mirror of
https://github.com/smyalygames/FiniteVolumeGPU.git
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349 lines
9.5 KiB
C++
349 lines
9.5 KiB
C++
/*
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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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#pragma once
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/**
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* Float3 operators
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*/
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inline __device__ float3 operator*(const float a, const float3 b) {
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return make_float3(a*b.x, a*b.y, a*b.z);
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}
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inline __device__ float3 operator/(const float3 a, const float b) {
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return make_float3(a.x/b, a.y/b, a.z/b);
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}
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inline __device__ float3 operator-(const float3 a, const float3 b) {
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return make_float3(a.x-b.x, a.y-b.y, a.z-b.z);
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}
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inline __device__ float3 operator+(const float3 a, const float3 b) {
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return make_float3(a.x+b.x, a.y+b.y, a.z+b.z);
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}
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/**
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* Float4 operators
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*/
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inline __device__ float4 operator*(const float a, const float4 b) {
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return make_float4(a*b.x, a*b.y, a*b.z, a*b.w);
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}
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inline __device__ float4 operator/(const float4 a, const float b) {
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return make_float4(a.x/b, a.y/b, a.z/b, a.w/b);
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}
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inline __device__ float4 operator-(const float4 a, const float4 b) {
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return make_float4(a.x-b.x, a.y-b.y, a.z-b.z, a.w-b.w);
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}
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inline __device__ float4 operator+(const float4 a, const float4 b) {
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return make_float4(a.x+b.x, a.y+b.y, a.z+b.z, a.w+b.w);
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}
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inline __device__ __host__ float clamp(const float f, const float a, const float b) {
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return fmaxf(a, fminf(f, b));
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}
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inline __device__ __host__ int clamp(const int f, const int a, const int b) {
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return (f < b) ? ( (f > a) ? f : a) : b;
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}
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__device__ float desingularize(float x_, float eps_) {
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return copysign(1.0f, x_)*fmaxf(fabsf(x_), fminf(x_*x_/(2.0f*eps_)+0.5f*eps_, eps_));
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}
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/**
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* Reads a block of data with ghost cells
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*/
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template<int block_width, int block_height, int ghost_cells>
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inline __device__ void readBlock(float* ptr_, int pitch_,
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float shmem[block_height+2*ghost_cells][block_width+2*ghost_cells],
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const int nx_, const int ny_) {
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//Index of block within domain
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const int bx = blockDim.x * blockIdx.x;
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const int by = blockDim.y * blockIdx.y;
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const int gc_pad = 4;
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//Read into shared memory
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//Loop over all variables
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for (int j=threadIdx.y; j<block_height+2*ghost_cells; j+=block_height) {
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//const int l = min(by + j, ny_+2*ghost_cells-1);
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const int y = by + j;
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const int y_offset = ( (int) (y < gc_pad) - (int) (y >= ny_+2*ghost_cells-gc_pad) ) * (ny_+2*ghost_cells - 2*gc_pad);
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const int l = y + y_offset;
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float* row = (float*) ((char*) ptr_ + pitch_*l);
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for (int i=threadIdx.x; i<block_width+2*ghost_cells; i+=block_width) {
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//const int k = min(bx + i, nx_+2*ghost_cells-1);
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const int x = bx + i;
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const int gc_pad = 4;
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const int x_offset = ( (int) (x < gc_pad) - (int) (x >= nx_+2*ghost_cells-gc_pad) ) * (nx_+2*ghost_cells - 2*gc_pad);
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const int k = x + x_offset;
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shmem[j][i] = row[k];
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}
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}
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}
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/**
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* Writes a block of data to global memory for the shallow water equations.
