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模拟操作系统中进程的三种基础状态与内存的分配和回收(最佳适配算法)
利用键盘模拟进程的三种操作状态，并且使用C++中的list模板模拟内存的分配和回收。
能够模拟进程的创建与撤销过程
l可对进程的状态进行全面的控制
按先进先出方式管理就绪和阻塞队列，能够按队列形式输出进程状
用PCB代表进程，用全局变量表示进程的个数。
1 #include <iostream> 2 #include <list> 3 #include <numeric> 4 #include <algorithm> 5 #include<stdlib.h> 6 using namespace std; 7 8 9 struct PCB //PCB结构体 10 { 11 char name[10]; //外部标记 12 int PID; //内部标记 13 int begin; //起始地址 14 int length; //长度 15 struct PCB* next; 16 }; 17 18 19 struct Memory 20 { 21 int start; //起始地址 22 int len; //长度 23 bool operator < (const struct Memory p) const 24 { 25 return len < p.len; 26 } 27 28 }; 29 typedef list <Memory> Memy;//用模板定义Memory的列表 30 31 int SIZE; //用来存储内存的大小 32 Memy LM; //用来存储内存分配的链表 33 Memy::iterator K; 34 Memory L; //第一块完整的内存 35 static int number = 0; 36 //number用来标记进程的数量。 37 38 //创建三个链表，分别代表，就绪，执行，阻塞 39 struct PCB* Ready = new struct PCB; 40 struct PCB* Blocked = new struct PCB; 41 struct PCB* Running = new struct PCB; 42 43 44 bool px(struct Memory m, struct Memory n) 45 { 46 return m.start < n.start; 47 } 48 49 50 void CreateProcess(struct PCB* &Ready, Memy &LM)//创建进程 51 { 52 LM.sort(); 53 struct PCB* P = new struct PCB; 54 struct PCB* X = new struct PCB;//利用X来做到插入队尾 55 56 X = Ready; 57 58 //cout << "请输入此进程的名称：" << endl; 59 cin >> P->name; 60 61 62 //cout << "请输入此进程大小：" << endl; 63 cin >> P->length; 64 65 for (K = LM.begin(); K != LM.end(); K++)//分配内存， 66 { 67 Memy::iterator x; 68 if (K->len <= 0) 69 { 70 cout << "已经没有足够的内存空间！" << endl; 71 return; 72 } 73 if (K->len < P->length) 74 { 75 x = K; 76 K++; 77 if (K == LM.end()) 78 { 79 cout << "已经没有足够的内存空间！" << endl; 80 return; 81 } 82 else 83 { 84 K = x; 85 continue; 86 } 87 } 88 else if (K->len >= P->length) 89 { 90 if (K->len - P->length <= 2) 91 { 92 P->begin = K->start; 93 P->length = K->len; 94 LM.erase(K); 95 number++; 96 break; 97 } 98 else 99 {100 P->begin = K->start;101 K->start += P->length;//修改起始地址102 K->len -= P->length;103 number++;104 break;105 }106 }107 else108 {109 continue;110 }111 }112 113 P->PID = number; //利用number来进行唯一系统内部进程标示114 while (X->next != NULL) //新建节点连接到链表尾部115 {116 X = X->next;117 }118 X->next = P;119 P->next = NULL;120 }121 122 123 void sort1(Memy &LM) //按照长度进行排序124 {125 LM.sort();126 }127 128 129 void EndProcess(struct PCB* &Running, Memy &LM) //结束进程130 {131 if (Running->next == NULL)132 {133 cout << "没有进程处于执行态！" << endl;134 system("pause");135 return;136 }137 LM.sort(px);138 Memory O;139 O.start = Running->next->begin;140 O.len = Running->next->length;141 if (LM.size() == 0) //系统剩余空间为0，直接插入。142 {143 Memory M;144 M.len = O.len;145 M.start = O.start;146 LM.push_back(M);147 }148 else149 {150 for (K = LM.begin(); K != LM.end(); K++)151 {152 if (K->start>(O.start + O.len)) //上下都被占用 直接插入前面153 {154 Memory m;155 m.len = O.len;156 m.start = O.start;157 LM.push_front(m);158 break;159 }160 else if ((O.start + O.len) == K->start) //上占下空 改下区基址，改长度161 {162 K->start = O.start;163 K->len += O.len;164 break;165 }166 else if ((K->start + K->len) == O.start) //上空==============================================167 {168 int l = K->len;169 Memy::iterator X;170 X = K;171 ++K;172 if (K != LM.end())173 {174 if (K->start == (O.start + O.len)) //上空下空175 {176 X->len = K->len + l + O.len; //长度三合一//删除++K177 LM.erase(K);178 break;179 }180 else //上空 下占 改上区长度181 {182 X->len += O.len;183 break;184 }185 }186 else //上空 下占 改上区长度187 {188 X->len += O.len;189 break;190 }191 }192 else if ((K->start + K->len)<O.start) //提前进入下一次循环 193 {194 continue;195 }196 }197 }198 199 200 while (Running->next != NULL)201 {202 struct PCB* P = Running->next;203 P->next = NULL;204 delete P;205 Running->next = NULL;206 number--;207 }208 }209 210 211 void show(struct PCB* Ready, struct PCB* Running, struct PCB* Blocked)//显示三种状态的进程情况212 {213 cout << "就绪态：";214 while (Ready->next != NULL)215 {216 cout << " name: " << Ready->next->name << " begin: " << Ready->next->begin << " length: " << Ready->next->length;217 Ready = Ready->next;218 }219 cout << endl;220 cout << "执行态：";221 if (Running->next != NULL)222 {223 cout << "name: " << Running->next->name << " begin: " << Running->next->begin << " len: " << Running->next->length;224 }225 cout << endl;226 cout << "阻塞态:";227 while (Blocked->next != NULL)228 {229 cout << "name: " << Blocked->next->name << " begin: " << Blocked->next->begin << " len: " << Blocked->next->length;230 Blocked = Blocked->next;231 }232 cout << endl;233 int sum = 0;234 for (K = LM.begin(); K != LM.end(); K++)235 {236 cout << "内存起始地址： " << K->start << "内存长度：" << K->len << endl;237 sum += K->len;238 }239 cout << "进程所占空间: " << (SIZE - sum) << endl;240 cout << "系统空闲空间: " << sum << endl;241 sum = 0;242 }243 244 245 void Run(struct PCB* &Ready, struct PCB* &Running) //执行函数，查询就绪态中的PCB246 {247 while ((Ready->next != NULL) && (Running->next == NULL))248 {249 struct PCB* Z = Ready->next;250 Running->next = Z;251 Ready->next = Ready->next->next;252 Z->next = NULL;253 }254 }255 256 257 void Block(struct PCB* &Running, struct PCB* &Blocked) //执行到阻塞的转换258 {259 struct PCB* Head = Blocked;260 while (Running->next != NULL)261 {262 while (Head->next != NULL)263 {264 Head = Head->next;265 }266 Head->next = Running->next;267 Running->next = NULL;268 }269 }270 271 272 void TimeUp(struct PCB* &Running, struct PCB* &Ready) //时间片到273 {274 struct PCB* Head = Ready;275 struct PCB* P = Running->next;276 P->next = NULL;277 while (Running->next != NULL)278 {279 while (Head->next != NULL)280 {281 Head = Head->next;282 }283 Head->next = P;284 Running->next = NULL;285 }286 }287 288 289 void Wake(struct PCB* &Blocked, struct PCB* &Ready)//唤醒进程290 {291 if (Blocked->next == NULL)292 {293 cout << "没有进程处于阻塞态！" << endl;294 system("pause");295 return;296 }297 struct PCB* P = Ready;298 while (P->next != NULL)299 {300 P = P->next;301 }302 if (Blocked->next != NULL)303 {304 P->next = Blocked->next;305 Blocked->next = Blocked->next->next;306 P->next->next = NULL;307 }308 else309 {310 cout << "没有处于阻塞状态的进程！" << endl;311 }312 313 }314 315 316 void interface()317 {318 cout << "========帮助========" << endl;319 cout << "C----------创建进程" << endl;320 cout << "T----------时间片到" << endl;321 cout << "S----------进程阻塞" << endl;322 cout << "W----------唤醒进程" << endl;323 cout << "E----------结束进程" << endl;324 cout << "H----------查看帮助" << endl;325 326 }327 328 329 void start()330 {331 cout << "请输入内存的起始地址：" << endl;332 cin >> L.start;333 cout << "请输入内存的大小：" << endl;334 cin >> L.len;335 SIZE = L.len;336 LM.push_front(L);337 }338 339 340 void process() // 中间过程341 {342 interface(); 343 system("pause");344 char choice;345 do346 {347 system("cls"); 348 cin >> choice;349 switch (choice)350 {351 case ‘C‘:LM.sort(px); CreateProcess(Ready, LM); Run(Ready, Running); show(Ready, Running, Blocked); system("pause"); break;352 case ‘T‘:TimeUp(Running, Ready); Run(Ready, Running); show(Ready, Running, Blocked); system("pause"); break;353 case ‘S‘:Block(Running, Blocked); Run(Ready, Running); show(Ready, Running, Blocked); system("pause"); break;354 case ‘W‘:Wake(Blocked, Ready); Run(Ready, Running); show(Ready, Running, Blocked); system("pause"); break;355 case ‘E‘:EndProcess(Running, LM); Run(Ready, Running); show(Ready, Running, Blocked); sort1(LM); system("pause"); break;356 case ‘H‘:interface();break;357 default:cout << "输入错误，请重新输入！" << endl; system("pause"); break;358 }359 360 } while (number != 0);361 }362 363 364 void main()365 {366 Ready->next = NULL;367 Blocked->next = NULL;368 Running->next = NULL;369 start();370 process();371 cout << "所有进程已结束" << endl;372 system("pause");373 374 }
模拟操作系统中进程的三种基础状态与内存的分配和回收(最佳适配算法)
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