实验四主存空间的分配和回收

#include <stdio.h>
#include <conio.h>
#include <string.h>

#define MAX 512  //设置总内存大小为512k

struct partition {
    char    pn[10];//分区名字
    int    begin;//起始地址
    int    size;//分区大小 
    int    end;//结束地址
    char    status;//分区状态
};
struct partition    part[MAX];
int            p = 0; //标记上次扫描结束处 

void Init()//初始化分区地址、大小以及状态
{
    int i;
    for ( i = 0; i < MAX; i++ )
        part[i].status = ‘-‘;
   
	strcpy( part[0].pn, "SYSTEM" );
    part[0].begin    = 0;
    part[0].size    = 120;
    part[0].status    = ‘u‘;


    strcpy( part[1].pn, "-----" );
    part[1].begin    = 100;
    part[1].size    = 80;
    part[1].status    = ‘f‘;
    
	strcpy( part[2].pn, "A" );
    part[2].begin    = 200;
    part[2].size    = 55;
    part[2].status    = ‘u‘;
  
	strcpy( part[3].pn, "-----" );
    part[3].begin    = 300;
    part[3].size    = 45;
    part[3].status    = ‘f‘;
   
	strcpy( part[4].pn, "B" );
    part[4].begin    = 400;
    part[4].size    = 92;
    part[4].status    = ‘f‘;
   
	
	strcpy( part[5].pn, "-----" );
    part[5].begin    = 500;
    part[5].size    = 120;
    part[5].status    = ‘f‘;
    for ( i = 0; i < MAX; i++ )
        part[i].end = part[i].begin + part[i].size;
}


void Output( int i ) //以行的形式输出结构体的数据
{
    printf( "\t%s", part[i].pn );
    printf( "\t%d", part[i].begin );
    printf( "\t%d", part[i].size );
    printf( "\t%d", part[i].end );
    printf( "\t%c", part[i].status );
}


void Show() //显示分区 
{
    int    i;
    int    n; //用n来记录分区的个数
    printf( "\n==========================================================" );
    printf( "\n已分配分区表Used:" );
    printf( "\n\tNo.\tproname\tbegin\tsize\tend\tstatus" );
 printf("\n");
    n = 1;
    for ( i = 0; i < MAX; i++ )
    {
        if ( part[i].status == ‘-‘ )
            break;
        if ( part[i].status == ‘u‘ )
        {
            printf( "\n\tNo.%d", n );
            Output( i );
            n++;// 记录已分配使用的分区个数
        }
    }
  
    printf("\n------------------------------------------------------------");
    printf( "\n空闲分区表Free:" );
    printf( "\n\tNo.\tproname\tbegin\tsize\tend\tstatus" );
  
    n = 1;
    for ( i = 0; i < MAX; i++ )
    {
        if ( part[i].status == ‘-‘ )
            break;
        if ( part[i].status == ‘f‘ )
        {
            printf( "\n\tNo.%d", n );
            Output( i );
            n++;  //记录空闲分区的个数
        }
    }
    printf( "\n" );
    printf( "\n-----------------------------------------------------------");

    printf( "\n内存使用情况，按起始址增长的排:" );
    printf( "\nprintf sorted by address:" );
    printf( "\n\tNo.\tproname\tbegin\tsize\tend\tstatus" );
   printf("\n");
    n = 1;
    for ( i = 0; i < MAX; i++ )
    {
        if ( part[i].status == ‘-‘ )
            break;
        printf( "\n\tNo.%d", n );
        Output( i );
        n++;//记录已分配分区以及空闲分区之和的总个数
    }
    getch();
}

void Fit( int a, char workName[], int workSize ) //新作业把一个分区分配成两个分区：已使用分区和空闲分区 
{
    int i;
    for ( i = MAX; i > a + 1; i-- )
    {
        //通过逆向遍历，把在a地址后的所有分区往后退一个分区，目的在于增加一个分区
        if ( part[i - 1].status == ‘-‘ )
            continue;
        part[i]=part[i-1];
    }
    strcpy( part[a + 1].pn, "-----" );
    part[a + 1].begin    = part[a].begin + workSize;
    part[a + 1].size    = part[a].size - workSize;
    part[a + 1].end        = part[a].end;
    part[a + 1].status    = ‘f‘;
    strcpy( part[a].pn, workName );
    part[a].size    = workSize;
    part[a].end    = part[a].begin + part[a].size;
    part[a].status    = ‘u‘;
}


