内存分配算法.c

内存分配算法,用c实现内存的管理分配,属于操作系统范畴

#include "stdio.h"
#include "stdlib.h"
#include "string.h"
#define MAX 32767
typedef struct node   
{
   int address,size;
   struct node *next;
}RECT;
RECT *assignment(RECT *head,int application);
void acceptment1(RECT *head,RECT *back1);
void acceptment2(RECT *head,RECT *back1) ;
int backcheck(RECT *head,RECT *back1);
void print(RECT *head);
RECT *head,*back,*assign1,*p;
int application1,maxblocknum;
char way;
/*主函数*/
main()
{
   char choose[10];
   int check;
   head=malloc(sizeof(RECT)); 
   p=malloc(sizeof(RECT));
   head->size=MAX;
   head->address=0;
   head->next=p;
   maxblocknum=1;
   p->size=MAX;
   p->address=0;
   p->next=NULL;
   print(head);  
   printf("Enter the way(best or first(b/f)\n");
   scanf("%c",&way);
   do{
      printf("Enter the assign or accept(as/ac)\n");
      scanf("%s",choose); /*选择分配或回收*/
      if(strcmp(choose,"as")==0) 
      {
	 printf("Input application:\n");
	 scanf("%d",&application1);
	 assign1=assignment(head,application1);
	 if(assign1->address==-1)
	    printf("Too large application!,assign fails!!\n\n");
	 else
	    printf("Success!!ADDRESS=%5d\n",assign1->address); 
	 print(head);
      }
      else
	 if(strcmp(choose,"ac")==0) /*回收*/
	 {
	    back=malloc(sizeof(RECT));
	    printf("Input Adress and Size!!\n");
	    scanf("%d%d",&back->address,&back->size);
	    check=backcheck(head,back); 
	    if(check==1)
	    {
	       if(tolower(way)=='f')/*首先适应算法*/
		  acceptment1(head,back); /*首先适应*/
	       else
		  acceptment2(head,back);/*最佳适应*/
	       print(head);
	    }
	 }
   }while(!strcmp(choose,"as")||!strcmp(choose,"ac"));
}
/*分配函数*/
RECT *assignment(RECT *head,int application)
{
   RECT *after,*before,*assign;
   assign=malloc(sizeof(RECT)); 
   assign->size=application;
   assign->next=NULL;
   if(application>head->size||application<=0)
      assign->address=-1; /*申请无效*/
   else
   {
      before=head;
      after=head->next;
      while(after->size<application)
      {
	 before=before->next;
	 after=after->next;
      }
      if(after->size==application) /*结点大小等于申请大小则完全分配*/
      {
	 if(after->size==head->size)
	    maxblocknum--;
	 before->next=after->next;
	 assign->address=after->address;
	 free(after);
      }
      else
      {
	 if(after->size==head->size) maxblocknum--;
	 after->size=after->size-application; /*大于申请空间则截取相应大小分配*/
	 assign->address=after->address+after->size;
	 if(tolower(way)=='b')
	 {
	    before->next=after->next;
	    back=after;
	    acceptment2(head,back);
	 }
      }
      if(maxblocknum==0) 
      {
	 before=head;
	 head->size=0;
	 maxblocknum=1;
	 while(before!=NULL)
	 {
	    if(before->size>head->size)
	    {
	       head->size=before->size;
	       maxblocknum=1;
	    }
	    else
	       if(before->size==head->size)
		  maxblocknum++;
	    before=before->next;
	 }
      }
   }
   assign1=assign;
   return assign1; 
}
void acceptment1(RECT *head,RECT *back1)/*首先适应*/
{
   RECT *before,*after;
   int insert;
   before=head;
   after=head->next;
   insert=0;
   while(!insert) 
   {
      if((after==NULL)||
	 ((back1->address<=after->address)&&
	   (back1->address>=before->address)))
      {
	 before->next=back1;
	 back1->next=after;
	 insert=1;
      }
      else
      {
	 before=before->next;
	 after=after->next;
      }
   }
   if(back1->address==before->address+before->size)
   {
      before->size=before->size+back1->size;
      before->next=back1->next;
      free(back1);
      back1=before;
   }
   if(after!=NULL&&(after->address==back1->address+back1->size))
   {  
      back1->size=back1->size+after->size;
      back1->next=after->next;
      free(after);
   }
   if(head->size<back1->size) 
   {
      head->size=back1->size;
      maxblocknum=1;
   }
   else
      if(head->size==back1->size)
	 maxblocknum++;
}
/*最佳适应*/
void acceptment2(RECT *head,RECT *back1)
{
   RECT *before,*after;
   int insert ;
   insert=0;
   before=head;
   after=head->next;
   if(head->next==NULL) 
   {
      head->size=back1->size;
      head->next=back1;
      maxblocknum++;
      back1->next=NULL;
   }
   else
   {
      while(after!=NULL) 
      if(back1->address==after->size+after->address)
      {
	 before->next=after->next;
	 back->size=after->size+back1->size;
	 free(after);
	 after=NULL;
      }
      else
      {
	 after=after->next;
	 before=before->next;
      }
      before=head;
      after=head->next;
      while(after!=NULL)
      if(after->address==back1->size+back1->address) 
      {
	 back1->size=back1->size+after->size;
	 before->next=after->next;
	 free(after);
	 after=NULL;
      }
      else
      {
	 before=before->next;
	 after=after->next;
      }
      before=head;
      after=head->next;
      do{
	 if(after==NULL||(after->size>back1->size))
	 {
	    before->next=back1;
	    back1->next=after;
	    insert=1;
	 }
	 else
	 {
	    before=before->next;
	    after=after->next;
	 }
      }while(!insert);
      if(head->size<back1->size) 
      {
	 head->size=back1->size;
	 maxblocknum++;
      }
      else
	 if(head->size==back1->size)
	    maxblocknum++;
   }
}

void print(RECT *head) 
{
   RECT *before,*after;
   int index,k;
   before=head->next;
   index=1;
   if(head->next==NULL)
      printf("NO part for assignment!!\n");
   else
   {
      printf("*****index*******address********end*********size*****\n");
      while(before!=NULL)
      {
	 printf("----------------------------------------------------\n");
	 printf("     %-13d%-13d%-13d%-13d\n",index,before->address,before->address+before->size-1,before->size);
	 printf("----------------------------------------------------\n");
	 index++;
	 before=before->next;
      }
   }
}
int backcheck(RECT *head,RECT *back1)
{
   RECT *before,*after;
   int check=1;
   if(back1->address<0||back1->size<0)
      check=0;
   before=head->next;
   while((before!=NULL)&&check)
      if(((back1->address<before->address)
	 &&(back1->address+back1->size>before->address))
	 ||((back1->address>=before->address)
	&&(back1->address<before->address+before->size)))
	 check=0;
      else
	 before=before->next;
   if(check==0)
      printf("Error input!!\n");
   return check;  
}