<nlocal) {
numtyp4 p=fetch_pos(ii,x_);
grdtyp4 delta;
delta.w=delvolinv*fetch_q(ii,q_);
if (delta.w!=(grdtyp)0.0) {
delta.x=(p.x-b_lo_x)*delxinv;
nx=delta.x;
delta.y=(p.y-b_lo_y)*delyinv;
ny=delta.y;
delta.z=(p.z-b_lo_z)*delzinv;
nz=delta.z;
if (delta.x<(grdtyp)0 || delta.y<(grdtyp)0 || delta.z<(grdtyp)0 ||
nx>=nlocal_x || ny>=nlocal_y || nz>=nlocal_z)
*error=1;
else {
delta.x=nx+(grdtyp)0.5-delta.x;
delta.y=ny+(grdtyp)0.5-delta.y;
delta.z=nz+(grdtyp)0.5-delta.z;
int i=nz*nlocal_y*nlocal_x+ny*nlocal_x+nx;
int old=atom_add(counts+i, 1);
if (old>=max_atoms) {
*error=2;
atom_add(counts+i, -1);
} else
ans[atom_stride*old+i]=delta;
}
}
}
}
/* --------------------------- */
__kernel void make_rho(__global int *counts, __global grdtyp4 *atoms,
__global grdtyp *brick, __global grdtyp *_rho_coeff,
const int atom_stride, const int npts_x,
const int npts_y, const int npts_z, const int nlocal_x,
const int nlocal_y, const int nlocal_z,
const int order_m_1, const int order, const int order2) {
__local grdtyp rho_coeff[PPPM_MAX_SPLINE*PPPM_MAX_SPLINE];
__local grdtyp front[BLOCK_PENCILS][PENCIL_SIZE+PPPM_MAX_SPLINE];
__local grdtyp ans[PPPM_MAX_SPLINE][PPPM_BLOCK_1D];
int tid=THREAD_ID_X;
if (tid<order2+order)
rho_coeff[tid]=_rho_coeff[tid];
int pid=tid/PENCIL_SIZE;
int fid=tid%PENCIL_SIZE;
int fid_halo=PENCIL_SIZE+fid;
if (fid<order)
front[pid][fid_halo]=(grdtyp)0.0;
__syncthreads();
int bt=BLOCK_ID_X*BLOCK_PENCILS+pid;
int ny=bt%npts_y;
int nz=bt/npts_y;
int y_start=0;
int z_start=0;
int y_stop=order;
int z_stop=order;
if (ny<order_m_1)
y_start=order_m_1-ny;
if (nz<order_m_1)
z_start=order_m_1-nz;
if (ny>=nlocal_y)
y_stop-=ny-nlocal_y+1;
if (nz>=nlocal_z)
z_stop-=nz-nlocal_z+1;
int z_stride=mul24(nlocal_x,nlocal_y);
int loop_count=npts_x/PENCIL_SIZE+1;
int nx=fid;
int pt=mul24(nz,mul24(npts_y,npts_x))+mul24(ny,npts_x)+nx;
for (int i=0 ; i<loop_count; i++) {
for (int n=0; n<order; n++)
ans[n][tid]=(grdtyp)0.0;
if (nx<nlocal_x && nz<npts_z) {
int z_pos=mul24(nz+z_start-order_m_1,z_stride);
for (int m=z_start; m<z_stop; m++) {
int y_pos=mul24(ny+y_start-order_m_1,nlocal_x);
for (int l=y_start; l<y_stop; l++) {
int pos=z_pos+y_pos+nx;
int natoms=mul24(counts[pos],atom_stride);
for (int row=pos; row<natoms; row+=atom_stride) {
grdtyp4 delta=atoms[row];
grdtyp rho1d_1=(grdtyp)0.0;
grdtyp rho1d_2=(grdtyp)0.0;
for (int k=order2+order-1; k > -1; k-=order) {
rho1d_1=rho_coeff[k-l]+rho1d_1*delta.y;
