磁盘调度算法c语言

磁盘调度算法是操作系统中的重要算法之一，主要用于优化磁盘访问的效率。下面是一个简单的磁盘调度算法的C语言实现：

#include <stdio.h>
#include <stdlib.h>

#define MAX_REQUESTS 100

// 存储磁盘请求的队列
int requests[MAX_REQUESTS];

// 记录磁头当前所在的位置
int head_position = 50;

// 记录磁盘上最大的块号
int max_block = 199;

// 记录磁盘上最小的块号
int min_block = 0;

// 记录磁盘移动的总距离
int total_distance = 0;

// 计算磁盘移动的距离
int calculate_distance(int current_position, int next_position) {
    return abs(current_position - next_position);
}

// 根据先来先服务算法调度磁盘请求
void fcfs() {
    int i;
    for (i = 0; i < MAX_REQUESTS; i++) {
        int next_position = requests[i];
        total_distance += calculate_distance(head_position, next_position);
        head_position = next_position;
    }
}

// 根据扫描算法调度磁盘请求
void scan() {
    int i, j;
    for (i = 0; i < MAX_REQUESTS; i++) {
        for (j = i + 1; j < MAX_REQUESTS; j++) {
            if (requests[i] > requests[j]) {
                int temp = requests[i];
                requests[i] = requests[j];
                requests[j] = temp;
            }
        }
    }

    int i, j;
    for (i = 0; i < MAX_REQUESTS; i++) {
        if (requests[i] >= head_position) {
            for (j = i; j < MAX_REQUESTS; j++) {
                total_distance += calculate_distance(head_position, requests[j]);
                head_position = requests[j];
            }

            for (j = i - 1; j >= 0; j--) {
                total_distance += calculate_distance(head_position, requests[j]);
                head_position = requests[j];
            }

            break;
        }
    }
}

int main() {
    int i;
    for (i = 0; i < MAX_REQUESTS; i++) {
        requests[i] = rand() % (max_block - min_block + 1) + min_block;
    }

    fcfs();
    printf("Total distance with FCFS algorithm: %d\n", total_distance);

    total_distance = 0;
    scan();
    printf("Total distance with SCAN algorithm: %d\n", total_distance);

    return 0;
}

上面的代码实现了两种不同的磁盘调度算法：先来先服务算法和扫描算法。在主函数中，我们随机生成了100个磁盘请求，并用这两种算法来调度这些请求并计算出磁盘移动的总距离。