CpuPlatform.cpp

/* -------------------------------------------------------------------------- *
 *                                   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) 2013-2014 Stanford University and the Authors.      *
 * Authors: Peter Eastman                                                     *
 * Contributors:                                                              *
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#include "CpuPlatform.h"
#include "CpuKernelFactory.h"
#include "CpuKernels.h"
#include "CpuSETTLE.h"
#include "ReferenceConstraints.h"
#include "openmm/internal/hardware.h"
#include <sstream>

using namespace OpenMM;
using namespace std;

#ifdef OPENMM_CPU_BUILDING_STATIC_LIBRARY
extern "C" void registerCpuPlatform() {
    if (CpuPlatform::isProcessorSupported())
        Platform::registerPlatform(new CpuPlatform());
}
#else
extern "C" OPENMM_EXPORT_CPU void registerPlatforms() {
    // Only register this platform if the CPU supports SSE 4.1.

    if (CpuPlatform::isProcessorSupported())
        Platform::registerPlatform(new CpuPlatform());
}
#endif

map<const ContextImpl*, CpuPlatform::PlatformData*> CpuPlatform::contextData;

CpuPlatform::CpuPlatform() {
    CpuKernelFactory* factory = new CpuKernelFactory();
    registerKernelFactory(CalcForcesAndEnergyKernel::Name(), factory);
    registerKernelFactory(CalcPeriodicTorsionForceKernel::Name(), factory);
    registerKernelFactory(CalcRBTorsionForceKernel::Name(), factory);
    registerKernelFactory(CalcNonbondedForceKernel::Name(), factory);
    registerKernelFactory(CalcCustomNonbondedForceKernel::Name(), factory);
    registerKernelFactory(CalcGBSAOBCForceKernel::Name(), factory);
    registerKernelFactory(IntegrateLangevinStepKernel::Name(), factory);
    platformProperties.push_back(CpuThreads());
    int threads = getNumProcessors();
    char* threadsEnv = getenv("OPENMM_CPU_THREADS");
    if (threadsEnv != NULL)
        stringstream(threadsEnv) >> threads;
    stringstream defaultThreads;
    defaultThreads << threads;
    setPropertyDefaultValue(CpuThreads(), defaultThreads.str());
}

const string& CpuPlatform::getPropertyValue(const Context& context, const string& property) const {
    const ContextImpl& impl = getContextImpl(context);
    const PlatformData& data = getPlatformData(impl);
    map<string, string>::const_iterator value = data.propertyValues.find(property);
    if (value != data.propertyValues.end())
        return value->second;
    return ReferencePlatform::getPropertyValue(context, property);
}

double CpuPlatform::getSpeed() const {
    return 10;
}

bool CpuPlatform::supportsDoublePrecision() const {
    return false;
}

bool CpuPlatform::isProcessorSupported() {
    // Make sure the CPU supports SSE 4.1.
    
    int cpuInfo[4];
    cpuid(cpuInfo, 0);
    if (cpuInfo[0] >= 1) {
        cpuid(cpuInfo, 1);
        return ((cpuInfo[2] & ((int) 1 << 19)) != 0);
    }
    return false;
}

void CpuPlatform::contextCreated(ContextImpl& context, const map<string, string>& properties) const {
    ReferencePlatform::contextCreated(context, properties);
    const string& threadsPropValue = (properties.find(CpuThreads()) == properties.end() ?
            getPropertyDefaultValue(CpuThreads()) : properties.find(CpuThreads())->second);
    int numThreads;
    stringstream(threadsPropValue) >> numThreads;
    PlatformData* data = new PlatformData(context.getSystem().getNumParticles(), numThreads);
    contextData[&context] = data;
    ReferenceConstraints& constraints = *(ReferenceConstraints*) reinterpret_cast<ReferencePlatform::PlatformData*>(context.getPlatformData())->constraints;
    if (constraints.settle != NULL) {
        CpuSETTLE* parallelSettle = new CpuSETTLE(context.getSystem(), *(ReferenceSETTLEAlgorithm*) constraints.settle, data->threads);
        delete constraints.settle;
        constraints.settle = parallelSettle;
    }
}

void CpuPlatform::contextDestroyed(ContextImpl& context) const {
    PlatformData* data = contextData[&context];
    delete data;
    contextData.erase(&context);
}

CpuPlatform::PlatformData& CpuPlatform::getPlatformData(ContextImpl& context) {
    return *contextData[&context];
}

const CpuPlatform::PlatformData& CpuPlatform::getPlatformData(const ContextImpl& context) {
    return *contextData[&context];
}

CpuPlatform::PlatformData::PlatformData(int numParticles, int numThreads) : posq(4*numParticles), threads(numThreads) {
    numThreads = threads.getNumThreads();
    threadForce.resize(numThreads);
    for (int i = 0; i < numThreads; i++)
        threadForce[i].resize(4*numParticles);
    isPeriodic = false;
    stringstream threadsProperty;
    threadsProperty << numThreads;
    propertyValues[CpuThreads()] = threadsProperty.str();
}