package Others;⏎
⏎
import java.util.ArrayList;⏎
⏎
/**⏎
 * @author Dekas Dimitrios⏎
 */⏎
public class FirstFit {⏎
    private static final int NO_ALLOCATION = -255; // if a process has been allocated in position -255,⏎
                                                   // it means that it has not been actually allocated.⏎
⏎
    /**⏎
     * Method to find the index of the memory block that is going to fit the given process based on the first fit algorithm.⏎
     *⏎
     * @param blocks: the array with the available memory blocks.⏎
     * @param process: the size of the process.⏎
     * @return the index of the block that fits, or -255 if no such block exists.⏎
     */⏎
    private static int findFirstFit(int[] blockSizes, int processSize) {⏎
        for(int i=0 ; i < blockSizes.length ; i++) {⏎
            if(blockSizes[i] >= processSize) {⏎
                return i;⏎
            }⏎
        }⏎
        // If there is not a block that can fit the process, return -255 as the result⏎
        return NO_ALLOCATION;⏎
    }⏎
⏎
    /**⏎
     * Method to allocate memory to blocks according to the first fit⏎
     * algorithm. It should return an ArrayList of Integers, where the⏎
     * index is the process ID (zero-indexed) and the value is the block⏎
     * number (also zero-indexed).⏎
     *⏎
     * @param sizeOfBlocks: an int array that contains the sizes of the memory blocks available.⏎
     * @param sizeOfProcesses: an int array that contains the sizes of the processes we need memory blocks for.⏎
     * @return the ArrayList filled with Integers repressenting the memory allocation that took place.⏎
     */⏎
    static ArrayList<Integer> firstFit(int[] sizeOfBlocks, int[] sizeOfProcesses) {⏎
        // The array list responsible for saving the memory allocations done by the first-fit algorithm⏎
        ArrayList<Integer> memAlloc = new ArrayList<>();⏎
        // Do this for every process⏎
        for(int processSize : sizeOfProcesses) {⏎
            int chosenBlockIdx = findFirstFit(sizeOfBlocks, processSize); // Find the index of the memory block going to be used⏎
            memAlloc.add(chosenBlockIdx); // Store the chosen block index in the memAlloc array list⏎
            if(chosenBlockIdx != NO_ALLOCATION) { // Only if a block was chosen to store the process in it,⏎
                sizeOfBlocks[chosenBlockIdx] -= processSize; // resize the block based on the process size⏎
            }⏎
        }⏎
        return memAlloc;⏎
    }⏎
⏎
    /**⏎
     * Method to print the memory allocated.⏎
     *⏎
     * @param memAllocation: an ArrayList of Integer representing the memory allocation done by the firstFit method.⏎
     */⏎
    public static void printMemoryAllocation(ArrayList<Integer> memAllocation) {⏎
        System.out.println("Process No.\tBlock No.");⏎
        System.out.println("===========\t=========");⏎
        for (int i = 0; i < memAllocation.size(); i++) {⏎
            System.out.print(" " + i + "\t\t");⏎
            if (memAllocation.get(i) != NO_ALLOCATION)⏎
                System.out.print(memAllocation.get(i));⏎
            else⏎
                System.out.print("Not Allocated");⏎
            System.out.println();⏎
        }⏎
    }⏎
⏎