rho1d_2=rho_coeff[k-m]+rho1d_2*delta.z;
}
delta.w*=rho1d_1*rho1d_2;
for (int n=0; n<order; n++) {
grdtyp rho1d_0=(grdtyp)0.0;
for (int k=order2+n; k>=n; k-=order)
rho1d_0=rho_coeff[k]+rho1d_0*delta.x;
ans[n][tid]+=delta.w*rho1d_0;
}
}
y_pos+=nlocal_x;
}
z_pos+=z_stride;
}
}
__syncthreads();
if (fid<order) {
front[pid][fid]=front[pid][fid_halo];
front[pid][fid_halo]=(grdtyp)0.0;
} else
front[pid][fid]=(grdtyp)0.0;
for (int n=0; n<order; n++) {
front[pid][fid+n]+=ans[n][tid];
__syncthreads();
}
if (nx<npts_x && nz<npts_z)
brick[pt]=front[pid][fid];
pt+=PENCIL_SIZE;
nx+=PENCIL_SIZE;
}
}
__kernel void interp(__global numtyp4 *x_, __global numtyp *q_,
const int nlocal, __global grdtyp4 *brick,
__global grdtyp *_rho_coeff, const int npts_x,
const int npts_yx, const grdtyp b_lo_x,
const grdtyp b_lo_y, const grdtyp b_lo_z,
const grdtyp delxinv, const grdtyp delyinv,
const grdtyp delzinv, const int order,
const int order2, const grdtyp qqrd2e_scale,
__global acctyp4 *ans) {
__local grdtyp rho_coeff[PPPM_MAX_SPLINE*PPPM_MAX_SPLINE];
__local grdtyp rho1d_0[PPPM_MAX_SPLINE][PPPM_BLOCK_1D];
__local grdtyp rho1d_1[PPPM_MAX_SPLINE][PPPM_BLOCK_1D];
int tid=THREAD_ID_X;
if (tid<order2+order)
rho_coeff[tid]=_rho_coeff[tid];
__syncthreads();
int ii=tid+BLOCK_ID_X*BLOCK_SIZE_X;
int nx,ny,nz;
grdtyp tx,ty,tz;
if (ii<nlocal) {
numtyp4 p=fetch_pos(ii,x_);
grdtyp qs=qqrd2e_scale*fetch_q(ii,q_);
acctyp4 ek;
ek.x=(acctyp)0.0;
ek.y=(acctyp)0.0;
ek.z=(acctyp)0.0;
if (qs!=(grdtyp)0.0) {
tx=(p.x-b_lo_x)*delxinv;
nx=tx;
ty=(p.y-b_lo_y)*delyinv;
ny=ty;
tz=(p.z-b_lo_z)*delzinv;
nz=tz;
grdtyp dx=nx+(grdtyp)0.5-tx;
grdtyp dy=ny+(grdtyp)0.5-ty;
grdtyp dz=nz+(grdtyp)0.5-tz;
for (int k=0; k<order; k++) {
rho1d_0[k][tid]=(grdtyp)0.0;
rho1d_1[k][tid]=(grdtyp)0.0;
for (int l=order2+k; l>=k; l-=order) {
rho1d_0[k][tid]=rho_coeff[l]+rho1d_0[k][tid]*dx;
rho1d_1[k][tid]=rho_coeff[l]+rho1d_1[k][tid]*dy;
}
}
int mz=mul24(nz,npts_yx)+nx;
for (int n=0; n<order; n++) {
grdtyp rho1d_2=(grdtyp)0.0;
for (int k=order2+n; k>=n; k-=order)
rho1d_2=rho_coeff[k]+rho1d_2*dz;
grdtyp z0=qs*rho1d_2;
int my=mz+mul24(ny,npts_x);
for (int m=0; m<order; m++) {
grdtyp y0=z0*rho1d_1[m][tid];
for (int l=0; l<order; l++) {
grdtyp x0=y0*rho1d_0[l][tid];
grdtyp4 el=brick[my+l];
ek.x-=x0*el.x;
ek.y-=x0*el.y;
ek.z-=x0*el.z;
}
my+=npts_x;
}
mz+=npts_yx;
}
}
ans[ii]=ek;
}
}
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