OS（A）之储管理动态分区分配及回收算法

  1 #include<stdio.h>
  2 #include<stdlib.h>
  3 #include<string.h>
  4 #define MAX_SIZE 32767
  5 
  6 typedef struct node  //定义分区描述器的结构
  7 {
  8 int id;      //编号
  9 
 10 int adr;      //分区首地址
 11 
 12 int size;        //分区大小
 13 
 14 struct node *next;//指向下一个分区的指针
 15 }Node;
 16 Node *head1,*head2,*back1,*back2,*assign;/*head--空闲区队列首指针
 17 
 18         back--指向释放区Node结构的指针
 19 
 20         assign-指向申请的内存分区Node结构的指针*/
 21 
 22 int request; //用户申请存储区的大小（由用户输入）
 23 int check(int add,int siz,char c)//用于检查指定的释放块（由用户键入）的合法性
 24 {
 25 Node *p,*head;
 26 int check=1;
 27 if(add<0||siz<0)
 28 check=0;/*地址和大小不能为负*/
 29 if(c==‘f‘||c==‘F‘)
 30 head=head1;
 31 else
 32 head=head2;
 33 p=head->next;
 34 while((p!=NULL)&&check)/*地址不能和空闲区表中结点出现重叠*/
 35       if(((add<p->adr)&&(add+siz>p->adr))||((add>=p->adr)&&(add<p->adr+p->size)))
 36          check=0;
 37       else
 38          p=p->next;
 39 if(check==0)
 40       printf("\t输入释放区地址或大小有错误！！！\n");
 41      return check;  /*返回检查结果*/
 42 }
 43 void init()//初始化，生成两个带头节点的空闲队列指针，
 44 {   //head1指向first-fit的空闲队列头，head2指向best-fit的空闲队列头
 45 Node *p;
 46 head1=(Node*)malloc(sizeof(Node));
 47 head2=(Node*)malloc(sizeof(Node));
 48 p=(Node*)malloc(sizeof(Node));
 49 head1->next=p;
 50 head2->next=p;
 51 p->size=MAX_SIZE;
 52 p->adr=0;
 53 p->next=NULL;
 54 p->id=0;
 55 }
 56 Node*  assignment1(int num,int req)//实现首次适应算法的分配
 57 
 58 {
 59 Node *before,*after,*ass;
 60 ass=(Node*)malloc(sizeof(Node));
 61 before=head1;
 62 after=head1->next;
 63 ass->id=num;
 64 ass->size=req;
 65 
 66 while(after->size<req)
 67 {
 68 before=before->next;
 69 after=after->next;
 70 }
 71 
 72 if(after==NULL)
 73 {
 74 ass->adr=-1;//分配失败
 75 }
 76 else
 77 {
 78 if(after->size==req)
 79 {//空闲分区恰好等于所申请的内存大小
 80 before->next=after->next;
 81 ass->adr=after->adr;
 82 }
 83 
 84 else
 85 {//空闲分区大于所申请的内存大小
 86 after->size-=req;
 87 ass->adr=after->adr;
 88 after->adr+=req;
 89 
 90 
 91 }
 92 
 93 }
 94 
 95 return ass; 
 96 
 97 }
 98 
 99 
100 void acceptment1(int address,int siz,int rd)//实现首次适应算法的回收
101 {
102 Node *before,*after;
103 int insert=0;
104 back1=(Node*)malloc(sizeof(Node));
105 before=head1;
106 after=head1->next;
107 back1->adr=address;
108 back1->size=siz;
109 back1->id=rd;
110 back1->next=NULL;
111 while(!insert&&after)
112 {//将要被回收的分区插入空闲区（按首址大小从小到大插入）
113 if((after==NULL)||((back1->adr<=after->adr)&&(back1->adr>=before->adr)))
114 {
115 before->next=back1;
116 back1->next=after;
117 insert=1;
118 }
119 else
120 {
121 before=before->next;
122 after=after->next;
123 }
124 
125  
126 
127 }
128 
129 if(insert)
130 {
131 if(back1->adr==before->adr+before->size)
132 {//和前边分区合并
133 before->size+=back1->size;
134 before->next=back1->next;
135 free(back1);
136 
137 
138 }
139 
140 else if(after&&back1->adr+back1->size==after->adr)
141 {//和后边分区合并
142 back1->size+=after->size;
143 back1->next=after->next;
144 back1->id=after->id;
145 free(after);
146 after=back1;
147 }
148 printf("\t首先分配算法回收内存成功！\n");
149 }
150 
151 else
152 printf("\t首先分配算法回收内存失败！\n");
153  
154 
155 }
156 
157 
158 
159 Node*  assignment2(int num,int req)//实现最佳适应算法的分配
160 {
161 Node *before,*after,*ass,*q;
162 ass=(Node*)malloc(sizeof(Node));
163 q=(Node*)malloc(sizeof(Node));
164 before=head2;
165 after=head2->next;
166 ass->id=num;
167 ass->size=req;
168 while(after->size<req)
169 {
170 before=before->next;
171 after=after->next;
172 }
173 
174 if(after==NULL)
175 {
176 ass->adr=-1;//分配失败
177 }
178 
179 else
180 {
181 if(after->size==req)
182 {//空闲分区恰好等于所申请的内存大小
183 before->next=after->next;
184 ass->adr=after->adr; 
185 
186 }
187 
188 else
189 {//空闲分区大于所申请的内存大小
190 q=after;
191 before->next=after->next;
192 ass->adr=q->adr;
193 q->size-=req;
194 q->adr+=req;
195 before=head2;
196 after=head2->next;
