/* -------------------------------------------------------------------------- *
* OpenMM *
* -------------------------------------------------------------------------- *
* This is part of the OpenMM molecular simulation toolkit originating from *
* Simbios, the NIH National Center for Physics-Based Simulation of *
* Biological Structures at Stanford, funded under the NIH Roadmap for *
* Medical Research, grant U54 GM072970. See https://simtk.org. *
* *
* Portions copyright (c) 2009 Stanford University and the Authors. *
* Authors: Scott Le Grand, Peter Eastman *
* Contributors: *
* *
* This program is free software: you can redistribute it and/or modify *
* it under the terms of the GNU Lesser General Public License as published *
* by the Free Software Foundation, either version 3 of the License, or *
* (at your option) any later version. *
* *
* This program is distributed in the hope that it will be useful, *
* but WITHOUT ANY WARRANTY; without even the implied warranty of *
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
* GNU Lesser General Public License for more details. *
* *
* You should have received a copy of the GNU Lesser General Public License *
* along with this program. If not, see . *
* -------------------------------------------------------------------------- */
/**
* This file contains the kernels for evalauating nonbonded forces. It is included
* several times in kCalculateCustomNonbondedForces.cu with different #defines to generate
* different versions of the kernels.
*/
__global__ void METHOD_NAME(kCalculateCustomNonbonded, Forces_kernel)(unsigned int* workUnit)
{
extern __shared__ float stack[];
Atom* sA = (Atom*) &stack[MAX_STACK_SIZE*blockDim.x];
unsigned int totalWarps = cSim.nonbond_blocks*cSim.nonbond_threads_per_block/GRID;
unsigned int warp = (blockIdx.x*blockDim.x+threadIdx.x)/GRID;
unsigned int numWorkUnits = cSim.pInteractionCount[0];
unsigned int pos = warp*numWorkUnits/totalWarps;
unsigned int end = (warp+1)*numWorkUnits/totalWarps;
#ifdef USE_CUTOFF
float3* tempBuffer = (float3*) &sA[cSim.nonbond_threads_per_block];
#endif
unsigned int lasty = 0xFFFFFFFF;
while (pos < end)
{
// Extract cell coordinates from appropriate work unit
unsigned int x = workUnit[pos];
unsigned int y = ((x >> 2) & 0x7fff) << GRIDBITS;
bool bExclusionFlag = (x & 0x1);
x = (x >> 17) << GRIDBITS;
float4 apos; // Local atom x, y, z, q
float3 af; // Local atom fx, fy, fz
unsigned int tgx = threadIdx.x & (GRID - 1);
unsigned int tbx = threadIdx.x - tgx;
unsigned int tj = tgx;
Atom* psA = &sA[tbx];
unsigned int i = x + tgx;
apos = cSim.pPosq[i];
float4 params = make_float4(0,0,0,0);
af.x = 0.0f;
af.y = 0.0f;
af.z = 0.0f;
if (x == y) // Handle diagonals uniquely at 50% efficiency
{
// Read fixed atom data into registers and GRF
sA[threadIdx.x].x = apos.x;
sA[threadIdx.x].y = apos.y;
sA[threadIdx.x].z = apos.z;
sA[threadIdx.x].params = params;
if (!bExclusionFlag)
{
for (unsigned int j = 0; j < GRID; j++)
{
float4 combinedParams;
float dx = psA[j].x - apos.x;
float dy = psA[j].y - apos.y;
float dz = psA[j].z - apos.z;
#ifdef USE_PERIODIC
dx -= floor(dx/cSim.periodicBoxSizeX+0.5f)*cSim.periodicBoxSizeX;
dy -= floor(dy/cSim.periodicBoxSizeY+0.5f)*cSim.periodicBoxSizeY;
dz -= floor(dz/cSim.periodicBoxSizeZ+0.5f)*cSim.periodicBoxSizeZ;
#endif
float r = sqrt(dx*dx + dy*dy + dz*dz);
float invR = 1.0f/r;
