实验四

#include <stdio.h>
#include <stdlib.h>
#include <string.h> 
const int CANUSE = 1;
const int CANTUSE = 0;
//#define MSIZE 128;
const int MSIZE = 128;


//内存分区 
struct MZone
{
//空闲区起始地址 
int begin_addr; 
//一个连续空闲区的长度
int length; 
//状态 
int state;
//内存中任务名
char task_name[32]; 
//指向下一个空闲分区
struct MZone *next; 
};

//内存头指针 
struct MZone *Mhead = NULL;

//showmemory函数，显示当前内存分配情况 
void showmemory()
{
struct MZone *Mpoint = Mhead;

printf("内存的使用情况\n");
printf("beginaddr\tlength\tstate\ttask\n"); 

while( NULL!=Mpoint)
{
printf("%dk\t\t",Mpoint->begin_addr);
printf("%dk\t",Mpoint->length);
Mpoint->state?printf("CANUSE\t"):printf("CANTUSE\t");
printf("%s\n",Mpoint->task_name);
Mpoint = Mpoint->next;
} 

system("pause");

}

//memoallocate函数，用于分配内纯 
void memoallocate(void)
{
struct MZone *Mnew = (struct MZone*)malloc(sizeof(struct MZone));
printf("输入要分配内存大小(kb):\n");
scanf("%d",&Mnew->length);
printf("输入任务名:\n");
scanf("%s",&Mnew->task_name);
Minsert(Mnew)?printf("分配内存成功\n"):printf("没有符合大小的空闲分区，内存分配失败。\n"); 
system("pause");
free(Mnew);
}

//Minsert函数，功能插入任务到空闲分区 
int Minsert(struct MZone* Mnew)
{

struct MZone *Zinsert = Mhead;
//flag用于指示是Zinsert到了NULL，既没有内存可以分配 
int flag = 1; 

while( Zinsert->length<Mnew->length || !Zinsert->state)
{
if( NULL!=Zinsert->next )
{
Zinsert = Zinsert->next;
}
else
{ 
Zinsert = Zinsert->next;
break;
}

}

if( NULL==Zinsert ) 
{
return 0;
}

if( MSIZE == Zinsert->begin_addr+Mnew->length )
{
Zinsert->state = CANTUSE;
strcpy(Zinsert->task_name , Mnew->task_name);
Zinsert->next = NULL;
return 1;
}
else
{
struct MZone *Ztail = (struct MZone *)malloc(sizeof(struct MZone));
Zinsert->state = CANTUSE;
strcpy(Zinsert->task_name , Mnew->task_name);
Zinsert->length = Mnew->length;
Zinsert->next = Ztail;

memset( Ztail, 0, sizeof(char)*32 );
Ztail->begin_addr = Zinsert->begin_addr + Mnew->length;
Ztail->state = CANUSE;
Ztail->length = MSIZE - Ztail->begin_addr;
Ztail->next = NULL;

return 1;
}
}

//memoreturn函数，用于回收内存
void memoreturn(void)
{
char tname[32];
printf("输入要收回的任务名\n");
scanf("%s",tname);
Mreturn(tname); 
system("pause"); 
} 

//Mreturn函数，功能回收内存
int Mreturn(char taskname[])
{
struct MZone *front = NULL;
struct MZone *position = Mhead;
struct MZone *tail = Mhead->next;

while( 0!=strcmp(position->task_name,taskname) ) 
{
front = position;
if( NULL!=position->next )
{
position = position->next;
}
else
{
position = NULL;
break;
}
tail = position->next;
}

if( NULL==position )
{
printf("内存中没有此任务！"); 
}
else
{
//不能用CANTUSE 
if( NULL!=tail&&NULL!=front )
{

if( front->state&&tail->state )
{
front->length = front->length + position->length + tail->length;
front->next = tail->next;
free(position);
free(tail);
}
else if( front->state&&!tail->state )
{
front->length = front->length + position->length;
front->next = position->next;
free(position);
}
else if( !front->state&&tail->state )
{
position->length = position->length + tail->length;
memset( position->task_name, 0, sizeof(char)*32 );
position->next = tail->next;
position->state = CANUSE;
free(tail);
}
else if( !front->state&&!tail->state )
{
memset( position->task_name, 0, sizeof(char)*32 );
position->state = CANUSE; 
}
}
else if( NULL!=tail&&NULL==front )
{
if( !tail->state )
{
memset( position->task_name, 0, sizeof(char)*32 );
position->state = CANUSE;
}
else
{
position->length = position->length + tail->length;
position->next = NULL;
free(tail);
}
} 
else if( NULL==tail&&NULL!=front )
{
if(front->state)
{ 
front->length = front->length + position->length;
front->next = NULL;
free(position);
}
else
{
memset( position->task_name, 0, sizeof(char)*32 );
position->state = CANUSE;
}
}
else if( NULL==tail&&NULL==front )
{
memset( position->task_name, 0, sizeof(char)*32 );
position->state = CANUSE; 
}
printf("内存回收成功！\n");
}
}

int main(void)
{
int func_ = 0;

//初始化Mhead 
Mhead = (struct MZone*)malloc(sizeof(struct MZone));
Mhead->begin_addr = 0;
Mhead->length = MSIZE;
Mhead->state = CANUSE;
memset(Mhead->task_name, 0, sizeof(char)*32 );
Mhead->next = NULL;

while( 1 )
{
printf("******************首次适应算法实现主存分配和回收系统（内存MSIZE）***************");
printf("|1:查看内存分配情况\n");
printf("|2:申请分配内存\n");
printf("|3:申请回收内存\n");
printf("|4:退出程序\n");
printf("********************************************************************************");
scanf("%d",&func_);
switch( func_ )
{
case 1 :showmemory();break;
case 2 :memoallocate();break;
case 3 :memoreturn();break; 
case 4 :return 1;
}
system("cls");
} 
}