Homec4science
Diffusion Poisson code for introduction to parallelism (implementation/c++) Browse

rSCINTROPARALLEL/dumpers.cc
f961b05e640cimplementation/c++

Last Change
Raw File

dumpers.cc
View Options

/* -------------------------------------------------------------------------- */
#include "dumpers.hh"
#include "grid.hh"
/* -------------------------------------------------------------------------- */
#include <array>
#include <fstream>
#include <iomanip>
#include <sstream>
/* -------------------------------------------------------------------------- */
/* -------------------------------------------------------------------------- */
void Dumper::set_min(float min) { m_min = min; }
void Dumper::set_max(float max) { m_max = max; }
float Dumper::min() const { return m_min; }
float Dumper::max() const { return m_max; }
/* -------------------------------------------------------------------------- */
void DumperASCII::dump(int step) {
std::ofstream fout;
std::stringstream sfilename;
sfilename << "out_" << std::setfill('0') << std::setw(5) << step << ".pgm";
fout.open(sfilename.str());
int m = m_grid.m();
int n = m_grid.n();
fout << "P2" << std::endl << "# CREATOR: Poisson program" << std::endl;
fout << m << " " << n << std::endl;
fout << 255 << std::endl;
for (int i = 0; i < m; i++) {
for (int j = 0; j < n; j++) {
int v = 255. * (m_grid(i, j) - m_min) / (m_max - m_min);
v = std::min(v, 255);
fout << v << std::endl;
}
}
}
/* -------------------------------------------------------------------------- */
void DumperBinary::dump(int step) {
std::stringstream sfilename;
int prank, psize;
MPI_Comm_rank(m_communicator, &prank);
MPI_Comm_size(m_communicator, &psize);
sfilename << "out_" << std::setfill('0') << std::setw(5) << step << ".bmp";
int h = m_grid.m();
int w = m_grid.n();
int start = 0;
// removing the ghosts from the height
if (psize > 1) {
h = (prank == 0 || prank == psize - 1 ? h - 1 : h - 2);
start = (prank == 0 ? 0 : 1);
}
// Gathering the size of every processors, this could be done as in the
// constructor of the Simulation instead
std::vector<int> size_per_proc(psize);
MPI_Allgather(&h, 1, MPI_INT, size_per_proc.data(), 1, MPI_INT,
m_communicator);
// determining the local offset
int offset_h = 0;
for (int i = 0; i < prank; ++i) {
offset_h += size_per_proc[i];
}
int total_h = offset_h;
for (int i = prank; i < psize; ++i) {
total_h += size_per_proc[i];
}
int row_size = 3 * w;
// if the file width (3*w) is not a multiple of 4 adds enough bytes to make it
// a multiple of 4
int padding = (4 - (row_size) % 4) % 4;
row_size += padding;
int filesize = 54 + row_size * total_h;
std::vector<char> img(row_size * h);
std::fill(img.begin(), img.end(), 0);
for (int i = 0; i < h; i++) {
for (int j = 0; j < w; j++) {
float v = ((m_grid(i + start, j) - m_min) / (m_max - m_min));
float r = v * 255; // Red channel
float g = v * 255; // Green channel
float b = v * 255; // Red channel
r = std::min(r, 255.f);
g = std::min(g, 255.f);
b = std::min(b, 255.f);
img[row_size * i + 3 * j + 2] = r;
img[row_size * i + 3 * j + 1] = g;
img[row_size * i + 3 * j + 0] = b;
}
}
std::array<char, 14> bmpfileheader = {'B', 'M', 0, 0, 0, 0, 0,
0, 0, 0, 54, 0, 0, 0};
std::array<char, 40> bmpinfoheader = {40, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 1, 0, 24, 0};
bmpfileheader[2] = filesize;
bmpfileheader[3] = filesize >> 8;
bmpfileheader[4] = filesize >> 16;
bmpfileheader[5] = filesize >> 24;
bmpinfoheader[4] = w;
bmpinfoheader[5] = w >> 8;
bmpinfoheader[6] = w >> 16;
bmpinfoheader[7] = w >> 24;
bmpinfoheader[8] = total_h;
bmpinfoheader[9] = total_h >> 8;
bmpinfoheader[10] = total_h >> 16;
bmpinfoheader[11] = total_h >> 24;
bmpinfoheader[20] = (filesize - 54);
bmpinfoheader[21] = (filesize - 54) >> 8;
bmpinfoheader[22] = (filesize - 54) >> 16;
bmpinfoheader[23] = (filesize - 54) >> 24;
MPI_File fh;
MPI_Status status;
// opening a file in write and create mode
MPI_File_open(MPI_COMM_WORLD, sfilename.str().c_str(),
MPI_MODE_WRONLY | MPI_MODE_CREATE,
MPI_INFO_NULL, &fh);
// defining the size of the file
MPI_File_set_size(fh, filesize);
// rank 0 writes the header
if (prank == 0) {
MPI_File_write_at(fh, 0, bmpfileheader.data(), 14, MPI_CHAR, &status);
MPI_File_write_at(fh, 14, bmpinfoheader.data(), 40, MPI_CHAR, &status);
}
int offset = 54 + row_size * offset_h;
// We also could write that data with a write_at, the view is just to show
// different possibilities
MPI_File_set_view(fh, offset, MPI_CHAR, MPI_CHAR, "native",
MPI_INFO_NULL);
MPI_File_write(fh, img.data(), img.size(), MPI_CHAR, &status);
MPI_File_close(&fh);
}
c4science · Help