mirror of
https://github.com/smyalygames/FiniteVolumeGPU.git
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225 lines
8.2 KiB
Plaintext
225 lines
8.2 KiB
Plaintext
/*
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This OpenCL kernel implements the Kurganov-Petrova numerical scheme
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for the shallow water equations, described in
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A. Kurganov & Guergana Petrova
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A Second-Order Well-Balanced Positivity Preserving Central-Upwind
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Scheme for the Saint-Venant System Communications in Mathematical
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Sciences, 5 (2007), 133-160.
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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.cu"
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#include "limiters.cu"
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#include "fluxes/CentralUpwind.cu"
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__device__
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void computeFluxF(float Q[3][BLOCK_HEIGHT+4][BLOCK_WIDTH+4],
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float Qx[3][BLOCK_HEIGHT+2][BLOCK_WIDTH+2],
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float F[3][BLOCK_HEIGHT+1][BLOCK_WIDTH+1],
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const float g_, const float dx_, const float dt_) {
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//Index of thread within block
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const int tx = get_local_id(0);
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const int ty = get_local_id(1);
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{
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int j=ty;
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const int l = j + 2; //Skip ghost cells
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for (int i=tx; i<BLOCK_WIDTH+1; i+=BLOCK_WIDTH) {
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const int k = i + 1;
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// Reconstruct point values of Q at the left and right hand side
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// of the cell for both the left (i) and right (i+1) cell
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const float3 Q_rl = make_float3(Q[0][l][k+1] - 0.5f*Qx[0][j][i+1],
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Q[1][l][k+1] - 0.5f*Qx[1][j][i+1],
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Q[2][l][k+1] - 0.5f*Qx[2][j][i+1]);
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const float3 Q_rr = make_float3(Q[0][l][k+1] + 0.5f*Qx[0][j][i+1],
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Q[1][l][k+1] + 0.5f*Qx[1][j][i+1],
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Q[2][l][k+1] + 0.5f*Qx[2][j][i+1]);
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const float3 Q_ll = make_float3(Q[0][l][k] - 0.5f*Qx[0][j][i],
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Q[1][l][k] - 0.5f*Qx[1][j][i],
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Q[2][l][k] - 0.5f*Qx[2][j][i]);
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const float3 Q_lr = make_float3(Q[0][l][k] + 0.5f*Qx[0][j][i],
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Q[1][l][k] + 0.5f*Qx[1][j][i],
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Q[2][l][k] + 0.5f*Qx[2][j][i]);
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//Evolve half a timestep (predictor step)
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const float3 Q_r_bar = Q_rl + dt_/(2.0f*dx_) * (F_func(Q_rl, g_) - F_func(Q_rr, g_));
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const float3 Q_l_bar = Q_lr + dt_/(2.0f*dx_) * (F_func(Q_ll, g_) - F_func(Q_lr, g_));
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// Compute flux based on prediction
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const float3 flux = CentralUpwindFlux(Q_l_bar, Q_r_bar, g_);
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//Write to shared memory
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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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__device__
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void computeFluxG(float Q[3][BLOCK_HEIGHT+4][BLOCK_WIDTH+4],
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float Qy[3][BLOCK_HEIGHT+2][BLOCK_WIDTH+2],
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float G[3][BLOCK_HEIGHT+1][BLOCK_WIDTH+1],
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const float g_, const float dy_, const float dt_) {
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//Index of thread within block
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const int tx = get_local_id(0);
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const int ty = get_local_id(1);
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for (int j=ty; j<BLOCK_HEIGHT+1; j+=BLOCK_HEIGHT) {
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const int l = j + 1;
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{
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int i=tx;
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const int k = i + 2; //Skip ghost cells
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// Reconstruct point values of Q at the left and right hand side
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// of the cell for both the left (i) and right (i+1) cell
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//NOte that hu and hv are swapped ("transposing" the domain)!
