/* * CSMA/CD simulator * Author: Gong Han */ #include <pthread.h>#include <stdio.h>#include <time.h>#include <string.h>#include <stdbool.h>#include <math.h>#include <stdlib.h> #define MAX 16 typedef struct { int id; //host蔔id int time; //縣?駭?祠? int total; //?疇?挪 unsigned long time_length; //2%tau??} host_struct; pthread_t thread[MAX];host_struct hs[MAX]; pthread_mutex_t mut;//鐫濕?bool bus = false; bool detect_and_set() { pthread_mutex_lock(&mut); if (!bus) { bus = true; pthread_mutex_unlock(&mut); return true; } else { pthread_mutex_unlock(&mut); return false; }} void *host(void *arg) { bool flag; host_struct *phs = (host_struct *) arg; //輜証???蔔??hs int i; unsigned long sleep_time; for (i = 0; i < phs->total; i++) { flag = false; while (phs->time < 16 && !flag) { sleep_time = (unsigned long) ((pow(2, (phs->time < 10 ? phs->time : 10)) - 1) * phs->time_length); usleep(sleep_time); if (detect_and_set()) { srand((int) time(0)); usleep((unsigned long) (4000 + 1000.0 * rand() / (RAND_MAX + 1.0))); flag = true; bus = false; printf("Host:%d Packet:%d Times:%d Succeed\n", phs->id, i, phs->time); } else { (phs->time)++; printf("Host:%d Packet:%d Times:%d Collision Detected.\n", phs->id, i, phs->time); } if (phs->time >= 16) { printf("Host:%d Packet:%d Times:%d Dropped.\n", phs->id, i, phs->time); } } phs->time = 0; } return (void *)0;} void thread_create(void) { int i; memset(&thread, 0, sizeof (thread)); /* 鏝偎蔔??嗨漬?Debug蔔▏??槽度岌價槽鄧?、 */ for (i = 0; i < MAX; i++) { hs[i].id = i; hs[i].time = 0; hs[i].time_length = 5000; hs[i].total = 5; } for (i = 0; i < MAX; i++) { /*?佳?頫*/ if (pthread_create(&thread[i], NULL, host, (void *) & hs[i]) != 0) exit(1); }} void thread_wait2end(void) { /*娟迭?頫?菩*/ int i; for (i = 0; i < MAX; i++) { if (thread[i] != 0) { pthread_join(thread[i], NULL); } }} int main() { pthread_mutex_init(&mut, NULL); thread_create(); thread_wait2end(); return 0;}
