磁盘调度算法（FIFO、SSTF、SCAN、C-SCAN）代码

以下是磁盘调度算法的代码实现（使用 Python 语言）：

1. 先来先服务（FIFO）算法

def disk_scheduling_FIFO(requests, start):
    total_head_movement = 0
    current = start

    for request in requests:
        total_head_movement += abs(request - current)
        current = request

    return total_head_movement

2. 最短寻道时间优先（SSTF）算法

def disk_scheduling_SSTF(requests, start):
    total_head_movement = 0
    current = start

    while requests:
        distances = [abs(request - current) for request in requests]
        min_distance_index = distances.index(min(distances))
        min_distance_request = requests.pop(min_distance_index)
        total_head_movement += abs(min_distance_request - current)
        current = min_distance_request

    return total_head_movement

3. 扫描（SCAN）算法

def disk_scheduling_SCAN(requests, start):
    total_head_movement = 0
    current = start
    direction = 'right'

    while requests:
        distances = [abs(request - current) for request in requests]

        if direction == 'right':
            right_distances = [distance for distance in distances if request - current >= 0]
            if right_distances:
                min_right_distance = min(right_distances)
                min_right_index = distances.index(min_right_distance)
                min_distance_request = requests.pop(min_right_index)
                total_head_movement += abs(min_distance_request - current)
                current = min_distance_request
            else:
                direction = 'left'
        else:
            left_distances = [distance for distance in distances if request - current < 0]
            if left_distances:
                min_left_distance = min(left_distances)
                min_left_index = distances.index(min_left_distance)
                min_distance_request = requests.pop(min_left_index)
                total_head_movement += abs(min_distance_request - current)
                current = min_distance_request
            else:
                direction = 'right'

    return total_head_movement

4. 循环扫描（C-SCAN）算法

def disk_scheduling_CSCAN(requests, start):
    total_head_movement = 0
    current = start

    while requests:
        distances = [abs(request - current) for request in requests]

        if current < max(requests):
            right_distances = [distance for distance in distances if request - current >= 0]
            if right_distances:
                min_right_distance = min(right_distances)
                min_right_index = distances.index(min_right_distance)
                min_distance_request = requests.pop(min_right_index)
                total_head_movement += abs(min_distance_request - current)
                current = min_distance_request
            else:
                total_head_movement += abs(max(requests) - current)
                current = max(requests)
        else:
            left_distances = [distance for distance in distances if request - current < 0]
            if left_distances:
                min_left_distance = min(left_distances)
                min_left_index = distances.index(min_left_distance)
                min_distance_request = requests.pop(min_left_index)
                total_head_movement += abs(min_distance_request - current)
                current = min_distance_request
            else:
                total_head_movement += abs(min(requests) - current)
                current = min(requests)

    return total_head_movement

以上代码仅仅是展示了磁盘调度算法的实现，实际应用时还需要考虑各种边界情况和异常处理。