197 
198 if(after==NULL)
199 
200 {
201 before->next=q;
202 q->next=NULL;
203 }
204 
205 else
206 
207 {
208 while((after->size)<(q->size))
209 {
210 before=before->next;
211 after=after->next;
212 }
213 
214  
215 
216 before->next=q;
217 q->next=after;
218 
219 }
220 
221 }
222 
223  
224 
225 }
226 
227  
228 
229 return (ass);
230 
231  
232 
233 }
234 
235  
236 
237 void acceptment2(int address,int siz,int rd)//实现最佳适应算法的回收
238 {
239 Node *before,*after;
240 int insert=0;//是否被回收的标志
241 back2=(Node*)malloc(sizeof(Node));
242 before=head2;
243 after=head2->next;
244 back2->adr=address;
245 back2->size=siz;
246 back2->id=rd;
247 back2->next=NULL;
248 
249 if(head2->next==NULL)
250 {//空闲队列为空
251 head2->next=back2;
252 head2->size=back2->size;
253 }
254 
255 else
256 {//空闲队列不为空
257 while(after)
258 {
259 if(back2->adr==after->adr+after->size)
260 {//和前边空闲分区合并
261 before->next=after->next;
262 after->size+=back2->size;
263 back2=after;
264  
265 
266 }
267 
268 else
269 {
270 before=before->next;
271 after=after->next;
272 
273 }
274 
275 }
276 
277 
278 before=head2;
279 after=head2->next;
280 while(after)
281 
282 {
283 
284 if(after->adr==back2->adr+back2->size)
285 {//和后边空闲区合并
286 before->next=after->next;
287 back2->size+=after->size;
288 
289 }
290 
291 else
292 {
293 before=before->next;
294 after=after->next;
295 }
296 
297 }
298 
299 
300 before=head2;
301 after=head2->next;
302 while(!insert)
303 {//将被回收的块插入到恰当的位置（按分区大小从小到大）
304 if(after==NULL||((after->size>back2->size)&&(before->size<back2->size)))
305          {
306             before->next=back2;
307             back2->next=after;
308             insert=1;
309 break;
310          }
311          else
312          {
313             before=before->next;
314             after=after->next;
315          }
316 
317 }
318 
319  
320 
321 }
322 
323 if(insert)
324 printf("\t最佳适应算法回收内存成功！\n");
325 else
326 printf("\t最佳适应算法回收内存失败！！\n");
327  
328 
329 }
330 
331  
332 
333  
334 
335 void print(char choice)//输出空闲区队列信息
336 {
337 Node *p;
338 if(choice==‘f‘||choice==‘F‘)
339 p=head1->next;
340 else
341 p=head2->next;
342 if(p)
343 {
344 printf("\n空闲区队列的情况为：\n");
345 printf("\t编号\t首址\t终址\t大小\n");
346 
347 while(p)
348 {
349 printf("\t%d\t%d\t%d\t%d\n",p->id,p->adr,p->adr+p->size-1,p->size);
350 p=p->next;
351 
352 }
353 
354 }
355 
356 
357 }
358 
359  
360 
361 
362 void menu()//菜单及主要过程
363 {
364 char chose;
365 int ch,num,r,add,rd;
366  while(1)
367 {
368 
369 system("cls");
370 printf("选择最先适应算法请输入F，选择最佳适应算法请输入B，退出程序请输入E\n\n");
371 printf("请输入你的选择:");
372 scanf("%c",&chose);
373 if(chose==‘e‘||chose==‘E‘)
374 exit(0);
375 
376 else
377 {
378 system("cls");
379 while(1)
380 {
381 if(chose==‘f‘||chose==‘F‘)
382 printf("最先适应算法(First-Fit)模拟:\n");
383 if(chose==‘b‘||chose==‘B‘)
384 printf("最佳适应算法(Best-Fit)模拟:\n");
385 printf("1.分配内存,2.回收内存,3.查看内存,4.返回\n\n");
386 printf("请输入你的选择:");
387 scanf("%d",&ch);
388 fflush(stdin);
389 switch(ch)
390 
391 {
392 case 1:
393 printf("输入申请的分区大小：");scanf("%d",&r);
394 if(chose==‘f‘||chose==‘F‘)
395 assign=assignment1(num,r);
396 else
397 assign=assignment2(num,r);
398 if(assign->adr==-1)
399 {
400 printf("分配内存失败！\n");
401 }
402 
403 else 
404 printf("分配成功！分配的内存的首址为:%d\n",assign->adr);
405 
406 
407 break;
408 case 2:
409 printf("输入释放的内存的首址：");scanf("%d",&add);
410 printf("输入释放的内存的大小：");scanf("%d",&r);
411 printf("输入释放的内存的编号：");scanf("%d",&rd);
412 
413 if(check(add,r,chose))
414 {
415 if(chose==‘f‘||chose==‘F‘)
416 acceptment1(add,r,rd);
417 
418 else
419 acceptment2(add,r,rd);
420 }
421 
422 break;
423 case 3:
424 print(chose);
425 
426 break;
427 
428 case 4:
429 menu();
430 break;
431 
432 }
433 
434 }
435 
436 
437 }
438 
439 }
440 
441 
442 }
443 
444  
445 
446  void main()//主函数
447  {
448 init();
449 menu();
450  
451  }