void Allocation() // 分配 
{
    int    i;
    int    a;
    int    workSize;
    char    workName[10];
    int    pFree;
    printf( "\n请输入作业名称：" );
    scanf( "%s", &workName );
    for(i=0;i<MAX;i++)
    {
        if(!strcmp(part[i].pn,workName))//判断作业名称是否已经存在
        {
            printf("\n作业已经存在，不必再次分配！\n");
            return;
        }
    }
    printf( "请输入作业大小(k)：" );
    scanf( "%d", &workSize );
    for ( i = 0; i < MAX; i++ )//通过循环在空闲区找是否有适合区间存储作业
    {
        if ( part[i].status == ‘f‘ && part[i].size >= workSize )
        {
            pFree = i;
            break;
        }
    }
    if ( i == MAX )
    {
        printf( "\n该作业大小超出最大可分配空间" );
        getch();
        return;
    }
	printf( "\n-----------------------------------------------------------");
    printf( "\n请选择分配算法：" );
    printf( "\n1、首次适应算法(FF)" );
    printf( "\n2、循环首次适应算法(NF)" );
    printf( "\n3、最优适应算法(BF)" );
    printf( "\n4、最坏适应算法(WF)" );
    printf( "\n请输入选项：" );
    while ( 1 )
    {
        scanf( "%d", &a );
        if ( a == 1 || a == 2 || a == 3 || a == 4 )
            break;
        printf( "输入错误，请重新输入：" );
    }
    switch ( a )
    {
    case 1:
        for ( i = 0; i < MAX; i++ )//首次适应算法(按地址从低到高查找)
            if ( part[i].status == ‘f‘ && part[i].size >= workSize )
                break;
        Fit( i, workName, workSize );
        break;
    case 2:
        for ( p; p <= MAX; p++ )//循环首次适应算法
        {
            if ( p == MAX )//如果p指向地址末尾还没找到适合区间，则循环返回首地址0，继续寻找
                p = 0;      
            if ( part[p].status == ‘f‘ && part[p].size >= workSize )
                break;
        }
        Fit( p, workName, workSize );
        break;
    case 3:
        for ( i = 0; i < MAX; i++ )//最佳适应算法
            if ( part[i].status == ‘f‘ && part[i].size >= workSize )
                if ( part[pFree].size > part[i].size )
                    pFree = i;//通过遍历所有区间，每次都找到最小空闲分区进行分配
        Fit( pFree, workName, workSize );
        break;
    case 4:
        for ( i = 0; i < MAX; i++ )//最坏适应算法
            if ( part[i].status == ‘f‘ && part[i].size >= workSize )
                if ( part[pFree].size < part[i].size )
                    pFree = i;//通过遍历所有区间，每次都找到最大空闲区分配
        Fit( pFree, workName, workSize );
        break;
    default:
        break;
    }
    printf( "\n分配成功！" );
    getch();
}


void Merge() //合并连续的空闲分区 
{
    int i = 0;
    while ( i != MAX - 1 )
    {
        for ( i = 0; i < MAX - 1; i++ )
        {
            if ( part[i].status == ‘f‘ )
                if ( part[i + 1].status == ‘f‘ )
                {
                    part[i].size    = part[i].size + part[i + 1].size;
                    part[i].end    = part[i].begin + part[i].size;
                    i++;
                    for ( i; i < MAX - 1; i++ )
                    {
                        if ( part[i + 1].status == ‘-‘ )
                        {
                            part[i].status = ‘-‘;
                            break;
                        }
                       
                        part[i]=part[i+1];
                    }
                    part[MAX - 1].status = ‘-‘;
                    break;
                }
        }
    }
}


void Recovery() // 回收分区 
{
    int    i;
    int    number;
    int    n=0;
    printf( "\n请输入回收的分区号：" );
    scanf( "%d", &number );
    if ( number == 1 )
    {
        printf( "\n系统分区无法回收" );
        return;
    }
    
    for ( i = 0; i < MAX; i++ )//通过循环查找要回收的已使用分区区号
    {
        if ( part[i].status == ‘u‘ )
        {
            n++;
            if ( n == number )
            {
                strcpy( part[i].pn, "-----" );
                part[i].status = ‘f‘;
            }
        }
    }
    if ( i == MAX - 1 )
    {
        printf( "\n找不到分区" );
        return;
    }
    Merge();//合并连续的空闲分区
    printf( "\n回收成功！" );
    getch();
}


void main()
{
    int selection;
    Init();
    printf( "初始化，设内存容量%dk", MAX );
    printf( "\n系统从低地址部分开始使用，占用%dk", part[0].size );
    while ( 1 )
    {	
			printf( "\n" );
		printf( "\n------------------------" );
        printf( "\n---------请选择---------" );
	
        printf( "\n0、退出系统" );
        printf( "\n1、显示分区" );
        printf( "\n2、分配作业" );
        printf( "\n3、回收分区" );
        printf( "\n请选择：" );
        while ( 1 )
        {
            scanf( "%d", &selection );
            if ( selection == 0 ||selection == 1 || selection == 2 || selection == 3 )
                break;
            printf( "输入错误，请重新输入：" );
        }
        switch ( selection )
        {
        case 0:
            //exit(0); //退出系统
            break;
        case 1:
            Show(); //显示分区
            break;
        case 2:
            Allocation(); //分配作业
            break;
        case 3:
            Recovery();  //回收分区
            break;
        default:
            break;
        }
    }
}