//===----------------------------------------------------------------------===// // // Part of CUDASTF in CUDA C++ Core Libraries, // under the Apache License v2.0 with LLVM Exceptions. // See https://llvm.org/LICENSE.txt for license information. // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception // SPDX-FileCopyrightText: Copyright (c) 2022-2024 NVIDIA CORPORATION & AFFILIATES. // //===----------------------------------------------------------------------===// #include #include using namespace cuda::experimental::stf; struct body { // mass double mass; // position double pos[3]; // speed double vel[3]; // acceleration double acc[3]; }; int main() { constexpr double kSofteningSquared = 1e-3; constexpr double kG = 6.67259e-11; size_t BODY_CNT = 4096; double dt = 0.1; size_t NITER = 25; context ctx; std::vector particles; particles.resize(BODY_CNT); // Initialize particles std::random_device rd; std::mt19937 gen(rd()); std::uniform_real_distribution<> dis(-1.0, 1.0); for (auto& p : particles) { p.mass = 1.0; p.pos[0] = dis(gen); p.pos[1] = dis(gen); p.pos[2] = dis(gen); p.vel[0] = dis(gen); p.vel[1] = dis(gen); p.vel[2] = dis(gen); p.acc[0] = 0.0; p.acc[1] = 0.0; p.acc[2] = 0.0; } auto h_particles = ctx.logical_data(make_slice(&particles[0], BODY_CNT)); auto fn = [dt](context ctx, logical_data> h_particles) { // Compute accelerations ctx.parallel_for(h_particles.shape(), h_particles.rw())->*[=] _CCCL_DEVICE __host__(size_t i, slice p) { double acc[3]; for (size_t k = 0; k < 3; k++) { acc[k] = p(i).acc[k]; } for (size_t j = 0; j < p.extent(0); j++) { if (i != j) { double d[3]; for (size_t k = 0; k < 3; k++) { d[k] = p(j).pos[k] - p(i).pos[k]; } double dist = d[0] * d[0] + d[1] * d[1] + d[2] * d[2] + kSofteningSquared; double dist_inv = 1.0 / sqrt(dist); for (size_t k = 0; k < 3; k++) { acc[k] += d[k] * kG * p(j).mass * dist_inv * dist_inv * dist_inv; } } } for (size_t k = 0; k < 3; k++) { p(i).acc[k] = acc[k]; } }; // Update velocity and positions ctx.parallel_for(h_particles.shape(), h_particles.rw())->*[=] __host__ __device__(size_t i, slice p) { for (size_t k = 0; k < 3; k++) { p(i).vel[k] += p(i).acc[k] * dt; } for (size_t k = 0; k < 3; k++) { p(i).pos[k] += p(i).vel[k] * dt; } for (size_t k = 0; k < 3; k++) { p(i).acc[k] = 0.0; } }; }; algorithm one_iter; for (size_t iter = 0; iter < NITER; iter++) { // fprintf(stderr, "ITER %ld\n", iter); one_iter.run_as_task(fn, ctx, h_particles.rw()); } ctx.finalize(); }