可变式分区的分配与回收主程序.doc

/*可变式分区的分配与回收主程序首次适应算法*/#include #define N 5struct freearea /*定义一个空闲区说明表结构,并初始化变量*/int startaddress;/*空闲区地址*/int size;/*空闲区大小*/int state;/*空闲区状态:0为空表目,1为可用空闲块*/freeblockN=20,20,1,80,50,1,150,100,1,300,30,0,600,100,1;/*定义为作业分配主存空间的函数alloc()*/int alloc(int applyarea) /*applyarea为作业申请量*/int i,tag=0;/*tag为检查是否有满足作业若需要的空闲区的标志*/for(i=0;iapplyarea)freeblocki.startaddress=freeblocki.startaddress+applyarea;freeblocki.size=freeblocki.size-applyarea;tag=1;/*有满足条件的空闲区时,tag置1*/return freeblocki.startaddress-applyarea;else if(freeblocki.state=1&freeblocki.size=applyarea)freeblocki.state=0;tag=1;/*有满足条件的空闲区时,tag置1*/return freeblocki.startaddress;/*返回为作业分配的主存地址*/if(tag=0)return -1;/*没有满足条件的空闲区,分配不成功,返回-1*/*定义主存回收函数:setfree()*/*tag1代表释放区的高地址是否邻接一个空闲区,tag2代表释放区的高低地址是否都邻接一个空闲区,tag3代表释放区的低地址是否邻接一个空闲区*/setfree()int s,l,tag1=0,tag2=0,tag3=0,i,j;printf(input free area startaddress:n);scanf(%d,&s);/*输入释放区的开始地址*/ printf(input free area size:n);scanf(%d,&l);/*输入释放区的大小*/for(i=0;iN;i+)if(freeblocki.startaddress=s+1&freeblocki.state=1)l=1+freeblocki.size;tag1=1;/*有与释放区的高地址邻接的空闲区,tag1置1*/for(j=0;jN;j+)if(freeblockj.startaddress+freeblockj.size=s&freeblockj.state=1)freeblocki.state=0;freeblockj.size=freeblockj.size+1; tag2=1;/*有与释放区上下都邻接的空闲区,tag2置1*/break;if(tag2=0)/*无与释放区高地址邻接的空闲区*/freeblocki.startaddress=s;freeblocki.size=1;break;if(tag1=0)/*无与释放区高地址邻接的空闲区,检查是否低地址有邻接空闲区*/for(i=0;iN;i+)if(freeblocki.startaddress+freeblocki.size=s&freeblocki.state=1)freeblocki.size=freeblocki.size+1;tag3=1;/*有与释放区低地址邻接的空闲区,tag3置1*/break;if(tag3=0)/*无与释放区高低地址邻接的空闲区*/for(j=0;jN;j+)if(freeblockj.state=0)/*找一个空白表,将释放区放入表中*/freeblockj.startaddress=s; freeblockj.size=1;freeblockj.state=1;break;/*定义对空闲区表中的空闲区调整的函数adjust(),使空闲区按始地址从小到大排列,空表目放在后面*/adjust()int i,j;struct freearea middata;for(i=0;iN;i+)/*将空闲区按始地址顺序在表中排列*/for(j=0;jfreeblockj+1.startaddress)middata.startaddress=freeblockj.startaddress;middata.size=freeblockj.size; middata.state=freeblockj.state; freeblockj.startaddress=freeblockj+1.startaddress;freeblockj.size=freeblockj+1.size; freeblockj.state=freeblockj+1.state; freeblockj+1.startaddress=middata.startaddress;freeblockj+1.size=middata.size; freeblockj+1.state=middata.state;for(i=0;iN;i+)/*将空表目放在表后面*/for(j=0;jN;j+)if(freeblockj.state=0&freeblockj+1.state=1)middata.startaddress=freeblockj.startaddress; middata.size=freeblockj.size; middata.state=freeblockj.state; freeblockj.startaddress=freeblockj+1.startaddress; freeblockj.size=freeblockj+1.size; freeblockj.state=freeblockj+1.state; freeblockj+1.startaddress=middata.startaddress; freeblockj+1.size=middata.size; freeblockj+1.state=middata.state;/*定义打印空闲区说明表函数:print()*/print() int i; printf( |.|n);printf( | start size state |n);printf( |.|n);for(i=0;iN;i+)printf( | %3d %3d %3d |n,freeblocki.startaddress,freeblocki.size,freeblocki.state); printf( |.|n);main()/*主函数*/int applyarea,start,j;char end;printf(n is there any job request memory?y or n:);while(end=getchar()=y)printf(at first the free memory is this:n); adjust();/*对空闲区表中的空闲区调整的函数*/ print();/*打印空闲区表的初始状态*/ printf(input request memory size:); scanf(%d,&applyarea);/*输入作业的申请量*/ start=alloc(applyarea);/*调用alloc()函数,为作业分配空间,start为返回的始地址*/ adjust(); printf(after allocation,the free memory is this:n); print();/*打印空闲区表*/ if(start=-1)/*alloc()分配不成功时,返回-1*/ printf(there is no fit memory,please waitn); else printf(jobs memory start address is: %dn,start); printf(job size is: %dn,applyarea); printf(job is running. n); printf(job is terminated.