存储管理分区分配算法

/*9.3.2 源程序*//***pcb.c***/#include "stdio.h"#include "stdlib.h"#include "string.h"#define MAX 32767typedef struct node /*设置分区描述器*/{int address,size;struct node *next;}RECT;/*函数原型*/RECT *assignment(RECT *head,int application);void acceptment1(RECT *head,RECT *back1);void acceptment2(RECT *head,RECT *back1) ;int backcheck(RECT *head,RECT *back1);void print(RECT *head);/*变量声明*/RECT *head,*back,*assign1,*p;int application1,maxblocknum;char way;/*主函数*/main(){char choose[10];int check;head=malloc(sizeof(RECT)); /*建立可利用区表的初始状态*/p=malloc(sizeof(RECT));head->size=MAX;head->address=0;head->next=p;maxblocknum=1;p->size=MAX;p->address=0;p->next=NULL;print(head); /*输出可利用表初始状态*/printf("Enter the way(best or first(b/f)\n");/*选择适应策略*/ scanf("%c",&way);do{printf("Enter the assign or accept(as/ac)\n");scanf("%s",choose); /*选择分配或回收*/if(strcmp(choose,"as")==0) /*as为分配*/{printf("Input application:\n");scanf("%d",&application1);/*输入申请空间大小*/assign1=assignment(head,application1);/*调用分配函数*/if(assign1->address==-1)/*分配不成功*/printf("Too large application!,assign fails!!\n\n");elseprintf("Success!!ADDRESS=%5d\n",assign1->address); /*分配成功*/print(head); /*输出*/}elseif(strcmp(choose,"ac")==0) /*回收*/{back=malloc(sizeof(RECT));printf("Input Adress and Size!!\n");scanf("%d%d",&back->address,&back->size);/*输入回收地址和大小*/check=backcheck(head,back); /*检查*/if(check==1){if(tolower(way)=='f')/*首先适应算法*/acceptment1(head,back); /*首先适应*/elseacceptment2(head,back);/*最佳适应*/print(head);}}}while(!strcmp(choose,"as")||!strcmp(choose,"ac"));}/*分配函数*/RECT *assignment(RECT *head,int application){RECT *after,*before,*assign;assign=malloc(sizeof(RECT)); /*分配申请空间*/assign->size=application;assign->next=NULL;if(application>head->size||application<=0)assign->address=-1; /*申请无效*/else{before=head;after=head->next;while(after->size<application)/*查找适应的结点*/{before=before->next;after=after->next;}if(after->size==application) /*结点大小等于申请大小则完全分配*/ {if(after->size==head->size)maxblocknum--;before->next=after->next;assign->address=after->address;free(after);}else{if(after->size==head->size) maxblocknum--;after->size=after->size-application; /*大于申请空间则截取相应大小分配*/assign->address=after->address+after->size;if(tolower(way)=='b')/*如果是最佳适应，将截取后剩余结点重新回收到合适位置*/{before->next=after->next;back=after;acceptment2(head,back);}}if(maxblocknum==0) /*修改最大数和头结点值*/{before=head;head->size=0;maxblocknum=1;while(before!=NULL){if(before->size>head->size){head->size=before->size;maxblocknum=1;}elseif(before->size==head->size)maxblocknum++;before=before->next;}}}assign1=assign;return assign1; /*返回分配给用户的地址*/}void acceptment1(RECT *head,RECT *back1)/*首先适应*/{RECT *before,*after;int insert;before=head;after=head->next;insert=0;while(!insert) /*将回收区插入空闲区表*/{if((after==NULL)||((back1->address<=after->address)&&(back1->address>=before->address))){before->next=back1;back1->next=after;insert=1;}else{before=before->next;after=after->next;}}if(back1->address==before->address+before->size)/*与上一块合并*/ {before->size=before->size+back1->size;before->next=back1->next;free(back1);back1=before;}if(after!=NULL&&(after->address==back1->address+back1->size)){ /*与下一块合并*/back1->size=back1->size+after->size;back1->next=after->next;free(after);}if(head->size<back1->size) /*修改最大块值和最大块个数*/{head->size=back1->size;maxblocknum=1;}elseif(head->size==back1->size)maxblocknum++;}/*最佳适应，back1为回收结点的地址*/void acceptment2(RECT *head,RECT *back1){RECT *before,*after;int insert ;insert=0;before=head;after=head->next;if(head->next==NULL) /*如果可利用区表为空*/{head->size=back1->size;head->next=back1;maxblocknum++;back1->next=NULL;}else{while(after!=NULL) /*与上一块合并*/if(back1->address==after->size+after->address){before->next=after->next;back->size=after->size+back1->size;free(after);after=NULL;}else{after=after->next;before=before->next;}before=head;after=head->next;while(after!=NULL)if(after->address==back1->size+back1->address) /*与下一块合并*/ {back1->size=back1->size+after->size;before->next=after->next;free(after);after=NULL;}elsebefore=before->next;after=after->next;}before=head;/*将回收结点插入到合适的位置*/after=head->next;do{if(after==NULL||(after->size>back1->size)){before->next=back1;back1->next=after;insert=1;}else{before=before->next;after=after->next;}}while(!insert);if(head->size<back1->size) /*修改最大块值和最大块数*/{head->size=back1->size;maxblocknum++;}elseif(head->size==back1->size)maxblocknum++;}}void print(RECT *head) /*输出链表*/{RECT *before,*after;int index,k;before=head->next;index=1;if(head->next==NULL)printf("NO part for assignment!!\n");else{printf("*****index*******address********end*********size*****\n"); while(before!=NULL){printf("----------------------------------------------------\n");printf(" %-13d%-13d%-13d%-13d\n",index,before->address,before->ad dress+before->size-1,before->size);printf("----------------------------------------------------\n");index++;before=before->next;}}}/*检查回收块的合法性，back1为要回收的结点地址*/int backcheck(RECT *head,RECT *back1){RECT *before,*after;int check=1;if(back1->address<0||back1->size<0)check=0;/*地址和大小不能为负*/before=head->next;while((before!=NULL)&&check)/*地址不能和空闲区表中结点出现重叠*/ if(((back1->address<before->address)&&(back1->address+back1->size>before->address))||((back1->address>=before->address)&&(back1->address<before->address+before->size)))check=0;elsebefore=before->next;if(check==0)printf("Error input!!\n");return check; /*返回检查结果*/}。