實驗目的本實驗主要讓大家熟悉內(nèi)存的各種分配和回收。通過本實驗，幫助大家理解不同的存儲管理方式下，如何實現(xiàn)內(nèi)存空間的分配與回收。實驗內(nèi)容確定內(nèi)存空間分配表；采用最先適應算法完成內(nèi)存空間的分配和回收；編寫主函數(shù)對所做工作進行測試。設計思路先創(chuàng)建好空閑分區(qū)表，用戶輸入作業(yè)的所需分配的空間大小，從表頭依次查詢空閑分區(qū)表，若有適合該作業(yè)的空閑分區(qū)，則將該空閑分區(qū)分配與作業(yè)相同大小的分區(qū)給作業(yè)，若無則需等待，然后將空閑分區(qū)表按始地址從小到大順序進行排列。帶作業(yè)執(zhí)行完后，釋放該分區(qū)，再將空閑分區(qū)表按始地址從小到大順序進行排列。關鍵代碼#include<stdio.h>#defineN5 //空閑區(qū)塊數(shù)typedefstructfreearea(intstartaddress;//空閑分區(qū)始址intsize; //空閑分區(qū)長度intstate; 〃標志位，0表示空，1表示未分配freearea;freeareafreeblock[N]={{87,18,1},{115,25,1},{154,102,1},{300,30,0},{600,100,1}};//給作業(yè)分配主存空間函數(shù)intalloc(intapplysize)(inti,flag=0;〃用來標識是否有滿足作業(yè)的空閑空間，1表示有，0表示無for(i=0;i<N;i++)(if(freeblock[i].state==1&&freeblock[i].size>applysize)(freeblock[i].startaddress二freeblock[i].startaddress+applysize;freeblock[i].size二freeblock[i].size-applysize;flag=1;returnfreeblock[i].startaddress-applysize;}if(freeblock[i].state==1&&freeblock[i].size==applysize)(freeblock[i].state=0;flag=1;returnfreeblock[i].startaddress;}}if(flag==0)return-1;}voidsetfree()(intaddress,size;intflag1=0,flag2=0,flag3=0;//flag1:表示回收區(qū)是否有下鄰空閑區(qū)；flag2:表示回收區(qū)是否有上下鄰空閑區(qū)；flag3:表示回收區(qū)是否有上鄰空閑區(qū)；inti,j;printf("請輸入要釋放區(qū)域的起始地址:\n");scanf("%d",&address);printf("請輸入要釋放區(qū)域的大?。篭n");scanf("%d",&size);for(i=0;i<N;i++)(if(freeblock[i].startaddress==address+size&&freeblock[i].state==1)//回收區(qū)有下鄰空閑區(qū)(size=size+freeblock[i].size;〃向下合并空閑區(qū)flag1=1;for(j=0;j<N;j++)if(freeblock[j].startaddress+freeblock[j].size==address &&freeblock[j].state==1)(freeblock[i].state=0;freeblock[j].size=freeblock[j].size+size;//向上合并空閑區(qū)flag2=1; 〃回收區(qū)有上下鄰空閑區(qū)break;}if(flag2==0)//回收區(qū)無上鄰空閑區(qū)(freeblock[i].startaddress=address;freeblock[i].size二size;break;}}if(flag1==0) //回收區(qū)無下鄰空閑區(qū)，檢查其是否有上鄰空閑區(qū)(for(i=0;i<N;i++)if(freeblock[i].startaddress+freeblock[i].size==address &&freeblock[i].state==1)(freeblock[i].size二freeblock[i].size+size;flag3=1;break;}if(flag3==0)//回收區(qū)無上鄰空閑區(qū)for(j=0;j<N;j++)if(freeblock[j].state==0)〃將釋放區(qū)放入空表目中(freeblock[j].startaddress二address;freeblock[j].size二size;freeblock[j].state=1;break;}}}voidadjust()(inti,j;freeareatemp;//中間變量for(i=0;i<N;i++) //將空閑區(qū)按始地址順序在表中排列for(j=0;j<N;j++)if(freeblock[j].startaddress>freeblock[j+1].startaddress)(temp.startaddress=freeblock[j].startaddress;temp.size=freeblock[j].size;temp.state=freeblock[j].state;freeblock[j].startaddress=freeblock[j+1].startaddress;freeblock[j].size=freeblock[j+1].size;freeblock[j].state=freeblock[j+1].state;freeblock[j+1].startaddress=temp.startaddress;freeblock[j+1].size二temp.size;freeblock[j+1].state二temp.state;}for(i=0;i<N;i++)/*將空表目放在表后面*/for(j=0;j<N;j++)if(freeblock[j].state==0&&freeblock[j+1].state==1)(temp.startaddress二freeblock[j].startaddress;temp.size二freeblock[j].size;temp.state二freeblock[j].state;freeblock[j].startaddress二freeblock[j+1].startaddress;freeblock[j].size二freeblock[j+1].size;freeblock[j].state二freeblock[j+1].state;freeblock[j+1].startaddress二temp.startaddress;freeblock[j+1].size二temp.size;freeblock[j+1].state二temp.state;}}〃打印空閑分區(qū)表voidprint()(inti;printf("|start(始址)|size(長度)|state(標志位)|\n〃)；for(i=0;i<N;i++)(printf("| %8d | %8d | %8d\n”,freeblock[i].startaddress,freeblock[i].size,freeblock[i].state);}}main()(intapplysize,staAddress;charchoice;printf("\n是否有作業(yè)需要分配空間？(yorn:)\n");choice=getchar();while(choice=='y')(printf("\n空閑分區(qū)表為:\n");adjust();print();printf("\n請輸入需分配的空間大?。篭n");scanf(〃％d〃，&applysize);staAddress二alloc(applysize);adjust();printf("\n經(jīng)過分配后，空閑分配表為：\n");print();if(staAddress==-1)(printf("沒有合適的空閑區(qū)，請等待！")；}else(printf("\n該作業(yè)在已分配表中的始址為：％d\n”,staA