模拟内存分配

操作系统的上机实验报告代码，这里分享给大家：

#include<stdio.h>#include<stdlib.h>#define PROCESS_NAME_LEN 32        /*进程名称的最大长度*/#define MIN_SLICE    10            /*最小碎片的大小*/#define DEFAULT_MEM_SIZE 1024       /*默认内存的大小*/#define DEFAULT_MEM_START 0        /*默认内存的起始位置*//* 内存分配算法 */#define MA_FF 1#define MA_BF 2#define MA_WF 3/*描述每一个空闲块的数据结构*/struct free_block_type{    int size;    int start_addr;    struct free_block_type *next;};/*指向内存中空闲块链表的首指针*/struct free_block_type *free_block;/*每个进程分配到的内存块的描述*/struct allocated_block{    int pid;            /*进程pid*/    int size;           /*内存块大小*/    int start_addr;     /*开始地址*/    char process_name[PROCESS_NAME_LEN]; /*进程名*/    struct allocated_block *next;};/*进程分配内存块链表的首指针*/struct allocated_block *allocated_block_head = NULL;int mem_size=DEFAULT_MEM_SIZE;        /*内存大小*/int ma_algorithm = MA_FF;            /*当前分配算法*/static int pid = 0;                    /*初始pid*/int flag = 0;                      /*设置内存大小标志*//*函数声明*/struct free_block_type* init_free_block(int mem_size);void display_menu();int set_mem_size();void set_algorithm();void rearrange(int algorithm);void rearrange_FF();void rearrange_BF();void rearrange_WF();int new_process();int allocate_mem(struct allocated_block *ab);void kill_process();int free_mem(struct allocated_block *ab);int dispose(struct allocated_block *free_ab);int display_mem_usage();void do_exit();void swap(int* , int*);struct allocated_block *find_process(int);struct allocated_block *find_process(int pid){    struct allocated_block *p;    p = allocated_block_head;    while(p!= NULL)    {        if(p->pid == pid)        {            return p;        }        p = p->next;    }    return NULL;}void swap(int *a,int  *b){    int tmp;    tmp = *a;    *a = *b;    *b = tmp;}void do_exit(){}int main(){    int a = 10;    int b = 20;    swap(&a,&b);    char choice;    pid=0;    free_block = init_free_block(mem_size); //初始化空闲区    for(;;)    {        display_menu(); //显示菜单        fflush(stdin);        choice=getchar();   //获取用户输入        switch(choice)        {            case '1': set_mem_size(); break;    //设置内存大小            case '2': set_algorithm();flag=1; break;    //设置分配算法            case '3': new_process(); flag=1; break; //创建新进程            case '4': kill_process();flag=1; break; //删除进程            case '5': display_mem_usage(); flag=1; break;   //显示内存使用            case '0': do_exit(); exit(0);       //释放链表并退出            default: break;        }        getchar();    }}/*初始化空闲块，默认为一块，可以指定大小及起始地址*/struct free_block_type* init_free_block(int mem_size){    struct free_block_type *fb;    fb=(struct free_block_type *)malloc(sizeof(struct free_block_type));    if(fb==NULL)    {        printf("No mem\n");        return NULL;    }    fb->size = mem_size;    fb->start_addr = DEFAULT_MEM_START;    fb->next = NULL;    return fb;}/*显示菜单*/void display_menu(){    printf("\n");    printf("1 - Set memory size (default=%d)\n", DEFAULT_MEM_SIZE);    printf("2 - Select memory allocation algorithm\n");    printf("3 - New process \n");    printf("4 - Terminate a process \n");    printf("5 - Display memory usage \n");    printf("0 - Exit\n");}/*设置总内存的大小*/int set_mem_size(){    int size;    if(flag!=0)  //防止重复设置    {        printf("Cannot set memory size again\n");        return 0;    }    printf("Total memory size =");    scanf("%d", &size);    if(size>0)    {        mem_size = size;        free_block->size = mem_size;    }    flag=1;    return 1;}/* 设置当前的分配算法 */void set_algorithm(){    int algorithm;    printf("\t1 - First Fit\n");    printf("\t2 - Best Fit \n");    printf("\t3 - Worst Fit \n");    scanf("%d", &algorithm);    if(algorithm>=1 && algorithm <=3)        ma_algorithm=algorithm;    //按指定算法重新排列空闲区链表    rearrange(ma_algorithm);}/*按指定的算法整理内存空闲块链表*/void rearrange(int algorithm){    switch(algorithm)    {        case MA_FF:  rearrange_FF(); break;        case MA_BF:  rearrange_BF(); break;        case MA_WF: rearrange_WF(); break;    }}/*按FF算法重新整理内存空闲块链表*/void rearrange_FF(){    struct free_block_type *tmp, *work;    printf("Rearrange free blocks for FF \n");    tmp = free_block;    while(tmp!=NULL)    {        work = tmp->next;        while(work!=NULL)        {            if( work->start_addr < tmp->start_addr) /*地址递增*/            {                printf("%d %d",work->start_addr,tmp->start_addr);                swap(&work->start_addr, &tmp->start_addr);                swap(&work->size, &tmp->size);                printf("%d %d",work->start_addr,tmp->start_addr);            }            work=work->next;        }        tmp=tmp->next;    }}/*按BF算法重新整理内存空闲块链表*/void rearrange_BF(){    //请自行补充    struct free_block_type *tmp, *work;    printf("Rearrange free blocks for BF \n");    tmp = free_block;    while(tmp!