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*/
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template<int block_width, int block_height, int ghost_cells>
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inline __device__ void writeBlock(float* ptr_, int pitch_,
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float shmem[block_height+2*ghost_cells][block_width+2*ghost_cells],
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const int width, const int height) {
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//Index of cell within domain
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const int ti = blockDim.x*blockIdx.x + threadIdx.x + ghost_cells;
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const int tj = blockDim.y*blockIdx.y + threadIdx.y + ghost_cells;
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//Only write internal cells
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if (ti < width+ghost_cells && tj < height+ghost_cells) {
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//Index of thread within block
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const int tx = threadIdx.x + ghost_cells;
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const int ty = threadIdx.y + ghost_cells;
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float* const row = (float*) ((char*) ptr_ + pitch_*tj);
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row[ti] = shmem[ty][tx];
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}
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}
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template<int block_width, int block_height, int ghost_cells, int scale_east_west=1, int scale_north_south=1>
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__device__ void noFlowBoundary(float Q[block_height+2*ghost_cells][block_width+2*ghost_cells], const int nx_, const int ny_) {
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for (int j=threadIdx.y; j<block_height+2*ghost_cells; j+= block_height) {
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const int i = threadIdx.x + ghost_cells;
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const int ti = blockDim.x*blockIdx.x + i;
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const int tj = blockDim.y*blockIdx.y + j;
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// West boundary
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if (ti == ghost_cells) {
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Q[j][i-1] = scale_east_west*Q[j][i];
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}
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if (ghost_cells >= 2 && ti == ghost_cells + 1) {
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Q[j][i-3] = scale_east_west*Q[j][i];
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}
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if (ghost_cells >= 3 && ti == ghost_cells + 2) {
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Q[j][i-5] = scale_east_west*Q[j][i];
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}
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if (ghost_cells >= 4 && ti == ghost_cells + 3) {
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Q[j][i-7] = scale_east_west*Q[j][i];
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}
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if (ghost_cells >= 5 && ti == ghost_cells + 4) {
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Q[j][i-9] = scale_east_west*Q[j][i];
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}
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// East boundary
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if (ti == nx_ + ghost_cells - 1) {
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Q[j][i+1] = scale_east_west*Q[j][i];
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}
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if (ghost_cells >= 2 && ti == nx_ + ghost_cells - 2) {
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Q[j][i+3] = scale_east_west*Q[j][i];
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}
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if (ghost_cells >= 3 && ti == nx_ + ghost_cells - 3) {
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Q[j][i+5] = scale_east_west*Q[j][i];
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}
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if (ghost_cells >= 4 && ti == nx_ + ghost_cells - 4) {
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Q[j][i+7] = scale_east_west*Q[j][i];
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}
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if (ghost_cells >= 5 && ti == nx_ + ghost_cells - 5) {
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Q[j][i+9] = scale_east_west*Q[j][i];
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}
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}
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for (int i=threadIdx.x; i<block_width+2*ghost_cells; i+= block_width) {
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const int j = threadIdx.y + ghost_cells;
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const int ti = blockDim.x*blockIdx.x + i;
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const int tj = blockDim.y*blockIdx.y + j;
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// South boundary
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if (tj == ghost_cells) {
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Q[j-1][i] = scale_north_south*Q[j][i];
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}
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if (ghost_cells >= 2 && tj == ghost_cells + 1) {
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Q[j-3][i] = scale_north_south*Q[j][i];
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}
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if (ghost_cells >= 3 && tj == ghost_cells + 2) {
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Q[j-5][i] = scale_north_south*Q[j][i];
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}
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if (ghost_cells >= 4 && tj == ghost_cells + 3) {
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Q[j-7][i] = scale_north_south*Q[j][i];
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}
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if (ghost_cells >= 5 && tj == ghost_cells + 4) {
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Q[j-9][i] = scale_north_south*Q[j][i];
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}
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// North boundary
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if (tj == ny_ + ghost_cells - 1) {
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Q[j+1][i] = scale_north_south*Q[j][i];
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}
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if (ghost_cells >= 2 && tj == ny_ + ghost_cells - 2) {
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Q[j+3][i] = scale_north_south*Q[j][i];
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}
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if (ghost_cells >= 3 && tj == ny_ + ghost_cells - 3) {
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Q[j+5][i] = scale_north_south*Q[j][i];
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}
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if (ghost_cells >= 4 && tj == ny_ + ghost_cells - 4) {
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Q[j+7][i] = scale_north_south*Q[j][i];
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}
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if (ghost_cells >= 5 && tj == ny_ + ghost_cells - 5) {
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Q[j+9][i] = scale_north_south*Q[j][i];
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}
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}
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}
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template<int block_width, int block_height, int ghost_cells, int vars>
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__device__ void evolveF(float Q[vars][block_height+2*ghost_cells][block_width+2*ghost_cells],
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float F[vars][block_height+2*ghost_cells][block_width+2*ghost_cells],
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const float dx_, const float dt_) {
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for (int var=0; var < vars; ++var) {
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for (int j=threadIdx.y; j<block_height+2*ghost_cells; j+=block_height) {
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for (int i=threadIdx.x+1; i<block_width+2*ghost_cells; i+=block_width) {
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Q[var][j][i] = Q[var][j][i] + (F[var][j][i-1] - F[var][j][i]) * dt_ / dx_;
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}
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}
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}
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}
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/**
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* Evolves the solution in time along the y axis (dimensional splitting)
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*/
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template<int block_width, int block_height, int ghost_cells, int vars>
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__device__ void evolveG(float Q[vars][block_height+2*ghost_cells][block_width+2*ghost_cells],
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float G[vars][block_height+2*ghost_cells][block_width+2*ghost_cells],
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const float dy_, const float dt_) {
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for (int var=0; var < vars; ++var) {
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for (int j=threadIdx.y+1; j<block_height+2*ghost_cells; j+=block_height) {
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for (int i=threadIdx.x; i<block_width+2*ghost_cells; i+=block_width) {
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Q[var][j][i] = Q[var][j][i] + (G[var][j-1][i] - G[var][j][i]) * dt_ / dy_;
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}
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}
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}
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}
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/**
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* Helper function for debugging etc.
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*/
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template<int shmem_width, int shmem_height, int vars>
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__device__ void memset(float Q[vars][shmem_height][shmem_width], float value) {
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for (int k=0; k<vars; ++k) {
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for (int j=threadIdx.y; j<shmem_height; ++j) {
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for (int i=threadIdx.x; i<shmem_width; ++i) {
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Q[k][j][i] = value;
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}
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}
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}
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}
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