float dEdR = -kEvaluateExpression_kernel(&forceExp, &stack[MAX_STACK_SIZE*threadIdx.x], r, combinedParams, combinedParams)*invR;
#ifdef USE_CUTOFF
if (r > cSim.nonbondedCutoff)
{
dEdR = 0.0f;
}
#endif
dx *= dEdR;
dy *= dEdR;
dz *= dEdR;
af.x -= dx;
af.y -= dy;
af.z -= dz;
}
}
else // bExclusion
{
unsigned int xi = x>>GRIDBITS;
unsigned int cell = xi+xi*cSim.paddedNumberOfAtoms/GRID-xi*(xi+1)/2;
unsigned int excl = cSim.pExclusion[cSim.pExclusionIndex[cell]+tgx];
for (unsigned int j = 0; j < GRID; j++)
{
float4 combinedParams;
float dx = psA[j].x - apos.x;
float dy = psA[j].y - apos.y;
float dz = psA[j].z - apos.z;
#ifdef USE_PERIODIC
dx -= floor(dx/cSim.periodicBoxSizeX+0.5f)*cSim.periodicBoxSizeX;
dy -= floor(dy/cSim.periodicBoxSizeY+0.5f)*cSim.periodicBoxSizeY;
dz -= floor(dz/cSim.periodicBoxSizeZ+0.5f)*cSim.periodicBoxSizeZ;
#endif
float r = sqrt(dx*dx + dy*dy + dz*dz);
float invR = 1.0f/r;
float dEdR = -kEvaluateExpression_kernel(&forceExp, &stack[MAX_STACK_SIZE*threadIdx.x], r, combinedParams, combinedParams)*invR;
#ifdef USE_CUTOFF
if (!(excl & 0x1) || r > cSim.nonbondedCutoff)
#else
if (!(excl & 0x1))
#endif
{
dEdR = 0.0f;
}
dx *= dEdR;
dy *= dEdR;
dz *= dEdR;
af.x -= dx;
af.y -= dy;
af.z -= dz;
excl >>= 1;
}
}
// Write results
float4 of;
#ifdef USE_OUTPUT_BUFFER_PER_WARP
unsigned int offset = x + tgx + warp*cSim.stride;
of = cSim.pForce4a[offset];
of.x += af.x;
of.y += af.y;
of.z += af.z;
cSim.pForce4a[offset] = of;
#else
of.x = af.x;
of.y = af.y;
of.z = af.z;
of.w = 0.0f;
unsigned int offset = x + tgx + (x >> GRIDBITS) * cSim.stride;
cSim.pForce4a[offset] = of;
#endif
}
else // 100% utilization
{
// Read fixed atom data into registers and GRF
if (lasty != y)
{
unsigned int j = y + tgx;
float4 temp = cSim.pPosq[j];
sA[threadIdx.x].x = temp.x;
sA[threadIdx.x].y = temp.y;
sA[threadIdx.x].z = temp.z;
sA[threadIdx.x].params = make_float4(0,0,0,0);;
}
sA[threadIdx.x].fx = 0.0f;
sA[threadIdx.x].fy = 0.0f;
sA[threadIdx.x].fz = 0.0f;
if (!bExclusionFlag)
{
#ifdef USE_CUTOFF
unsigned int flags = cSim.pInteractionFlag[pos];
if (flags == 0)
{
// No interactions in this block.
}
else if (flags == 0xFFFFFFFF)
#endif
{
// Compute all interactions within this block.
for (unsigned int j = 0; j < GRID; j++)
{
float4 combinedParams;
float dx = psA[tj].x - apos.x;
float dy = psA[tj].y - apos.y;
float dz = psA[tj].z - apos.z;
#ifdef USE_PERIODIC
dx -= floor(dx/cSim.periodicBoxSizeX+0.5f)*cSim.periodicBoxSizeX;
dy -= floor(dy/cSim.periodicBoxSizeY+0.5f)*cSim.periodicBoxSizeY;
dz -= floor(dz/cSim.periodicBoxSizeZ+0.5f)*cSim.periodicBoxSizeZ;
#endif
float r = sqrt(dx*dx + dy*dy + dz*dz);
float invR = 1.0f/r;
float dEdR = -kEvaluateExpression_kernel(&forceExp, &stack[MAX_STACK_SIZE*threadIdx.x], r, combinedParams, combinedParams)*invR;
#ifdef USE_CUTOFF
if (r > cSim.nonbondedCutoff)
{
dEdR = 0.0f;
}
#endif
dx *= dEdR;
dy *= dEdR;
dz *= dEdR;
af.x -= dx;
af.y -= dy;
af.z -= dz;
psA[tj].fx += dx;
psA[tj].fy += dy;
psA[tj].fz += dz;
tj = (tj + 1) & (GRID - 1);
}
}
#ifdef USE_CUTOFF
else
{
// Compute only a subset of the interactions in this block.
for (unsigned int j = 0; j < GRID; j++)
{
if ((flags&(1< cSim.nonbondedCutoff)
{
dEdR = 0.0f;
}
#endif
dx *= dEdR;
dy *= dEdR;
dz *= dEdR;
af.x -= dx;
af.y -= dy;
af.z -= dz;
tempBuffer[threadIdx.x].x = dx;
tempBuffer[threadIdx.x].y = dy;
tempBuffer[threadIdx.x].z = dz;
// Sum the forces on atom j.
