ftsp算法C语言实现

FTSP (Flooding Time Synchronization Protocol) 是一种分布式的时间同步协议，适用于无线传感器网络中的节点之间进行时间同步。以下是 FTSP 算法的 C 语言实现： ```c #include <stdio.h> #include <stdlib.h> #include <string.h> #include <math.h> #include <time.h> // 定义 FTSP 协议中用到的常量 #define MAX_MSG 10 // 最大消息数 #define MAX_NEIGHBORS 10 // 最大邻居节点数 #define MESSAGE_HELLO 0 // HELLO 消息类型 #define MESSAGE_SYNC 1 // SYNC 消息类型 #define MESSAGE_SYNC_ACK 2 // SYNC_ACK 消息类型 #define ROOT_ID 0 // 根节点的 ID #define ROUND_DURATION 1 // 一轮时间的长度（单位为秒） #define MAX_ROUND_ERROR 0.1 // 最大轮间误差（单位为秒） // 定义消息的结构体 typedef struct _message { int src; // 源节点 ID int dest; // 目标节点 ID int type; // 消息类型 double timestamp; // 时间戳 } message_t; // 定义节点的结构体 typedef struct _node { int id; // 节点 ID int neighbors[MAX_NEIGHBORS]; // 邻居节点的 ID 列表 int num_neighbors; // 邻居节点数 double clock_offset; // 时钟偏差 double clock_skew; // 时钟漂移 double round_start_time; // 当前轮的起始时间 double round_time_offset; // 当前轮的时间偏移 double round_skew; // 当前轮的时钟漂移 } node_t; // 定义全局变量 int num_nodes; // 节点数 node_t *nodes; // 节点列表 message_t messages[MAX_MSG]; // 消息列表 int num_messages; // 消息数 int root_id = ROOT_ID; // 根节点 ID // 定义消息发送函数 void send_message(int src, int dest, int type, double timestamp) { if (num_messages < MAX_MSG) { messages[num_messages].src = src; messages[num_messages].dest = dest; messages[num_messages].type = type; messages[num_messages].timestamp = timestamp; num_messages++; } } // 定义消息处理函数 void process_message(int node_id, message_t *msg) { node_t *node = &nodes[node_id]; double timestamp = msg->timestamp; double time_diff = 0; double delay = 0; int i; switch (msg->type) { case MESSAGE_HELLO: // 处理 HELLO 消息 if (node_id != root_id) { send_message(node_id, root_id, MESSAGE_HELLO, timestamp); } break; case MESSAGE_SYNC: // 处理 SYNC 消息 delay = (double)(rand() % 1000) / 1000.0; // 模拟传输延迟 timestamp += delay; time_diff = timestamp - node->round_start_time; if (node_id == root_id) { // 如果是根节点，则直接回复 SYNC_ACK 消息 send_message(root_id, msg->src, MESSAGE_SYNC_ACK, timestamp); } else { // 如果不是根节点，则将 SYNC 消息转发给所有邻居节点 for (i = 0; i < node->num_neighbors; i++) { send_message(node_id, node->neighbors[i], MESSAGE_SYNC, timestamp); } // 更新时钟偏差和时钟漂移 node->clock_offset = (time_diff + msg->timestamp - node->round_start_time) / 2.0; node->clock_skew = (time_diff - node->clock_offset) / ROUND_DURATION; } break; case MESSAGE_SYNC_ACK: // 处理 SYNC_ACK 消息 delay = (double)(rand() % 1000) / 1000.0; // 模拟传输延迟 timestamp += delay; time_diff = timestamp - node->round_start_time; // 更新时钟偏差和时钟漂移 node->clock_offset = (time_diff + msg->timestamp - node->round_start_time) / 2.0; node->clock_skew = (time_diff - node->clock_offset) / ROUND_DURATION; break; default: break; } } // 定义主函数 int main(int argc, char **argv) { int i, j; double round_duration = ROUND_DURATION; double max_round_error = MAX_ROUND_ERROR; double round_start_time = 0; double round_time_offset = 0; double round_skew = 0; double current_time = 0; double next_round_time = 0; double next_hello_time = 0; double error = 0; int num_sync = 0; int num_sync_ack = 0; int root_sync = 0; // 初始化随机数生成器 srand(time(NULL)); // 