suffle.c

银行家算法的实现

#include<stdio.h>

#define state_ready		0
#define state_waiting	-1
#define state_finish	1
#define resource		10
#define process			4
#define inputfile		"in.txt"
#define outputfile		"out.txt"
#define maxapply		20
typedef struct pcb
{
	int name ;
	int state;
	int current[resource];
	int claim[resource];
	int allocation[resource];
	int flag; 
};

typedef struct application
{
	int name;
	int number[resource];
	int state;
};

struct application apply[maxapply];
struct pcb thepcb[process];
int amount[resource];
int avail[resource];
int napply;
FILE*out;
/*从in.txt中度入资源总量和各个分配请求*/
int initiate()
{
	FILE*fp;
	int i,j,n;
	fp=fopen(inputfile,"r");
	for(i=0;i<resource;i++)
	{
		fscanf(fp," %d",&amount[i]);
		avail[i]=amount[i];
	}
	fscanf(fp," %d",&napply);
	for(i=0;i<napply;i++)
	{
		fscanf(fp," %d",&n);
		if(n>=process)
			return 1;
		apply[i].name=n;
		for(j=0;j<resource;j++)
			fscanf(fp," %d",&apply[i].number[j]);
		apply[i].state=0;
	}

	for(i=0;i<process;i++)
	{
		for(j=0;j<resource;j++)
		{
			thepcb[i].allocation[j]=0;
			thepcb[i].current[0]=0;
		}
		thepcb[i].name=i;
		thepcb[i].state=state_ready;
		thepcb[i].flag=0;
	}
	for(i=0;i<napply;i++)
	{
		n=apply[i].name;
		for(j=0;j<resource;j++)
			thepcb[n].claim[j]=thepcb[n].claim[j]+apply[i].number[j];
	}
	for(i=0;i<process;i++)
		for(j=0;j<resource;j++)
			if(thepcb[i].claim[j]>amount[j])
				return 1;
	fclose(fp);
	return 0;
}
/*把资源请求读入pcb表*/
void readapply(void)
{
	int i,j,n;
	for(i=0;i<napply;i++)
	{
		n=apply[i].name;
		if(apply[i].state==1)
			continue;
		if(thepcb[n].state==state_waiting)
			continue;
		thepcb[n].state=state_waiting;
		apply[i].state=1;
		for(j=0;j<resource;j++)
			thepcb[n].current[j]=apply[i].number[j];
	}
}

/*找到以完成的进程，释放资源*/
void checkfinish()
{
	int i,k;
	for(i=0;i<process;i++)
	{
		for(k=0;k<resource;k++)
			if(thepcb[i].allocation[k]<thepcb[i].claim[k])
				break;
		if(k==resource)
		{
			for(k=0;k<resource;k++)
			{
				avail[k]=avail[k]+thepcb[i].allocation[k];
				thepcb[i].allocation[k]=0;
			}
			thepcb[i].state=state_finish;
			fprintf(out,"process %d finished\n",i);
			printf("process %d finished\n",i);
		}
	}
}
int suffle()
{
	int i,k;
	for(i=0;i<process;i++)
	{
		if(thepcb[i].state==state_waiting)
		{
			for(k=0;k<resource;k++)
				if(thepcb[i].current[k]>avail[k])
					break;
			if(k==resource)
			{
				fprintf(out,"process %d allocated ",i);
				printf("process %d allocated ",i);
				thepcb[i].state=state_ready;
				for(k=0;k<resource;k++)
				{
					fprintf(out," %d",thepcb[i].current[k]);
					printf(" %d",thepcb[i].current[k]);
					avail[k]=avail[k]-thepcb[i].current[k];
					thepcb[i].current[k]=0;
				}
				fprintf(out,"\n");
				printf("\n");
			}
		}
	}
	return 0;
}
int main()
{
	int i;
	/*banker*/
	out=fopen(outputfile,"w");
	if(initiate())
		return 0;
	while(i!=process)
	{
		readapply();
		suffle();
		checkfinish();
		for(i=0;i<process;i++)
			if(thepcb[i].state!=state_finish)
				break;
	}
	return 0;
}