csma/cd协议用 C++实现一下

CSMA/CD协议是一种用于以太网的竞争多路访问协议，下面是一个简单的C++实现：

#include <iostream>
#include <cstdlib>
#include <ctime>

using namespace std;

const int MAX_ATTEMPTS = 16;  // 最大尝试次数
const int SLOT_TIME = 1;     // 每个时间槽的时间（单位：秒）
const int COLLISION_TIME = 2; // 冲突检测时间（单位：秒）
const int BACKOFF_RANGE = 1024; // 后退时间的范围

// 模拟发送数据帧的函数
void send_frame(int station_id, bool channel_busy) {
    if (!channel_busy) {
        cout << "Station " << station_id << " sending frame..." << endl;
        // 发送数据帧的过程
    } else {
        cout << "Station " << station_id << " channel busy, waiting..." << endl;
    }
}

// 模拟后退的函数
void backoff(int &backoff_time) {
    int random_time = rand() % BACKOFF_RANGE; // 随机生成一个后退时间
    backoff_time = random_time * SLOT_TIME;
    cout << "Backing off for " << backoff_time << " seconds..." << endl;
}

int main() {
    srand(time(NULL)); // 初始化随机数生成器

    bool channel_busy = false; // 信道是否繁忙
    int attempts = 0; // 尝试次数
    int backoff_time = 0; // 后退时间

    // 模拟多个站点发送数据帧的过程
    for (int i = 1; i <= 5; i++) {
        cout << "Station " << i << " wants to send a frame." << endl;
        while (attempts < MAX_ATTEMPTS) {
            if (!channel_busy) {
                send_frame(i, channel_busy);
                channel_busy = true;
                backoff_time = 0;
                break;
            } else {
                backoff(backoff_time);
                channel_busy = true;
                attempts++;
                if (attempts == MAX_ATTEMPTS) {
                    cout << "Station " << i << " failed to send frame after " << attempts << " attempts." << endl;
                    break;
                }
                cout << "Station " << i << " waiting for " << backoff_time << " seconds..." << endl;
                for (int j = 0; j < backoff_time; j++) {
                    sleep(SLOT_TIME); // 等待一个时间槽
                    if (!channel_busy) {
                        break;
                    }
                }
            }
        }
        channel_busy = false;
        attempts = 0;
    }

    return 0;
}

这个程序模拟了5个站点发送数据帧的过程，每个时间槽的时间为1秒，最大尝试次数为16次，后退时间的范围为0到1023个时间槽。在每一个时间槽内，如果信道空闲，一个站点就会发送数据帧，否则就会等待一段随机的后退时间后再次尝试发送。如果尝试次数超过了最大尝试次数，就认为发送失败。