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#define n 10
#define m 10
#define minisize 100
struct
{
float address;
float length;
int flag;
}used_table[n];
struct
{
float address;
float length;
int flag;
}free_table[m];
allocate(J,xk)
char J;
float xk;
{
int i,k;
float ad;
k=-1;
for (i=0;i <m;i++)
if (free_table[i].length>=xk&&free_table[i].flag==1)
if (k==-1||free_table[i].length <free_table[k].length)
k=i;
if (k==-1)
{
printf("无可用空闲区\n");
return;
}
if (free_table[k].length-xk <=minisize)
{
free_table[k].flag=0;
ad=free_table[k].address;
xk=free_table[k].length;
}
else
{
free_table[k].length=free_table[k].length-xk;
ad=free_table[k].address+free_table[k].length;
}
i=0;
while (used_table[i].flag!=0&&i <n)
i++;
if (i>=n)
{
printf("无表目填写已分分区,错误\n");
if (free_table[k].flag==0)
free_table[k].flag=1;
else
free_table[k].length=free_table[k].length+xk;
return;
}
else
{
used_table[i].address=ad;
used_table[i].length=xk;
used_table[i].flag=J;
}
return;
}
reclaim(J)
char J;
{
int i,k,j,s,t;
float S,L;
s=0;
while ((used_table[s].flag!=J||used_table[s].flag==0)&&s <n)
s++;
if (s>=n)
{
printf("找不到改作业\n");
return;
}
used_table[s].flag=0;
S=used_table[s].address;
L=used_table[s].length;
j=-1;k=-1;i=0;
while (i <m&&(j==-1||k==-1))
{
if (free_table[i].flag==0)
{
if (free_table[i].address+free_table[i].length==S)k=i;
if (free_table[i].address==S+L)j=i;
}
i++;
}
if (k!=-1)
if (j!=-1)
{
free_table[i].length=free_table[j].length+free_table[k].length+L;
free_table[j].flag=0;
}
else
free_table[k].length=free_table[k].length+L;
else
if (j!=-1)
{
free_table[j].address=S;
free_table[j].length=free_table[j].length+L;
}
else
{
t=0;
while (free_table[t].flag==1&&t <m)
t++;
if (t>=m)
{
printf("内存空闲表没有空闲。回收空间失败\n");
used_table[s].flag=J;
return;
}
free_table[t].address=S;
free_table[t].length=L;
free_table[t].flag=1;
}
return 0;
}
int main()
{
int i,a;
float xk;
char J;
free_table[0].address=10240;
free_table[0].length=102400;
free_table[0].flag=1;
for (i=0;i <m;i++)
free_table[i].flag=1;
for (i=0;i <n;i++)
used_table[i].flag=0;
while (1)
{
printf("选择功能项(0-退出,1-分配内存,2-回收内存,3-显示内存)\n");
printf("选择功能(0~3):");
scanf("%d",&a);
switch (a)
{
case 0:exit(0);
case 1:
printf("输入作业名J和作业所需长度xk: ");
scanf("%*c%c%f",&J,&xk);
allocate(J,xk);
break;
case 2:
printf("输入要回收分区的作业名");
scanf("%*c%c",&J);
reclaim(J);
break;
case 3:
printf("输出空闲区表:\n起始地址 分区长度 标志\n");
for (i=0;i <m;i++)
printf("%5.0f%10.0f%6d\n",free_table[i].address,free_table[i].length,free_table [i].flag);
printf("按任意键,输出已分分区表\n");
getch();
printf("输出已分分区表:\n起始地址 分区长度 标志\n");
for (i=0;i <n;i++)
if (used_table[i].flag!=0)
printf("%6.0f%9.0f%6d\n",used_table[i].address,used_table[i].length,used_table [i].flag);
else
printf("%6.0f%9.0f%6d\n",used_table[i].address,used_table[i].length,used_table [i].flag);
break;
default:printf("没有该选项\n");
}
}
}