存储管理分区分配算法
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/*9.3.2 源程序*/
/***pcb.c***/
#include "stdio.h"
#include "stdlib.h"
#include "string.h"
#define MAX 32767
typedef 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");
else
printf("Success!!ADDRESS=%5d\n",assign1->address); /*分配成功*/
print(head); /*输出*/
}
else
if(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*/
else
acceptment2(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 { 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; } else if(before->size==head->size) maxblocknum++; before=before->next; } } } assign1=assign;