模拟操作系统动态内存管理（c实现）

操作系统对内存申请与释放（对连续的区域合并）的模拟

#include <stdio.h>
#include <stdlib.h>
#define N 10      //预设的内碎片的最小值
#define M_set 1024//预设的内存大小

struct mem_block
{
    int num;
    int addr;
    int length;
    mem_block *next;
};
typedef mem_block* point;

int numcal_M=1;//内存id
int numcal_P=1;//进程id

void create(point &pHead);
void init_get_size(point pHead);
void insert_P(point pHead,int addr,int siz);
void sort_size(point &pHead);//small to big
void sort_addr(point &pHead);
void apply(point M_pHead,point P_pHead);
void chick_conn(point pHead);
void insert_M(point pHead,int addr,int siz);
void free(point P_pHead,point M_pHead);
void print(point pHead);
void destory(point pHead);
int main()
{
    printf("                    *********************************************
");
    printf("                    **         内存管理系统 (最佳适应算法)     **
");
    printf("                    *********************************************
");
    point mem;
    create(mem);
    init_get_size(mem);

    point prog;
    create(prog);

    int op=-1;
    while(1)
    {
        printf("

请输入要进行的操作：
1.申请内存 2.释放内存 3.显示当前内存情况 4.显示被申请走的内存块 0.退出操作
");
        scanf("%d",&op);
        switch(op)
        {
        case 1:
            apply(mem,prog);
            break;
        case 2:
            free(prog,mem);
            break;
        case 3:
            sort_addr(prog);
            printf("内存号     起始地址       内存大小
");
            print(mem);
            break;
        case 4:
            printf("进程号     起始地址       内存大小
");
            print(prog);
            break;
        case 0:
            destory(mem);
            destory(prog);
            exit(0);
        default:
            printf("非法操作
");
            break;
        }
    }
    return 0;
}
void create(point &pHead)
{
    pHead = (point)malloc(sizeof(mem_block));
    pHead ->num=0;
    pHead->addr=0;
    pHead->length = 0;
    pHead->next=NULL;
    return;
}

void insert_P(point pHead,int addr,int siz)
{
    point pPro=(point)malloc(sizeof(mem_block));
    pPro->length=siz;
    pPro->addr=addr;
    pPro->next=NULL;
    pPro->num=numcal_P;
    numcal_P++;

    point pCur = pHead;
    while(pCur->next!=NULL)
        pCur=pCur->next;
    pCur->next=pPro;
    return;
}
void sort_size(point &pHead)//small to big
{
    point pCur_i=pHead,pCur_j;
    int num,addr,siz;
    while(pCur_i->next!=NULL)
    {
        pCur_i=pCur_i->next;
        pCur_j=pCur_i;
        while(pCur_j->next!=NULL)
        {
            pCur_j=pCur_j->next;
            if(pCur_j->length  < pCur_i->length)
            {
                num=pCur_i->num;
                addr=pCur_i->addr;
                siz=pCur_i->length;

                pCur_i->num=pCur_j->num;
                pCur_i->addr=pCur_j->addr;
                pCur_i->length=pCur_j->length;

                pCur_j->num=num;
                pCur_j->addr=addr;
                pCur_j->length=siz;
            }
        }
    }
}
void sort_addr(point &pHead)
{
    point pCur_i=pHead,pCur_j;
    int num,addr,siz;
    while(pCur_i->next!=NULL)
    {
        pCur_i=pCur_i->next;
        pCur_j=pCur_i;
        while(pCur_j->next!=NULL)
        {
            pCur_j=pCur_j->next;
            if(pCur_j->addr  < pCur_i->addr)
            {
                num=pCur_i->num;
                addr=pCur_i->addr;
                siz=pCur_i->length;

                pCur_i->num=pCur_j->num;
                pCur_i->addr=pCur_j->addr;
                pCur_i->length=pCur_j->length;

                pCur_j->num=num;
                pCur_j->addr=addr;
                pCur_j->length=siz;
            }
        }
    }
}
void apply(point M_pHead,point P_pHead)
{
    sort_size(M_pHead);
    int siz;
    printf("请输入要申请内存的大小
");
    scanf("%d",&siz);
    point pCur=M_pHead;
    int flag=1;
    while(pCur->next!=NULL)
    {

        if(pCur->next->length-siz<=N&&pCur->next->length>=siz)
        {
            insert_P(P_pHead,pCur->next->addr,pCur->next->length);
            pCur->next=pCur->next->next;

            flag=0;
            break;
        }
        else if(pCur->next->length-siz>N)
        {

            insert_P(P_pHead,pCur->next->addr,siz);
            pCur->next->length-=siz;
            pCur->next->addr+=siz;
            flag=0;
            break;
        }
        pCur=pCur->next;
    }
    if(flag)  printf("哪有那么大的空间呀，插不进去
");
    else      printf("分配成功
");
    return;

}

void init_get_size(point pHead)
{
    point pPro=(point)malloc(sizeof(mem_block));

    pPro->length=M_set;
    pPro->addr=0;
    pPro->next=NULL;
    pPro->num=numcal_M;

    numcal_M++;
    pHead->next=pPro;
    return;
}
void chick_conn(point pHead)
{
   point i,j;
   for(i=pHead;i->next!=NULL;i=i->next)
        for(j=pHead;j->next!=NULL;j=j->next)
   {
       if( (j->next->addr) == (i->next->addr) + (i->next->length) )
       {
           i->next->length+=j->next->length;
           j->next=j->next->next;
           break;
       }
   }
   return;
}

void insert_M(point pHead,int addr,int siz)
{

    point pCur=pHead;
    int flag=0;
    while(pCur->next!=NULL)
    {
        if(pCur->next->addr+pCur->next->length==addr)
        {
            flag=1;
            pCur->next->length+=siz;
            break;
        }
        pCur=pCur->next;
    }
    if(!flag)
    {
        point pPro=(point)malloc(sizeof(mem_block));
        pPro->length=siz;
        pPro->addr=addr;
        pPro->next=NULL;
        pPro->num=numcal_M;
        numcal_M++;

        pCur->next=pPro;

    }

   chick_conn(pHead);
    printf("释放成功
");
    return;
}
void free(point P_pHead,point M_pHead)
{
    int prog_num =0;
    printf("请输入要释放的内存块号
");
    scanf("%d",&prog_num);
    point pCur = P_pHead;
    int flag=1;
    while(pCur->next!=NULL)
    {
        if(pCur->next->num==prog_num)
        {
            flag=0;
            insert_M(M_pHead,pCur->next->addr,pCur->next->length);
            pCur->next=pCur->next->next;
            break;
        }
        pCur=pCur->next;
    }
    if(flag)
        printf("亲，这个内存号不存在呀，要不你先按4，看看情况？
");
}
void print(point pHead)
{
    int flg=0;
    point pCur=pHead;
    while(pCur->next!=NULL)
    {
        pCur=pCur->next;
        printf("%3d%12d%15d
",pCur->num,pCur->addr,pCur->length);
        flg=1;
    }
    if(!flg)
        printf("

         空链表，没有数据    
");
    printf("
");
    return;
}
void destory(point pHead)
{
    point pNext=pHead->next;
    while(pHead->next!=NULL)
    {
        free(pHead);
        pHead=pNext;
        pNext=pHead->next;
    }
    free(pHead);
    pHead = NULL;
    printf("撤销成功
");
}