=NULL)    {        work = tmp->next;        while(work!=NULL)        {            if( work->size < tmp->size) /*内存大小递增*/            {                printf("%d %d",work->start_addr,tmp->start_addr);                swap(&work->start_addr, &tmp->start_addr);                swap(&work->size, &tmp->size);                printf("%d %d",work->start_addr,tmp->start_addr);            }            work=work->next;        }        tmp=tmp->next;    }}/*按WF算法重新整理内存空闲块链表*/void rearrange_WF(){    //请自行补充    struct free_block_type *tmp, *work;    printf("Rearrange free blocks for WF \n");    tmp = free_block;    while(tmp!=NULL)    {        work = tmp->next;        while(work!=NULL)        {            if( work->size > tmp->size) /*地址递减*/            {                swap(&work->start_addr, &tmp->start_addr);                swap(&work->size, &tmp->size);            }            work=work->next;        }        tmp=tmp->next;    }}/*创建新的进程，主要是获取内存的申请数量*/int new_process(){    struct allocated_block *ab;    int size;    int ret;    ab=(struct allocated_block *)malloc(sizeof(struct allocated_block));    if(!ab)    {        exit(-5);    }    ab->next = NULL;    pid++;    sprintf(ab->process_name, "PROCESS-%02d", pid);    ab->pid = pid;    printf("Memory for %s:", ab->process_name);    scanf("%d", &size);    if(size>0)    {        ab->size=size;    }    ret = allocate_mem(ab);  /* 从空闲区分配内存，ret==1表示分配ok*/    /*如果此时allocated_block_head尚未赋值，则赋值*/    if((ret==1) && (allocated_block_head == NULL))    {        allocated_block_head=ab;        return 1;    }/*分配成功，将该已分配块的描述插入已分配链表*/    else if (ret==1)    {        ab->next=allocated_block_head;        allocated_block_head=ab;        return 2;    }    else if(ret==-1) /*分配不成功*/    {        printf("Allocation fail\n");        free(ab);        return -1;    }    return 3;}/*分配内存模块*/int allocate_mem(struct allocated_block *ab){    struct free_block_type *fbt, *pre;    int request_size=ab->size;    fbt = pre = free_block;    while(fbt!=NULL)    {        if(fbt->size>=request_size)/*分配后空闲空间足够大，则分割*/        {            //自行补充********            ab->start_addr = fbt->start_addr;            fbt->start_addr += request_size;            fbt->size-= request_size;            return 1;        }        pre = fbt;        fbt = fbt->next;    }    return -1;}/*删除进程，归还分配的存储空间，并删除描述该进程内存分配的节点*/void kill_process(){    struct allocated_block *ab;    int pid;    printf("Kill Process, pid=");    scanf("%d", &pid);    ab=find_process(pid);    if(ab!=NULL)    {        free_mem(ab); /*释放ab所表示的分配区*/        dispose(ab);  /*释放ab数据结构节点*/    }}/*将ab所表示的已分配区归还，并进行可能的合并*/int free_mem(struct allocated_block *ab){    int algorithm = ma_algorithm;    struct free_block_type *fbt, *pre, *work;    fbt=(struct free_block_type*) malloc(sizeof(struct free_block_type));    if(!fbt)    {        return -1;    }    fbt->size = ab->size;    fbt->start_addr = ab->start_addr;    /*插入到空闲区链表的头部并将空闲区按地址递增的次序排列*/    fbt->next = free_block;    free_block=fbt;    rearrange(MA_FF);    pre=free_block;    while(pre!=NULL)    {        work = pre->next;        if(work!=NULL)        {            /*如果当前空闲区与后面的空闲区相连，则合并*/            if(pre->start_addr+pre->size == work->start_addr)            {                pre->size += work->size;                pre->next = work->next;                free(work);                continue;           }        }        pre = pre->next;    }    rearrange(algorithm); /*重新按当前的算法排列空闲区*/    return 1;}/*释放ab数据结构节点*/int dispose(struct allocated_block *free_ab){    struct allocated_block *pre, *ab;    if(free_ab == allocated_block_head) /*如果要释放第一个节点*/    {        allocated_block_head = allocated_block_head->next;        free(free_ab);        return 1;    }    pre = allocated_block_head;    ab = allocated_block_head->next;    while(ab!=free_ab)    {        pre = ab;  ab = ab->next;    }    pre->next = ab->next;    free(ab);    return 2;}int display_mem_usage(){    struct free_block_type *fbt=free_block;    struct allocated_block *ab=allocated_block_head;    if(fbt==NULL)        return(-1);    printf("----------------------------------------------------------\n");    /* 显示空闲区 */    printf("Free Memory:\n");    printf("%20s %20s\n", "      start_addr", "       size");    while(fbt!=NULL)    {        printf("%20d %20d\n", fbt->start_addr, fbt->size);        fbt=fbt->next;    }    /* 显示已分配区 */    printf("\nUsed Memory:\n");    printf("%10s %20s %10s %10s\n", "PID", "ProcessName", "start_addr", " size");    while(ab!=NULL)    {        printf("%10d %20s %10d %10d\n", ab->pid, ab->process_name, ab->start_addr, ab->size);        ab=ab->next;    }    printf("----------------------------------------------------------\n");    return 0;}

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