【操作系统】C语言模拟操作系统实现动态分区分配算法

#define _CRT_SECURE_NO_WARNINGS 1 
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<math.h>
#define N 10000
int n1;//空闲分区的个数
int n2;//作业区的个数
struct kongxian
{
	int start;  //起址
	int end;    //结束
	int length;  //长度
}kongxian[N];
struct zuoye
{
	int start;  //起址
	int end;   //结束
	int length;  //长度
}zuoye[N];
int cmp1(const void *a, const void *b)
{
	return (*(struct kongxian *)a).start - (*(struct kongxian *)b).start;
}
int cmp2(const void *a, const void *b)
{
	return (*(struct zuoye *)a).start - (*(struct zuoye *)b).start;
}
void init()
{
	n1 = 1;  //初始时只有一个空闲区
	n2 = 0;  //初始没有作业
	kongxian[0].start = 0;
	kongxian[0].end = 511;
	kongxian[0].length = 512;
}
void print1() //打印空闲分区
{
	int i;
	for (i = 0; i<n1; i++)
		printf("空闲分区ID:%d 起止:%d 结束:%d 长度:%d\n", i, kongxian[i].start, kongxian[i].end, kongxian[i].length);
}
void print2() //打印作业分区
{
	int i;
	for (i = 0; i<n2; i++)
		printf("作业分区ID：%d 起止:%d 结束:%d 长度:%d\n", i, zuoye[i].start, zuoye[i].end, zuoye[i].length);
}
int main()
{
	int i, j, t, len, flag, id;
	int front, middle, behind;
	int t1, t2;
	init();
	print1();
	printf("输入1装入新作业，输入0回收作业，输入-1结束\n");
	while (scanf("%d", &t) != EOF)
	{
		if (t == 1)  //装入新作业
		{
			printf("请输入作业的占用空间的长度 ");
			scanf("%d", &len);
			flag = 0;
			for (i = 0; i<n1; i++)
			{
				if (kongxian[i].length >= len)  //首次适应算法
				{
					flag = 1;
					break;
				}
			}
			if (!flag)
			{
				printf("内存分配失败\n");
			}
			else
			{
				//将该作业加入作业区里
				zuoye[n2].start = kongxian[i].start;
				zuoye[n2].end = zuoye[n2].start + len;
				zuoye[n2].length = len;
				n2++;  //作业数加1
				if (kongxian[i].length == len) //该分区全部用于分配，删除该空闲分区
				{
					for (j = i; j<n1 - 1; j++)
					{
						kongxian[j].start = kongxian[j + 1].start;
						kongxian[j].end = kongxian[j + 1].end;
						kongxian[j].length = kongxian[j + 1].length;
					}
					n1--;
				}
				else  //该空闲分区部分用于分配，剩余的留在空闲分区中
				{
					kongxian[i].start += len;
					kongxian[i].length -= len;
				}
			}
		}
		else if (t == 0)
		{
			printf("输入要回收的作业ID ");
			scanf("%d", &id);
			front = middle = behind = 0;
			for (i = 0; i<n1; i++)
			{
				if (kongxian[i].start>zuoye[id].end)
					break;
				if (kongxian[i].end == zuoye[id].start)  //待回收的作业上面有空闲分区
				{
					front = 1;
					t1 = i;
				}
				if (kongxian[i].start == zuoye[id].end)  //待回收的作业下面有空闲分区
				{
					behind = 1;
					t2 = i;
				}
			}
			if (!front&&!behind)  //待回收的作业上下均没有空闲分区
			{
				kongxian[n1].start = zuoye[id].start;
				kongxian[n1].end = zuoye[id].end;
				kongxian[n1].length = zuoye[id].length;
				n1++;  //空闲分区增加一个
				qsort(kongxian, n1, sizeof(struct kongxian), cmp1); //插入空闲分区后排序
				for (j = id; j<n2 - 1; j++)  //在作业分区中删除该作业
				{
					zuoye[j].start = zuoye[j + 1].start;
					zuoye[j].end = zuoye[j + 1].end;
					zuoye[j].length = zuoye[j + 1].length;
				}
				n2--;
			}
			if (front &&behind)  //待回收的作业上下均有空闲分区
				middle = 1;
			if (front&&!middle)  //合并待回收的作业和上面的空闲分区
			{
				kongxian[t1].end += zuoye[id].length;
				kongxian[t1].length += zuoye[id].length;
				for (j = id; j<n2 - 1; j++)  //在作业分区中删除该作业
				{
					zuoye[j].start = zuoye[j + 1].start;
					zuoye[j].end = zuoye[j + 1].end;
					zuoye[j].length = zuoye[j + 1].length;
				}
				n2--;
			}
			if (middle)  //合并待回收的作业和上下的空闲分区
			{
				kongxian[t1].end = kongxian[t2].end;
				kongxian[t1].length += (zuoye[id].length + kongxian[t2].length);
				//删除空闲分区t2
				for (j = t2; j<n1 - 1; j++)
				{
					kongxian[j].start = kongxian[j + 1].start;
					kongxian[j].end = kongxian[j + 1].end;
					kongxian[j].length = kongxian[j + 1].length;
				}
				n1--;
				for (j = id; j<n2 - 1; j++)  //在作业分区中删除该作业
				{
					zuoye[j].start = zuoye[j + 1].start;
					zuoye[j].end = zuoye[j + 1].end;
					zuoye[j].length = zuoye[j + 1].length;
				}
				n2--;
			}
			if (behind &&!middle) //合并待回收的作业和下面的分区
			{
				kongxian[t2].start -= zuoye[id].length;
				kongxian[t2].length += zuoye[id].length;
				for (j = id; j<n2 - 1; j++)  //在作业分区中删除该作业
				{
					zuoye[j].start = zuoye[j + 1].start;
					zuoye[j].end = zuoye[j + 1].end;
					zuoye[j].length = zuoye[j + 1].length;
				}
				n2--;
			}
		}
		else
		{
			printf("操作结束\n");
			break;
		}
		print1();
		print2();
	}
	return 0;
}