#include"stdio.h"
#include"stdlib.h"
#include "string.h"
#define WAIT 1
#define READY 2
#define FINISH 3

int Available=3;/*剩余資源數量*/
int Max[3]={10,4,9};/*每個進程所需的最大資源量*/
int Allocation[3]={5,2,2};/*已分配的資源數*/
int Need[3]={5,2,7};/*還需要的資源*/
int s[3];/*記錄安全隊列*/
int state[3]={READY,READY,READY};/*每種資源的初始狀態*/

void circle(int total,int Work,int Finish[3])/*循環體*/
{
  int i;
  for(i=0;i<3;i++)
 {
  if(Finish[i]==0)
  if(Need[i]<=Work)/*察看現有資源能滿足那個進程的運行，以產生安全隊列*/
    {
      Work=Work+Allocation[i];/*滿足某一個進程執行的要求，可以假設釋放此進程所占有的資源,以供判斷其他進程能否執行*/
      Finish[i]=1;
      s[total]=i;/*將安全隊列的一項存入數組*/
      circle(total+1,Work,Finish);/*將現有的狀態作為參數，傳入下一個循環*/
    }
  }
}

int savecheck()/*此函數進行安全性測試*/
{
  int i;
  FILE  *fp;
  int flag=1;
  int Work=Available;
  int Finish[3]={0,0,0};/*用來標記是否能運行*/
  circle(0,Work,Finish);/*由初始狀態進入循環體*/
  for(i=0;i<3;i++)/*察看所有進程再次種資源分配情況下是否能安全結束*/
   {
    if(Finish[i]==0)
    flag=0;
   }
  if(flag==1)/*如果都能，打印此時的系統是安全的*/
  {fp=fopen("lock.txt","a+");
   fprintf(fp,"The system is save.\n");
   fclose(fp);
   for(i=0;i<3;i++)/*打印安全隊列*/
   {
   if(state[i]!=FINISH)
   fp=fopen("lock.txt","a+");
   fprintf(fp,"p%d  ",s[i]);
   fclose(fp);
   } 
   fp=fopen("lock.txt","a+");
   fprintf(fp,"\n");
   fclose(fp);
   return 1;
  }
  else
  {fp=fopen("lock.txt","a+");
   fprintf(fp,"The system is unsave.\n");/*否則是不安全的*/
   fclose(fp);
   return 0;
  }
}

void yhj(int n,int r)/*此函數為銀行家算法*/
{
  int savety;
  FILE  *fp;
  if(r<=Need[n])
  {
    if(r<=Available)
     {
       Available=Available-r;/*試探著從空閑資源中減去要分配的資源數*/
       Allocation[n]=Allocation[n]+r;/*將資源數加到已分配資源中*/
       Need[n]=Need[n]-r;/*還需資源數減去分配的資源*/
       savety=savecheck();/*對這種分配方案進行安全性測試*/
       if(savety==0)
       {
        Available=Available+r;/*savety變量為零，表明沒通過安全性測試，將分配的資源還回去*/
        Allocation[n]=Allocation[n]-r;
        Need[n]=Need[n]+r;
        state[n]=WAIT;/*將此進程掛起*/
        fp=fopen("lock.txt","a+");
        fprintf(fp,"pcb%d is hanging up.\n",n);
        fclose(fp);
       
       }
       else {fp=fopen("lock.txt","a+");
             fprintf(fp,"Allocate %d resourse.",r);
             fprintf(fp,"pcb%d is running.\n",n);/*通過安全性測試，就運行該進程，將資源真正分配出去*/
             fclose(fp);
            }
            
     }
    else
        { fp=fopen("lock.txt","a+");
          fprintf(fp,"Resourse is not enough.The progress is waiting...\n");/*分配資源超過剩余資源*/
          fclose(fp);
          return;
        }
  }
  else
        { fp=fopen("lock.txt","a+");
          fprintf(fp,"Error,you apply too much resourse.\n");/*申請太多的資源*/
          fclose(fp);
          
          return;
        }
}

void control()
{
 int i,j,r;
 FILE  *fp;
 for(i=0;i<3;i++)
 {
  if(state[i]==READY)
  {
   r=random(Need[i])+1;/*隨機產生一個不大于所需資源的數*/
   yhj(i,r);/*執行銀行家算法，參數為進程號和要分配的資源數*/
   if(Need[i]==0)/*不再需要資源*/
   {
    state[i]=FINISH;/*進程結束*/
    Available=Available+Max[i];/*釋放所占有的資源*/
    fp=fopen("lock.txt","a+");
    fprintf(fp,"pcb%d has finished.\n",i);
    fclose(fp);
    for(j=0;j<3;j++)
    if(state[j]==WAIT)/*將掛起的進程喚醒*/
    state[j]=READY;
   }
   break;
  }
 }
 
}

main()
{
  int sign=1;
  int i,num=0;
  FILE  *fp;
  
  while(sign)/*用sign做循環標記判斷是否繼續作循環*/
  {
   for(i=0;i<3;i++)/*此循環用來查看是否所有的進程都已結束*/
   {if(state[i]!=FINISH)
    control();/*沒有結束，就執行control()函數，控制進程的執行*/
   else num++;}
   if(num==3)/*如果全部結束，打印結束信息*/
   {sign=0;
    fp=fopen("lock.txt","a+");
    fprintf(fp,"All progress are finished.\n");
    fclose(fp);
    }
  }
  
  getch();
}