diskarithmetic.cpp

磁盘调度算法

/*
*		磁盘调度算法
*
*	
*
*		2007.1.2
*/

#include <math.h>
#include <time.h>
#include <stdlib.h>
#include <iomanip.h>
#include <iostream.h>

#define NUM	100

/****自定义的结构体****/
typedef struct
{
	int m_value;
	int m_state;
}myArray;

/*
*		自定义结构体的初始化函数
*/
void Initialize(myArray c[], int &l)
{
ER1:cout<< endl << " 请输入要访问的磁道数目:  ";
	cin>> l;
	if ((l < 1) || (l > 100))
	{
		cout<< endl << " 您输入的有误, 请重新输入. " << endl;
		goto ER1;
	}
	for (int i=0; i<l; i++)
	{
		cout<< endl << " 请输入第 " << i+1 << " 个要访问的磁道号:  ";
		cin>> c[i].m_value;
		c[i].m_state = 0;
	}
}

/*
*		Fcfs算法的创建函数
*/
void Fcfs(myArray c[], int l, float &result)
{
	int begin, temp[NUM]={0}; 
	float average=0.0;
	cout<< endl << " 请输入开始时的磁道号:  ";
	cin>> begin;
	cout<< endl;
	for (int i=0; i<l; i++)
	{
		temp[i] = abs(c[i].m_value - begin);
		begin = c[i].m_value;
		cout<< " 被访问的下一个磁道号 " << setw(3) << c[i].m_value << "  移动的距离 " << temp[i] << endl;
		average += temp[i];
	}
	average /= l;
	result = average;
	cout<< endl << " 平均寻道长度: " << average << endl;
}

/*
*		Sstf算法用到的排序函数
*/
void Sort(myArray c[], int begin, int l, int &now)
{
	int temp, k, h=0, assisant[NUM]={0};
	for (int i=0; i<l; i++)
	{
		if (c[i].m_state == 0)
		{
			assisant[h] = abs(c[i].m_value - begin);
			h++;
		}
	}
	for (i=0; i<h-1; i++)
	{	
		k = i;
		for (int j=i+1; j<h; j++)
		{
			if (assisant[k] < assisant[j])
			{
				k = j;
			}
			if (assisant[i] != assisant[k])
			{
				temp = assisant[i];
				assisant[i] = assisant[k];
				assisant[k] = temp;
			}
		}
	}
	for (i=0; i<l; i++)
	{
		if (assisant[h-1] == abs(c[i].m_value - begin))
		{
			now = c[i].m_value;
			c[i].m_state = 1;
		}
	}
}

/*
*		Sstf算法的创建函数
*/
void Sstf(myArray c[], int l, float &result)
{
	int begin, now, temp[NUM]={0}; 
	float average=0.0;
	cout<< endl << " 请输入开始时的磁道号:  ";
	cin>> begin;
	cout<< endl;
	for (int i=0; i<l; i++)
	{
		Sort(c, begin, l, now);
		temp[i] = abs(now - begin);
		begin = now;
		cout<< " 被访问的下一个磁道号 " << setw(3) << now << "  移动的距离 " << temp[i] << endl;
		average += temp[i];
	}
	average /= l;
	result = average;
	cout<< endl << " 平均寻道长度: " << average << endl;
}

/*
*		Scan算法用到的变换方向的函数
*/
void MyDirection(myArray c[], int l, int &begin, float &average)
{
	int now, temp[NUM]={0};
	for (int i=0; i<l; i++)
	{
		Sort(c, begin, l, now);
		temp[i] = abs(now - begin);
		begin = now;
		cout<< " 被访问的下一个磁道号 " << setw(3) << now << "  移动的距离 " << temp[i] << endl;
		average += temp[i];
	}
}

/*
*		Scan算法用到的辅助结构体初始化函数
*/
void MyInitialize(myArray c[], int l)
{
	for (int i=0; i<l; i++)
	{
		c[i].m_state = 0;
		c[i].m_value = 0;
	}
}

/*
*		Scan算法的创建函数
*/
void Scan(myArray c[], int l, float &result)
{
	int begin, direction, p=0, q=0;
	float average=0.0;	
	myArray max[NUM], min[NUM];
	MyInitialize(max, l);
	MyInitialize(min, l);
	cout<< endl << " 请输入开始时的磁道号:  ";
	cin>> begin;
ER3:cout<< endl << " 从磁道增加方向开始请按 1, 从磁道递减方向开始请按 2:  ";
	cin>> direction;
	if ((direction < 1) || (direction > 2))
	{
		cout<< endl << " 您输入的有误, 请重新输入. " << endl;
		goto ER3;	
	}
	cout<< endl;
	for (int i=0; i<l; i++)
	{
		if (c[i].m_value >= begin)
		{
			max[p].m_value = c[i].m_value;
			p++;
		}
		else
		{
			min[q].m_value = c[i].m_value;
			q++;
		}
	}
	if (direction == 1)
	{
		MyDirection(max, p, begin, average);
		MyDirection(min, q, begin, average);
	}
	else
	{
		MyDirection(min, q, begin, average);
		MyDirection(max, p, begin, average);
	}
	average /= l;
	result = average;
	cout<< endl << " 平均寻道长度: " << average << endl;	
}