if (tgx % 2 == 0)
{
tempBuffer[threadIdx.x].x += tempBuffer[threadIdx.x+1].x;
tempBuffer[threadIdx.x].y += tempBuffer[threadIdx.x+1].y;
tempBuffer[threadIdx.x].z += tempBuffer[threadIdx.x+1].z;
}
if (tgx % 4 == 0)
{
tempBuffer[threadIdx.x].x += tempBuffer[threadIdx.x+2].x;
tempBuffer[threadIdx.x].y += tempBuffer[threadIdx.x+2].y;
tempBuffer[threadIdx.x].z += tempBuffer[threadIdx.x+2].z;
}
if (tgx % 8 == 0)
{
tempBuffer[threadIdx.x].x += tempBuffer[threadIdx.x+4].x;
tempBuffer[threadIdx.x].y += tempBuffer[threadIdx.x+4].y;
tempBuffer[threadIdx.x].z += tempBuffer[threadIdx.x+4].z;
}
if (tgx % 16 == 0)
{
tempBuffer[threadIdx.x].x += tempBuffer[threadIdx.x+8].x;
tempBuffer[threadIdx.x].y += tempBuffer[threadIdx.x+8].y;
tempBuffer[threadIdx.x].z += tempBuffer[threadIdx.x+8].z;
}
if (tgx == 0)
{
psA[j].fx += tempBuffer[threadIdx.x].x + tempBuffer[threadIdx.x+16].x;
psA[j].fy += tempBuffer[threadIdx.x].y + tempBuffer[threadIdx.x+16].y;
psA[j].fz += tempBuffer[threadIdx.x].z + tempBuffer[threadIdx.x+16].z;
}
}
}
}
#endif
}
else // bExclusion
{
// Read fixed atom data into registers and GRF
unsigned int xi = x>>GRIDBITS;
unsigned int yi = y>>GRIDBITS;
unsigned int cell = xi+yi*cSim.paddedNumberOfAtoms/GRID-yi*(yi+1)/2;
unsigned int excl = cSim.pExclusion[cSim.pExclusionIndex[cell]+tgx];
excl = (excl >> tgx) | (excl << (GRID - tgx));
for (unsigned int j = 0; j < GRID; j++)
{
float4 combinedParams;
float dx = psA[tj].x - apos.x;
float dy = psA[tj].y - apos.y;
float dz = psA[tj].z - apos.z;
#ifdef USE_PERIODIC
dx -= floor(dx/cSim.periodicBoxSizeX+0.5f)*cSim.periodicBoxSizeX;
dy -= floor(dy/cSim.periodicBoxSizeY+0.5f)*cSim.periodicBoxSizeY;
dz -= floor(dz/cSim.periodicBoxSizeZ+0.5f)*cSim.periodicBoxSizeZ;
#endif
float r = sqrt(dx*dx + dy*dy + dz*dz);
float invR = 1.0f/r;
float dEdR = -kEvaluateExpression_kernel(&forceExp, &stack[MAX_STACK_SIZE*threadIdx.x], r, combinedParams, combinedParams)*invR;
#ifdef USE_CUTOFF
if (!(excl & 0x1) || r > cSim.nonbondedCutoff)
#else
if (!(excl & 0x1))
#endif
{
dEdR = 0.0f;
}
dx *= dEdR;
dy *= dEdR;
dz *= dEdR;
af.x -= dx;
af.y -= dy;
af.z -= dz;
psA[tj].fx += dx;
psA[tj].fy += dy;
psA[tj].fz += dz;
excl >>= 1;
tj = (tj + 1) & (GRID - 1);
}
}
// Write results
float4 of;
#ifdef USE_OUTPUT_BUFFER_PER_WARP
unsigned int offset = x + tgx + warp*cSim.stride;
of = cSim.pForce4a[offset];
of.x += af.x;
of.y += af.y;
of.z += af.z;
cSim.pForce4a[offset] = of;
offset = y + tgx + warp*cSim.stride;
of = cSim.pForce4a[offset];
of.x += sA[threadIdx.x].fx;
of.y += sA[threadIdx.x].fy;
of.z += sA[threadIdx.x].fz;
cSim.pForce4a[offset] = of;
#else
of.x = af.x;
of.y = af.y;
of.z = af.z;
of.w = 0.0f;
unsigned int offset = x + tgx + (y >> GRIDBITS) * cSim.stride;
cSim.pForce4a[offset] = of;
of.x = sA[threadIdx.x].fx;
of.y = sA[threadIdx.x].fy;
of.z = sA[threadIdx.x].fz;
offset = y + tgx + (x >> GRIDBITS) * cSim.stride;
cSim.pForce4a[offset] = of;
#endif
lasty = y;
}
pos++;
}
}