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grid.cc
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Thu, Jul 10, 09:17

grid.cc
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/* -------------------------------------------------------------------------- */
#include "grid.hh"
/* -------------------------------------------------------------------------- */
#include <algorithm>
#if defined(_DEBUG_MPI)
#include <iomanip>
#endif
/* -------------------------------------------------------------------------- */
/* -------------------------------------------------------------------------- */
Grid::Grid(int m, int n) : m_m(m), m_n(n), m_storage(m * n) { clear(); }
/* -------------------------------------------------------------------------- */
Grid::~Grid() {
#if defined(_MPI)
MPI_Type_free(&column_t);
MPI_Type_free(&line_t);
#endif
}
/* -------------------------------------------------------------------------- */
void Grid::clear() { std::fill(m_storage.begin(), m_storage.end(), 0.); }
/* -------------------------------------------------------------------------- */
void Grid::resize(int m, int n) {
m_m = m;
m_n = n;
m_storage.resize(m * n);
}
/* -------------------------------------------------------------------------- */
int Grid::m() const { return m_m; }
int Grid::n() const { return m_n; }
/* -------------------------------------------------------------------------- */
#if defined(_MPI)
void Grid::initializeHaloCommunications(MPI_Comm & m_communicator,
const std::array<int, 2> & ghosts) {
std::array<int, 2> coords;
int prank;
MPI_Type_vector(m_m - ghosts[0], 1, m_n, MPI_FLOAT, &column_t);
MPI_Type_vector(1, m_n - ghosts[1], 1, MPI_FLOAT, &line_t);
MPI_Type_commit(&column_t);
MPI_Type_commit(&line_t);
MPI_Comm_rank(m_communicator, &prank);
MPI_Cart_coords(m_communicator, prank, coords.size(), coords.data());
// determining the rank of the neighbors
int left, right, top, bottom;
MPI_Cart_shift(m_communicator, 0, 1, &left, &right);
MPI_Cart_shift(m_communicator, 1, 1, &top, &bottom);
#if defined(_DEBUG_MPI)
static bool first = true;
if (first) {
int psize;
MPI_Comm_size(m_communicator, &psize);
for (int i = 0; i < psize; ++i) {
if (prank == i) {
std::cerr << prank << std::setw(7) << top << "\n"
<< prank << std::setw(8) << "^\n"
<< prank << std::setw(3) << left << " < . > " << right << "\n"
<< prank << std::setw(8) << "v\n"
<< prank << std::setw(7) << bottom << "\n\n";
}
MPI_Barrier(m_communicator);
}
first = false;
}
#endif
auto addr = [&](auto && i, auto && j) { return &(this->operator()(i, j)); };
MPI_Request * rrequest = m_requests.data();
MPI_Request * srequest = m_requests.data() + 4;
static int tag = 1;
/// preparing receives
{
auto send = addr(m_m - 2, 1);
auto recv = addr(0, 1);
MPI_Send_init(send, 1, line_t, bottom, tag, m_communicator, srequest);
MPI_Recv_init(recv, 1, line_t, top, tag, m_communicator, rrequest);
++rrequest;
++srequest;
++tag;
}
{
auto send = addr(1, m_n - 2);
auto recv = addr(1, 0);
MPI_Send_init(send, 1, column_t, right, tag, m_communicator, srequest);
MPI_Recv_init(recv, 1, column_t, left, tag, m_communicator, rrequest);
++rrequest;
++srequest;
++tag;
}
{
auto send = addr(1, 1);
auto recv = addr(m_m - 1, 1);
MPI_Send_init(send, 1, line_t, top, tag, m_communicator, srequest);
MPI_Recv_init(recv, 1, line_t, bottom, tag, m_communicator, rrequest);
++rrequest;
++srequest;
++tag;
}
{
auto send = addr(1, 1);
auto recv = addr(1, m_n - 1);
MPI_Send_init(send, 1, column_t, left, tag, m_communicator, srequest);
MPI_Recv_init(recv, 1, column_t, right, tag, m_communicator, rrequest);
++rrequest;
++srequest;
++tag;
}
}
#endif

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