/*
*		Cscan算法用到的Fcfs函数
*/
void MyFcfs(myArray c[], int l, int begin, float &average)
{
	int k, temper, temp[NUM]={0}, assisant[NUM]={0};
	for (int i=0; i<l; i++)
	{
		assisant[i] = c[i].m_value;
	}	
	for (i=0; i<l-1; i++)
	{	
		k = i;
		for (int j=i+1; j<l; j++)
		{
			if (assisant[k] > assisant[j])
			{
				k = j;
			}
			if (assisant[i] != assisant[k])
			{
				temper = assisant[i];
				assisant[i] = assisant[k];
				assisant[k] = temper;
			}
		}
	}
	for (i=0; i<l; i++)
	{
		temp[i] = abs(assisant[i] - begin);
		begin = assisant[i];
		cout<< " 被访问的下一个磁道号 " << setw(3) << assisant[i] << "  移动的距离 " << temp[i] << endl;
		average += temp[i];
	}
}

/*
*		Cscan算法的创建函数
*/
void Cscan(myArray c[], int l, float &result)
{
	int begin, p=0, q=0;
	float average=0.0;	
	myArray max[NUM], min[NUM];
	MyInitialize(max, l);
	MyInitialize(min, l);
	cout<< endl << " 请输入开始时的磁道号:  ";
	cin>> begin;
	cout<< endl;
	for (int i=0; i<l; i++)
	{
		if (c[i].m_value >= begin)
		{
			max[p].m_value = c[i].m_value;
			p++;
		}
		else
		{
			min[q].m_value = c[i].m_value;
			q++;
		}
	}
	MyDirection(max, p, begin, average);
	MyFcfs(min, q, begin, average);
	average /= l;
	result = average;
	cout<< endl << " 平均寻道长度: " << average << endl;	
}

/*
*		随机例子的创建函数
*/
void MySimple(myArray c[])
{
	int length, choice;
	float sum;
	srand(time(NULL));
	length = rand() % 30 + 10;
	for (int i=0; i<length; i++)
	{
		c[i].m_state = 0;
		c[i].m_value = rand() % 150 + 1;
	}
	cout<< endl << " 随机选取了磁道总数为:  " << length << endl;
	choice = rand() % 4 + 1;
	switch (choice)
	{
		case	1:		cout<< endl << " 本例采用Fcfs算法. " << endl;
						Fcfs(c, length, sum);
						break;
		case    2:		cout<< endl << " 本例采用Sstf算法. " << endl;
						Sstf(c, length, sum);
						break;
		case    3:		cout<< endl << " 本例采用Scan算法. " << endl;
						Scan(c, length, sum);
						break;
		case	4:		cout<< endl << " 本例采用Cscan算法. " << endl;
						Cscan(c, length, sum);
						break;	
	}
}

/*
*		磁盘调度算法的主函数	
*/
int main()
{
	cout<< " 磁盘调度算法. " << endl;

	int length, choice, go, simple;
	float sum[4]={0};
	myArray container[NUM];
TO:	cout<< endl << " 想看一个随机例子请按1, 想自己创建一个例子请按其他键.  ";
	cin>> simple;
	if (simple == 1)
	{
		MySimple(container);
	}
	else
	{
		Initialize(container, length);

		cout<< endl << " 磁盘调度系列算法. " << endl;
		cout<< endl << "    1 FCFS算法. "<< endl;
		cout<< endl << "    2 SSTF算法. "<< endl;
		cout<< endl << "    3 SCAN算法. "<< endl;
		cout<< endl << "    4 CSCAN算法. " << endl;	
ER2:	cout<< endl << " 请选择: ";
		cin>> choice;
		switch (choice)
		{
			case	1:		Fcfs(container, length, sum[0]);
							break;
			case    2:		Sstf(container, length, sum[1]);
							break;
			case    3:		Scan(container, length, sum[2]);
							break;
			case	4:		Cscan(container, length, sum[3]);
							break;	
			default  :		cout<< endl << " 您输入的有误, 请重新输入. " << endl;
							goto ER2;
		}
	}
	cout<< endl << " 想继续看别的算法请按1, 否则请按其他键:  ";
	cin>> go;
	if (go == 1)
	{
		goto TO;
	}
	return 0;
}