mirror of
https://github.com/smyalygames/FiniteVolumeGPU.git
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143 lines
4.9 KiB
Plaintext
143 lines
4.9 KiB
Plaintext
/*
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This OpenCL kernel implements the classical Lax-Friedrichs scheme
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for the shallow water equations, with edge fluxes.
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Copyright (C) 2016 SINTEF ICT
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "common.h"
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#include "SWECommon.h"
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/**
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* Computes the flux along the x axis for all faces
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*/
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__device__
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void computeFluxF(float Q[3][BLOCK_HEIGHT+2][BLOCK_WIDTH+2],
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float F[3][BLOCK_HEIGHT+2][BLOCK_WIDTH+2],
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const float g_, const float dx_, const float dt_) {
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//Compute fluxes along the x axis
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for (int j=threadIdx.y; j<BLOCK_HEIGHT+2; j+=BLOCK_HEIGHT) {
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for (int i=threadIdx.x; i<BLOCK_WIDTH+1; i+=BLOCK_WIDTH) {
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// Q at interface from the right and left
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const float3 Qp = make_float3(Q[0][j][i+1],
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Q[1][j][i+1],
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Q[2][j][i+1]);
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const float3 Qm = make_float3(Q[0][j][i],
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Q[1][j][i],
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Q[2][j][i]);
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// Computed flux
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const float3 flux = FORCE_1D_flux(Qm, Qp, g_, dx_, dt_);
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F[0][j][i] = flux.x;
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F[1][j][i] = flux.y;
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F[2][j][i] = flux.z;
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}
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}
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}
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/**
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* Computes the flux along the y axis for all faces
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*/
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__device__
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void computeFluxG(float Q[3][BLOCK_HEIGHT+2][BLOCK_WIDTH+2],
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float G[3][BLOCK_HEIGHT+2][BLOCK_WIDTH+2],
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const float g_, const float dy_, const float dt_) {
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//Compute fluxes along the y axis
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for (int j=threadIdx.y; j<BLOCK_HEIGHT+1; j+=BLOCK_HEIGHT) {
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for (int i=threadIdx.x; i<BLOCK_WIDTH+2; i+=BLOCK_WIDTH) {
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// Q at interface from the right and left
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// Note that we swap hu and hv
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const float3 Qp = make_float3(Q[0][j+1][i],
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Q[2][j+1][i],
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Q[1][j+1][i]);
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const float3 Qm = make_float3(Q[0][j][i],
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Q[2][j][i],
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Q[1][j][i]);
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// Computed flux
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// Note that we swap back
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const float3 flux = FORCE_1D_flux(Qm, Qp, g_, dy_, dt_);
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G[0][j][i] = flux.x;
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G[1][j][i] = flux.z;
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G[2][j][i] = flux.y;
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}
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}
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}
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extern "C" {
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__global__ void FORCEKernel(
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int nx_, int ny_,
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float dx_, float dy_, float dt_,
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float g_,
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int boundary_conditions_,
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//Input h^n
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float* h0_ptr_, int h0_pitch_,
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float* hu0_ptr_, int hu0_pitch_,
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float* hv0_ptr_, int hv0_pitch_,
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//Output h^{n+1}
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float* h1_ptr_, int h1_pitch_,
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float* hu1_ptr_, int hu1_pitch_,
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float* hv1_ptr_, int hv1_pitch_,
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//Output CFL
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float* cfl_) {
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const unsigned int w = BLOCK_WIDTH;
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const unsigned int h = BLOCK_HEIGHT;
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const unsigned int gc_x = 1;
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const unsigned int gc_y = 1;
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const unsigned int vars = 3;
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__shared__ float Q[vars][h+2*gc_y][w+2*gc_x];
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__shared__ float F[vars][h+2*gc_y][w+2*gc_x];
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//Read into shared memory
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readBlock<w, h, gc_x, gc_y, 1, 1>( h0_ptr_, h0_pitch_, Q[0], nx_, ny_, boundary_conditions_);
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readBlock<w, h, gc_x, gc_y, -1, 1>(hu0_ptr_, hu0_pitch_, Q[1], nx_, ny_, boundary_conditions_);
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readBlock<w, h, gc_x, gc_y, 1, -1>(hv0_ptr_, hv0_pitch_, Q[2], nx_, ny_, boundary_conditions_);
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__syncthreads();
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//Compute flux along x, and evolve
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computeFluxF(Q, F, g_, dx_, dt_);
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__syncthreads();
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evolveF<w, h, gc_x, gc_y, vars>(Q, F, dx_, dt_);
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__syncthreads();
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//Compute flux along y, and evolve
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computeFluxG(Q, F, g_, dy_, dt_);
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__syncthreads();
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evolveG<w, h, gc_x, gc_y, vars>(Q, F, dy_, dt_);
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__syncthreads();
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//Write to main memory
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writeBlock<w, h, gc_x, gc_y>( h1_ptr_, h1_pitch_, Q[0], nx_, ny_, 0, 1);
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writeBlock<w, h, gc_x, gc_y>(hu1_ptr_, hu1_pitch_, Q[1], nx_, ny_, 0, 1);
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writeBlock<w, h, gc_x, gc_y>(hv1_ptr_, hv1_pitch_, Q[2], nx_, ny_, 0, 1);
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//Compute the CFL for this block
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if (cfl_ != NULL) {
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writeCfl<w, h, gc_x, gc_y, vars>(Q, F[0], nx_, ny_, dx_, dy_, g_, cfl_);
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}
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}
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} // extern "C" |