操作系统--内存管理

#include "stdio.h" #define MIN_SLICE 10 /*最小碎片的大小*/ #define MEM_SIZE 1024 /*默认内存的大小*/ #define 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 int mem_size=MEM_SIZE; /*内存大小*/ int ma_alg = MA_FF; /*当前分配算法*/ static int pid=0; /*初始pid*/ /*内存空闲分区的描述*/ /*描述空闲分区的数据结构*/ typedef struct free_block_type { int size; int start_addr; struct free_block_type *next; }f_Node,*f_block; /*指向内存中空闲分区链表的首指针*/ f_block free_block=NULL; /*描述已分配的内存块*/ /*分配给进程的分区的描述*/ typedef struct allocated_block { int pid; int size; int start_addr; struct allocated_block *next; }a_Node,*all_block; /*进程分配内存块链表的首指针*/ all_block allocated_area = NULL; void swap(int *a,int *b) { int c; c=*a; *a=*b; *b=c; } /*初始化空闲块，默认为6块*/ init_free_block() { f_Node *s; int i,n; int size=MEM_SIZE; int start=0; printf("How many blocks do you want to divided?"); scanf("%d",&n); for(i=1;i<n;i++) { s=(f_Node *)malloc(sizeof(f_Node)); s->size=size/2; s->start_addr=start; size=s->size; start=start+s->size; s->next=free_block; free_block=s; } s=(f_Node *)malloc(sizeof(f_Node)); s->size=MEM_SIZE-start; s->start_addr=start; s->next=free_block; free_block=s; } rearange(int maalgorithm) {if(maalgorithm==1)rearrange_FF(); if(maalgorithm==2)rearrange_BF(); if(maalgorithm==3)rearrange_WF(); } /* 设置当前的分配算法 */ set_algorithm() { int alg; printf("choice the algorithm:\n"); printf("\t1 - First Fit\n"); printf("\t2 - Best Fit \n"); printf("\t3 - Worst Fit \n"); scanf("%d", &alg); if(alg>=1 && alg <=3) {ma_alg=alg; /*按指定算法重新排列空闲区链表*/ rearange(ma_alg); } } /*按FF算法重新整理内存空闲块链表*/ rearrange_FF() { f_Node *tmp, *work; printf("Rearrange free blocks for FF \n"); tmp = free_block; /*把原来的空闲区链表按地址递增的顺序重新排列*/ while(tmp!=NULL) { work = tmp->next; while(work!=NULL) { if( work->start_addr < tmp->start_addr) /*地址递增*/ { swap(&work->start_addr, &tmp->start_addr); swap(&work->size, &tmp->size); } else work=work->next; } tmp=tmp->next; } } /*按BF算法重新整理内存空闲块链表*/ rearrange_BF() { f_Node *tmp, *work; printf("Rearrange free blocks for BF \n"); tmp = free_block; /*把原来的空闲区链表按大小递增的顺序重新排列*/ while(tmp!=NULL) { work = tmp->next; while(work!=NULL) { if( work->size < tmp->size) /*大小递增*/ { swap(&work->start_addr, &tmp->start_addr); swap(&work->size, &tmp->size); } else work=work->next; } tmp=tmp->next; } } /*按WF算法重新整理内存空闲块链表*/ rearrange_WF() { f_Node *tmp, *work; printf("Rearrange free blocks for WF \n"); tmp = free_block; /*把原来的空闲区链表按大小递减的顺序重新排列*/ while(tmp!=NULL) { work = tmp->next; while(work!=NULL) { if( work->size > tmp->size) /*大小递减*/ { swap(&work->start_addr, &tmp->start_addr); swap(&work->size, &tmp->size); } else work=work->next; } tmp=tmp->next; } } /*分配内存模块*/ int allocate_mem(struct allocated_block *ab) { f_Node *fbt, *pre; int request_size=ab->size; fbt = pre = free_block; while(fbt!=NULL) { if(fbt->size>=request_size) { if((fbt->size-request_size)>MIN_SLICE) { ab->start_addr=fbt->start_addr; fbt->size=fbt->size-request_size; fbt->start_addr=fbt->start_addr+request_size; } else { ab->start_addr=fbt->start_addr; ab->size=fbt->size; if(fbt==free_block) { free_block=fbt->next; free(fbt); } else { pre->next=fbt->next; free(fbt); } } return 1; } pre=fbt; fbt=fbt->next; } return -1; } /*创建新的进程，主要是获取内存的申请数量*/ new_process() { char ch; a_Node *ab; int size; int ret; ab=(a_Node *)malloc(sizeof(a_Node)); if(!ab) exit(-5); ab->next = NULL; pid++; printf(" \nPROCESS-%02d\n", pid); ab->pid = pid; printf("Input the process' size:"); scanf("%d", &size); if(size>0) ab->size=size; set_algorithm(); ret = allocate_mem(ab); /* 从空闲区分配内存，ret==1表示分配ok*/ /*如果此时已分配分区链表尚未空，则把ab作为第一个分配的分区*/ if (ret==1) { ab->next=allocated_area; allocated_area=ab; printf("process %d is comleted!\n",pid); display_mem_usage(); printf("Do you want to receive its space?"); ch=getche(); if(ch=='y') free_mem(ab); else if(ch=='n') {printf("\n"); getch(); } return 1; } else if(ret==-1) { /*分配不成功*/ printf("Allocation fail\n"); free(ab); return -1; } } /*将ab所表示的分区归还，并进行可能的合并*/ int free_mem(struct allocated_block *ab) { int alg = ma_alg; f_Node *fbt,*work; fbt=(f_Node *)malloc(sizeof(f_Node)); 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_FF(); fbt=free_block; while(fbt!=NULL) { if(ab->start_addr==fbt->start_addr) { if(fbt->start_addr+fbt->size==fbt->next->start_addr) { fbt->size+=fbt->next->size; work=fbt->next; fbt->next=fbt->next->next; free(work); break; } fbt=fbt->next; } } allocated_area=ab->next; free(ab); rearange(ma_alg); return 1; } /* 显示当前内存的使用情况，包括空闲区的情况和已经分配的情况 */ display_mem_usage() { f_Node *fbt=free_block; a_Node *ab=allocated_area; 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 %10s %10s\n", "PID", "start_addr", " size"); while(ab!=NULL) { printf("%10d %10d %10d\n", ab->pid, ab->start_addr, ab->size); ab=ab->next; } printf("----------------------------------------------------------\n"); return 0; } main() { char c; int i,j; printf("The memory's size is 1024\n"); init_free_block(); display_mem_usage(); while(1) {printf("\nDoyou want to creat new process?\n"); c=getche(); getch(); if(c=='Y'||c=='y') {new_process(); display_mem_usage(); getch(); } else if(c=='n'||c=='N') break; } printf("\nIt's Over!!!"); getch(); }