Settings.cpp

/*
 * Distributed under the OSI-approved Apache License, Version 2.0.  See
 * accompanying file Copyright.txt for details.
 *
 * Settings.cpp
 *
 *  Created on: Feb 2017
 *      Author: Norbert Podhorszki
 */

#include <cstdlib>
#include <errno.h>

#include "Settings.h"

static unsigned int convertToUint(std::string varName, char *arg)
{
  char *end;
  int retval = std::strtoll(arg, &end, 10);
  if (end[0] || errno == ERANGE)
  {
    throw std::invalid_argument("Invalid value given for " + varName + ": " +
                                std::string(arg));
  }
  if (retval < 0)
  {
    throw std::invalid_argument("Negative value given for " + varName + ": " +
                                std::string(arg));
  }
  return (unsigned int)retval;
}

Settings::Settings(int argc, char *argv[], int rank, int nproc) : rank{rank}
{
  if (argc < 8)
  {
    throw std::invalid_argument("Not enough arguments");
  }
  this->nproc = (unsigned int)nproc;

  outputfile = argv[1];
  npx = convertToUint("N", argv[2]);
  npy = convertToUint("M", argv[3]);
  ndx = convertToUint("nx", argv[4]);
  ndy = convertToUint("ny", argv[5]);
  steps = convertToUint("steps", argv[6]);
  iterations = convertToUint("iterations", argv[7]);

  if (npx * npy != this->nproc)
  {
    throw std::invalid_argument("N*M must equal the number of processes");
  }

  // calculate global array size and the local offsets in that global space
  gndx = npx * ndx;
  gndy = npy * ndy;
  posx = rank % npx;
  posy = rank / npx;
  offsx = posx * ndx;
  offsy = posy * ndy;

  // determine neighbors
  if (posx == 0)
    rank_left = -1;
  else
    rank_left = rank - 1;

  if (posx == npx - 1)
    rank_right = -1;
  else
    rank_right = rank + 1;

  if (posy == 0)
    rank_up = -1;
  else
    rank_up = rank - npx;

  if (posy == npy - 1)
    rank_down = -1;
  else
    rank_down = rank + npx;
}

Settings::~Settings() {}