Intro to operating system

/** @file p4-start.c * * @author Your Name * @assg Programming Assignment #4 * @date March 8, 2019 */ #include <stdlib.h> #include <iostream> #include <fstream> #include <string> using namespace std; // guarantee simulations have no more than this number of page references // and we guarantee that you don't need to simulate a memory of more // than this number of physical pages const int MAX_PAGE_REFERENCES = 50; const int MAX_PHYSICAL_PAGES = 10; /** fifo page replacement simulation * Perform first-in first-out (FIFO) page replacement simulation. * * @arg framesize The number of physical frames of memory to simulate. * @arg numref The number of page references in the simulated page address * stream. There should be pagestream[0] to pagestream[numref-1] * pages in the pagestream. * @arg pagestream An array of integers. The value indicates a references * page, and the index is the time when the page was referenced. */ void fifo(int framesize, int numref, int* pagestream) { // implement fifo (first-in-first-out) page replacement here // an example of stepping through time and the pagestream to get // you going for (int time=0; time < numref; time++) { cout << "Time: " << time << endl; cout << "Page: " << pagestream[time] << endl; cout << endl; } } /** lru page replacement simulation * Perform least recently used (LRU) page replace simulation. * * @arg framesize The number of physical frames of memory to simulate. * @arg numref The number of page references in the simulated page address * stream. There should be pagestream[0] to pagestream[numref-1] * pages in the pagestream. * @arg pagestream An array of integers. The value indicates a references * page, and the index is the time when the page was referenced. */ void lru(int framesize, int numref, int* pagestream) { // implement lru (least recently used) page replacement here // an example of stepping through time and the pagestream to get // you going for (int time=0; time < numref; time++) { cout << "Time: " << time << endl; cout << "Page: " << pagestream[time] << endl; cout << endl; } } /** Load page references from file * Load the stream of simulated page references from the indicate file. * return the references in a simple array of integers. * * @param simfilename The name of the file to open and read page references * from. * @param pagestream Should be a pointer to an array of integers. The array * is filled with the page references on return. The index of each * reference indicates time when the page references occurs in * simulation. * @returns int The number of page references in the page stream. */ int loadPageStream(char* simfilename, int* pagestream) { ifstream pagestreamfile(simfilename); int pageref; int time; // If we can't open file, abort and let the user know problem if (!pagestreamfile.is_open()) { cout << "Error: could not open page simulation file: " << simfilename << endl; exit(1); } // Load simulated page references into integer array time = 0; while (!pagestreamfile.eof()) { pagestreamfile >> pageref; pagestream[time] = pageref; time++; pagestreamfile >> ws; // extract newlines from end of line } return time; } /** Main entry point of simulator * The main entry point of the page replacement simulator. Process * command line arguments and call appropriate simulation. We expect * three command line arguments: pageref.sim [fifo|lru] framesize * * @param argc The argument count * @param argv The command line argument values. We expect argv[1] to be the * name of a file in the current directory holding page file * references, argv[2] to indicate [fifo|lru] and argv[3] to be * an integer indicating size of memory in frames. */ int main(int argc, char** argv) { int framesize = 0; int pagestream[MAX_PAGE_REFERENCES]; int numref; string scheme; // If not all parameters not provided, abort and let user know of problem if (argc != 4) { cout << "Usage: " << argv[0] << " pageref.sim [lru|fifo] framesize" << endl; exit(1); } // load page stream and parse command line arguments numref = loadPageStream(argv[1], pagestream); scheme.assign(argv[2]); framesize = atoi(argv[3]); // perform simulation of indicated replacement scheme if (scheme == "lru") { lru(framesize, numref, pagestream); } else if (scheme == "fifo") { fifo(framesize, numref, pagestream); } else { cout << "Error: unknown page replacement scheme: " << scheme << endl; exit(1); } }