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const float3 Q_rl = make_float3(Q[0][l+1][k] - 0.5f*Qy[0][j+1][i],
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Q[2][l+1][k] - 0.5f*Qy[2][j+1][i],
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Q[1][l+1][k] - 0.5f*Qy[1][j+1][i]);
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const float3 Q_rr = make_float3(Q[0][l+1][k] + 0.5f*Qy[0][j+1][i],
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Q[2][l+1][k] + 0.5f*Qy[2][j+1][i],
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Q[1][l+1][k] + 0.5f*Qy[1][j+1][i]);
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const float3 Q_ll = make_float3(Q[0][l][k] - 0.5f*Qy[0][j][i],
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Q[2][l][k] - 0.5f*Qy[2][j][i],
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Q[1][l][k] - 0.5f*Qy[1][j][i]);
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const float3 Q_lr = make_float3(Q[0][l][k] + 0.5f*Qy[0][j][i],
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Q[2][l][k] + 0.5f*Qy[2][j][i],
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Q[1][l][k] + 0.5f*Qy[1][j][i]);
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//Evolve half a timestep (predictor step)
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const float3 Q_r_bar = Q_rl + dt_/(2.0f*dy_) * (F_func(Q_rl, g_) - F_func(Q_rr, g_));
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const float3 Q_l_bar = Q_lr + dt_/(2.0f*dy_) * (F_func(Q_ll, g_) - F_func(Q_lr, g_));
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// Compute flux based on prediction
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const float3 flux = CentralUpwindFlux(Q_l_bar, Q_r_bar, g_);
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//Write to shared memory
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//Note that we here swap hu and hv back to the original
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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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/**
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* This unsplit kernel computes the 2D numerical scheme with a TVD RK2 time integration scheme
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*/
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extern "C" {
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__global__ void KP07DimsplitKernel(
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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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float theta_,
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int step_,
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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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//Shared memory variables
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__shared__ float Q[3][BLOCK_HEIGHT+4][BLOCK_WIDTH+4];
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__shared__ float Qx[3][BLOCK_HEIGHT+2][BLOCK_WIDTH+2];
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__shared__ float F[3][BLOCK_HEIGHT+1][BLOCK_WIDTH+1];
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//Read into shared memory
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readBlock2(h0_ptr_, h0_pitch_,
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hu0_ptr_, hu0_pitch_,
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hv0_ptr_, hv0_pitch_,
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Q, nx_, ny_);
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__syncthreads();
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//Fix boundary conditions
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noFlowBoundary2(Q, nx_, ny_);
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__syncthreads();
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//Step 0 => evolve x first, then y
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if (step_ == 0) {
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//Compute fluxes along the x axis and evolve
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minmodSlopeX(Q, Qx, theta_);
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__syncthreads();
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computeFluxF(Q, Qx, F, g_, dx_, dt_);
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__syncthreads();
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evolveF2(Q, F, nx_, ny_, dx_, dt_);
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__syncthreads();
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//Set boundary conditions
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noFlowBoundary2(Q, nx_, ny_);
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__syncthreads();
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//Compute fluxes along the y axis and evolve
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minmodSlopeY(Q, Qx, theta_);
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__syncthreads();
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computeFluxG(Q, Qx, F, g_, dy_, dt_);
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__syncthreads();
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evolveG2(Q, F, nx_, ny_, dy_, dt_);
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__syncthreads();
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}
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//Step 1 => evolve y first, then x
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else {
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//Compute fluxes along the y axis and evolve
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minmodSlopeY(Q, Qx, theta_);
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__syncthreads();
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computeFluxG(Q, Qx, F, g_, dy_, dt_);
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__syncthreads();
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evolveG2(Q, F, nx_, ny_, dy_, dt_);
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__syncthreads();
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//Set boundary conditions
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noFlowBoundary2(Q, nx_, ny_);
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__syncthreads();
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//Compute fluxes along the x axis and evolve
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minmodSlopeX(Q, Qx, theta_);
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__syncthreads();
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computeFluxF(Q, Qx, F, g_, dx_, dt_);
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__syncthreads();
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evolveF2(Q, F, nx_, ny_, dx_, dt_);
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__syncthreads();
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}
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// Write to main memory for all internal cells
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writeBlock2(h1_ptr_, h1_pitch_,
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hu1_ptr_, hu1_pitch_,
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hv1_ptr_, hv1_pitch_,
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Q, nx_, ny_);
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}
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} // extern "C" |