读取节点数和邻接矩阵 scanf("%d", &num_nodes); nodes = (node_t*)malloc(num_nodes * sizeof(node_t)); for (i = 0; i < num_nodes; i++) { nodes[i].id = i; nodes[i].num_neighbors = 0; nodes[i].clock_offset = 0; nodes[i].clock_skew = 0; nodes[i].round_start_time = 0; nodes[i].round_time_offset = 0; nodes[i].round_skew = 0; for (j = 0; j < num_nodes; j++) { int is_neighbor; scanf("%d", &is_neighbor); if (is_neighbor) { nodes[i].neighbors[nodes[i].num_neighbors] = j; nodes[i].num_neighbors++; } } } // 发送初始 HELLO 消息 for (i = 0; i < num_nodes; i++) { send_message(i, root_id, MESSAGE_HELLO, 0); } // 开始时间同步 while (1) { // 发送 HELLO 消息 if (current_time >= next_hello_time) { for (i = 0; i < num_nodes; i++) { send_message(i, root_id, MESSAGE_HELLO, current_time); } next_hello_time = current_time + 1.0; } // 处理消息 for (i = 0; i < num_messages; i++) { message_t *msg = &messages[i]; if (msg->dest == root_id) { // 如果是根节点，则直接处理消息 process_message(msg->src, msg); } else { // 如果不是根节点，则将消息转发给目标节点 send_message(msg->src, msg->dest, msg->type, msg->timestamp); } } num_messages = 0; // 计算当前轮的时间偏移和时钟漂移 if (current_time >= next_round_time) { // 计算当前轮的起始时间 if (root_sync) { round_start_time = next_round_time - round_time_offset - round_skew * ROUND_DURATION; } else { round_start_time = next_round_time; } for (i = 0; i < num_nodes; i++) { node_t *node = &nodes[i]; if (node->id == root_id) { node->round_start_time = round_start_time; node->round_time_offset = round_time_offset; node->round_skew = round_skew; } else { node->round_start_time = round_start_time; node->round_time_offset = node->clock_offset + node->round_skew * ROUND_DURATION; node->round_skew = node->clock_skew; } } // 发送 SYNC 消息 for (i = 0; i < num_nodes; i++) { node_t *node = &nodes[i]; if (node->id == root_id) { // 如果是根节点，则等待所有节点回复 SYNC_ACK 消息 num_sync = 0; num_sync_ack = 0; for (j = 0; j < node->num_neighbors; j++) { send_message(root_id, node->neighbors[j], MESSAGE_SYNC, round_start_time); num_sync++; } root_sync = 1; } else { // 如果不是根节点，则发送 SYNC 消息并等待回复 SYNC_ACK 消息 send_message(node->id, root_id, MESSAGE_SYNC, round_start_time); num_sync++; } } // 等待 SYNC_ACK 消息 while (num_sync_ack < num_sync) { for (i = 0; i < num_messages; i++) { message_t *msg = &messages[i]; if (msg->type == MESSAGE_SYNC_ACK) { process_message(msg->dest, msg); num_sync_ack++; } } num_messages = 0; } // 计算时间偏移和时钟漂移的平均值 round_time_offset = 0; round_skew = 0; for (i = 0; i < num_nodes; i++) { node_t *node = &nodes[i]; if (node->id == root_id) { round_time_offset += node->round_time_offset; round_skew += node->round_skew; } else { round_time_offset += node->round_start_time - node->clock_offset; round_skew += node->clock_skew; } } round_time_offset /= (double)num_nodes; round_skew /= (double)num_nodes; // 检查轮间误差是否超过了最大值 error = round_start_time - next_round_time; if (error > max_round_error) { round_duration -= 0.1; } else if (error < -max_round_error) { round_duration += 0.1; } // 更新下一轮的起始时间 next_round_time += round_duration; root_sync = 0; } // 更新当前时间 current_time += 0.01; } return 0; } ``` 注意：以上代码仅供参考，实际使用时需要根据具体需求进行修改和优化。