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mem.js

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+
+
+// Queue class to help with the FIFO algorithm and adapt it to the LRU algorithm
+class Queue {
+    constructor() {
+      this.items = [];
+    }
+
+    enqueue(item) {
+      this.items.push(item);
+    }
+
+    first() {
+      if (this.isEmpty()) {
+        return "Queue is empty";
+      }
+      return this.items.shift();
+    }
+
+    front() {
+      if (this.isEmpty()) {
+        return "Queue is empty";
+      }
+      return this.items[0];
+    }
+
+    isEmpty() {
+      return this.items.length === 0;
+    }
+
+    size() {
+      return this.items.length;
+    }
+
+    // used in LRU algorithm
+    remove(item) {
+        let index = this.items.indexOf(item);
+        if(index > -1) {
+            this.items.splice(index, 1);
+        }
+    }
+  }
+
+
+
+// create a class called Memory
+
+
+class Memory {
+    constructor(algorithm) {
+        this.memsize = 50;
+        this.memory = new Array(50); 
+        this.algorithm = algorithm; // consider this to be a string ("FIFO" or "LRU")
+        this.free = this.memsize; // free space in memory
+        this.active = new Queue(); // active processes in memory
+        this.LRU = new Queue(); // least recently used processes in memory
+    }
+
+
+
+
+    // operations with memory
+    allocate(process) {
+      // check if the process is already in memory
+      for(let i = 0; i < this.memsize; i++) {
+        if(this.memory[i] == process) {
+            if(this.algorithm == "LRU") { // updating the LRU queue
+                this.LRU.remove(process);
+                this.LRU.enqueue(process);
+            }
+            return;
+        }
+      }
+
+        // check if there is enough space in the memory to allocate the process
+
+        while(process.size() > this.free) {
+          // if there is not enough space, apply the algorithm to free up space and allocate the memory
+            if(this.algorithm == "FIFO") {
+                let change = this.active.first(); // get the first process in the queue( First in)
+                for(let i = 0; i < this.memsize; i++) {
+                    if(this.memory[i] == change) { // find the space in memory that the process is occupying
+                        this.memory[i] = undefined; // free up the space
+                    }
+                }
+                this.free += process.size(); // update the free space
+
+            }else{
+                let change = this.LRU.first(); // get the least recently used process
+                for(let i = 0; i < this.memsize; i++) {
+                    if(this.memory[i] == change) { // find the space in memory that the process is occupying
+                        this.memory[i] = undefined; // free up the space
+                    }
+                }
+                this.free += process.size(); // update the free space
+            }
+        }
+
+
+        // if there is enough space, allocate the memory and return the updated memory state
+        let aux = 0;
+
+        for(let i = 0; i < this.memsize; i++) {
+            if(process.size = aux){
+                break;
+            }
+            if(this.memory[i] == undefined) {
+                this.memory[i] = process;
+                this.free -= size;
+                aux++;
+            }
+        }
+        this.LRU.enqueue(process); // add the process to the queue (LAST USED)
+        this.active.enqueue(process); // add the process to the queue
+        return;
+
+    }
+
+    getMemoryState() {
+        return this.memory;
+    }
+
+}
+