mem.c

Linux下载的几个小C程序

#define TRUE 1
#define FALSE 0
#define INVALID -1
#define NULL 0
#define total_instruction 320
#define total_VP 32
typedef struct
{int pn,pfn,counter,time;
}
 p1_type;
 p1_type p1[total_VP];
 struct pfc_struct
{int pn,pfn;
 struct pfc_struct*next;
};
typedef struct pfc_struct pfc_type;
pfc_type pfc[total_VP],*freepf_head,*busypf_head,*busypf_tail;
int diseffect,a[total_instruction];
int page[total_instruction],offset[total_instruction];
void initialize();
void FIFO();
void LRU();
main()
{int s,i,j;
 srand(getpid()*10);
 s=rand()%319;
 for(i=0;i<total_instruction;i+=4)
 {a[i]=s;
  a[i+1]=a[i]+1;
  a[i+2]=rand()%(a[i]+1);
  a[i+3]=a[i+2]+1;
  /*s=rand()*(319-a[i+2])%319+a[i+2]+2;*/
  s=rand()%(319-a[i+2])+a[i+2]+1;
 }
 for(i=0;i<total_instruction;i++)
 {page[i]=a[i]/10;
  offset[i]=a[i]%10;
 }
 for(i=4;i<=32;i++)
 {printf("%2d page frames",i);
  FIFO(i);
  LRU(i);
  printf("\n");
 }
}
void FIFO(total_pf)
int total_pf;
{int i,j;
 pfc_type *p,*t;

  // printf("pzy Debug Information1\n");

 initialize(total_pf);

   //printf("pzy Debug Information2\n");

 busypf_head=busypf_tail=NULL;
 for(i=0;i<total_instruction;i++)
 {if(p1[page[i]].pfn==INVALID)
  {diseffect+=1;
   if(freepf_head==NULL)
   {p=busypf_head->next;
    p1[busypf_head->pn].pfn=INVALID;
    freepf_head=busypf_head;
    freepf_head->next=NULL;
    busypf_head=p;
   }
   p=freepf_head->next;
   freepf_head->next=NULL;
   freepf_head->pn=page[i];
   p1[page[i]].pfn=freepf_head->pfn;
   if(busypf_tail==NULL)
   busypf_head=busypf_tail=freepf_head;
   else
   {busypf_tail->next=freepf_head;
    busypf_tail=freepf_head;
   }
   freepf_head=p;
  }
 }
printf("FIFO:%6.4f",1-(float)diseffect/320);
}
void LRU(total_pf)
int total_pf;
{int min,minj,i,j,present_time;
 initialize(total_pf);
 present_time=0;
 for(i=0;i<total_instruction;i++)
 {if(p1[page[i]].pfn==INVALID)
  {diseffect++;
   if(freepf_head==NULL)
   {min=32767;
    for(j=0;j<total_VP;j++)
    if(min>p1[i].time&&p1[j].pfn!=INVALID)
    {min=p1[j].time;minj=j;}
    freepf_head=&pfc[p1[minj].pfn];
    p1[minj].pfn=INVALID;
    p1[minj].time=-1;
    freepf_head->next=NULL;
   }
   p1[page[i]].pfn=freepf_head->pfn;
   p1[page[i]].time=present_time;
   freepf_head=freepf_head->next;
  }
  else
  p1[page[i]].time=present_time;
  present_time++;
 }
 printf("LRU:%6.4f",1-(float)diseffect/320);
}
void initialize(total_pf)
int total_pf;
{int i;
 diseffect=0;
 for(i=0;i<total_VP;i++)
 {p1[i].pn=i;
  p1[i].pfn=INVALID;
  p1[i].counter=0;
  p1[i].time=-1;
 }
 for(i=1;i<total_pf;i++)
 {pfc[i-1].next=&pfc[i];
  pfc[i-1].pfn=i-1;
 }
 pfc[total_pf-1].next=NULL;
 pfc[total_pf-1].pfn=total_pf-1;
 freepf_head=&pfc[0];
}