load.cpp

//
// Author:  Osayamen Aimuyo
// Created: 1/29/2023.
//

#include <cstdio>
#include <cstring>
#include <string>
#include <tuple>
#include <deque>
#include <cmath>

#include "memory/loader/load.h"
#include "utility/utility.h"
#include "memory/memory.h"
#include "computer/computer.h"

std::deque<int> free_pages;
int disk_index;

bool atEndOfPage(int index){
    return index % pageSize == 0;
}

int pages_needed(int instructions, int data){
    return ceil(((instructions * instruction_width) + data) / (pageSize * 1.0));
}

void load_init(){
    for(int i = 0; i < memorySize; ++i)
        free_pages.push_back(i);
}

MemoryMetadata load_prog(char *fname){
    FILE *programFile = fopen(fname, "r");
    MemoryMetadata m = MemoryMetadata();
    if (programFile == nullptr || feof(programFile)) {
        perror("Invalid User Program");
    }
    else{
        bool isEOF;
        std::string line;

        std::tie(std::ignore, line) = get_line(programFile); // obtains program metadata.
        std::vector<int> v = separate_spaced_str(const_cast<char *>(line.c_str()));

        m.instruction_num = v.at(0);
        m.data_num = v.at(1);

        if(free_pages.size() < pages_needed(m.instruction_num, m.data_num)) {
            //TODO: Maybe retry after running processes finish instead of returning?
            m.isOutOfMemory = true;
            return m;
        }

        std::tie(isEOF, line) = get_line(programFile);
        disk_index = get_physical_address(free_pages.front(), 0);

        while(!isEOF){
            char *word = strtok(const_cast<char*>(line.c_str()), " ");
            while(word != nullptr && strcmp(word, "\n") != 0){
                if(atEndOfPage(disk_index)){
                    disk_index = get_physical_address(free_pages.front(), 0);
                    m.page_table.push_back(free_pages.front());
                    free_pages.pop_front();
                }
                Mem.at(disk_index++) = std::stoi(word); // load instruction into memory.
                word = strtok(nullptr, " ");
            }

            std::tie(isEOF, line) = get_line(programFile);
        }
        load_finish(programFile);
    }
    return m;
}

void load_finish(std::FILE *f){
    fclose(f);
}

void reclaim_memory(const std::vector<int>& page_table){
    for(auto i : page_table){
        free_pages.push_back(i);
    }
}