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

struct partition {
char pn[10];
int begin;
int size;
int end;
char status;
};
struct partition part[MAX];
int p = 0; /*上次扫描结束处 */

void Init()
{
int i;
for ( i = 0; i < MAX; i++ )
part[i].status = '-';

strcpy( part[0].pn, "SYSTEM" );
part[0].begin = 0;
part[0].size = 100;
part[0].status = 'u';

strcpy( part[1].pn, "-----" );
part[1].begin = 100;
part[1].size = 412;
part[1].status = 'f';

for ( i = 0; i < MAX; i++ )
part[i].end = part[i].begin + part[i].size;
}

void Output( int i ) /* 输出行 */
{
printf( " %s", part[i].pn );
printf( " %d", part[i].begin );
printf( " %d", part[i].size );
printf( " %d", part[i].end );
printf( " %c", part[i].status );
}

void ShowData() /* 显示分区 */
{
int i;
int n;
printf( " ================================================================" );
printf( " 空闲分区表Free:" );
printf( " No. proname begin size end status" );
printf( " ------------------------------------------------" );
n = 1;
for ( i = 0; i < MAX; i++ )
{
if ( part[i].status == '-' )
break;
if ( part[i].status == 'f' )
{
printf( " No.%d", n );
Output( i );
n++;
}
}
printf( " " );
printf( " ================================================================" );
printf( " 已分配分区表Used:" );
printf( " No. proname begin size end status" );
printf( " ------------------------------------------------" );
n = 1;
for ( i = 0; i < MAX; i++ )
{
if ( part[i].status == '-' )
break;
if ( part[i].status == 'u' )
{
printf( " No.%d", n );
Output( i );
n++;
}
}
printf( " " );
printf( " " );
printf( " ================================================================" );
printf( " 内存使用情况，按起始址增长的排:" );
printf( " printf sorted by address:" );
printf( " No. proname begin size end status" );
printf( " ------------------------------------------------" );
n = 1;
for ( i = 0; i < MAX; i++ )
{
if ( part[i].status == '-' )
break;
printf( " No.%d", n );
Output( i );
n++;
}
getch();
}

void Fit( int a, char workName[], int workSize ) /* 分配成'u'+'f' */
{
int i;
for ( i = MAX; i > a + 1; i-- )
{
if ( part[i - 1].status == '-' )
continue;
strcpy( part[i].pn, part[i - 1].pn );
part[i].begin = part[i - 1].begin;
part[i].size = part[i - 1].size;
part[i].end = part[i - 1].end;
part[i].status = part[i - 1].status;
}
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( " 请输入作业名称：" );
while(1)
{
scanf( "%s", &workName );
for(i=0;i<MAX;i++)
{
if(part[i].status=='u' && strcmp(workName,part[i].pn)==0)
{
printf("该作业已存在，请重新输入作业名:");
break;
}
}
if(i==MAX)
break;
}
printf( "请输入作业大小(k)：" );
while(1)
{
scanf( "%d", &workSize );
for ( i = 0; i < MAX; i++ )
{
if ( part[i].status == 'f' && part[i].size >= workSize )
{
pFree = i;
break;
}
}
if ( i == MAX )
{
printf( " 该作业大小超出最大可分配空间，请重新输入:" );
}
else break;
}
printf( " 请选择分配算法：" );
printf( " 1、最先适应(first fit)" );
printf( " 2、下次适应(next fit)" );
printf( " 3、最优适应(best fit)" );
printf( " 4、最坏适应(worst fit)" );
printf( " 请输入选项：" );
while ( 1 )
{
scanf( "%d", &a );
if ( a == 1 || a == 2 || a == 3 || a == 4 )
break;
else
printf( "输入错误，请重新输入：" );
}
switch ( a )
{
case 1:
for ( i = 0; i < MAX; i++ )
if ( part[i].status == 'f' && part[i].size >= workSize )
break;
Fit( i, workName, workSize );
break;
case 2:
for ( p; p < MAX; p++ )
{
if ( p == MAX )
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++ )
if ( part[i].status == 'f' && part[i].size >= workSize )
if ( part[pFree].size > part[i].size )
pFree = i;
Fit( pFree, workName, workSize );
break;
case 4:
for ( i = 0; i < MAX; i++ )
if ( part[i].status == 'f' && part[i].size >= workSize )
if ( part[pFree].size < part[i].size )
pFree = i;
Fit( pFree, workName, workSize );
break;
default:
break;
}
printf( " 分配成功！" );
getch();
}

void Merge() /* 合并连续的'f' */
{
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;
}
strcpy( part[i].pn, part[i + 1].pn );
part[i].begin = part[i + 1].begin;
part[i].size = part[i + 1].size;
part[i].end = part[i + 1].end;
part[i].status = part[i + 1].status;
}
part[MAX - 1].status = '-';
break;
}
}
}
}

void Recovery() /* 回收分区 */
{
int i;
char workName[10];
printf( " 请输入回收的分区名称：" );
scanf( "%s", &workName );
if ( strcmp( workName, "SYSTEM" ) == 0 )
{
printf( " 该系统分区无法回收" );
return;
}

for ( i = 0; i < MAX; i++ )
{
if ( strcmp( workName, part[i].pn ) == 0 )
{
strcpy( part[i].pn, "-----" );
part[i].status = 'f';
Merge();
printf( " 回收成功！" );
getch();
return;

}
}
if ( i == MAX )
{
printf( " 找不到该分区" );
return;
}
}

void main()
{
int a;
Init();
printf( " 初始化，设内存容量%dk", MAX );
printf( " 系统从低地址部分开始使用，占用%dk", part[0].size );
printf( " " );
while ( 1 )
{
printf( " " );
printf( " 1、显示分区" );
printf( " 2、分配作业" );
printf( " 3、回收分区" );
printf( " 请输入选项：" );
while ( 1 )
{
scanf( "%d", &a );
if ( a == 1 || a == 2 || a == 3 )
break;
printf( "输入错误，请重新输入：" );
}
switch ( a )
{
case 1:
ShowData();
break;
case 2:
Allocation();
break;
case 3:
Recovery();
break;
default:
break;
}
}
}