/* this is a very simple program meant to demonstrate a basic use of time, alarms and alarm-handling functions in eCos */ #include #include #define NTHREADS 1 #define STACKSIZE 4096 static cyg_handle_t thread[NTHREADS]; static cyg_thread thread_obj[NTHREADS]; static char stack[NTHREADS][STACKSIZE]; static void alarm_prog( cyg_addrword_t data ); /* we install our own startup routine which sets up threads and starts the scheduler */ void cyg_user_start(void) { cyg_thread_create(4, alarm_prog, (cyg_addrword_t) 0, "alarm_thread", (void *) stack[0], STACKSIZE, &thread[0], &thread_obj[0]); cyg_thread_resume(thread[0]); } /* we need to declare the alarm handling function (which is defined below), so that we can pass it to cyg_alarm_initialize() */ cyg_alarm_t test_alarm_func; /* alarm_prog() is a thread which sets up an alarm which is then handled by test_alarm_func() */ static void alarm_prog(cyg_addrword_t data) { cyg_handle_t test_counterH, system_clockH, test_alarmH; cyg_tick_count_t ticks; cyg_alarm test_alarm; unsigned how_many_alarms = 0, prev_alarms = 0, tmp_how_many; system_clockH = cyg_real_time_clock(); cyg_clock_to_counter(system_clockH, &test_counterH); cyg_alarm_create(test_counterH, test_alarm_func, (cyg_addrword_t) &how_many_alarms, &test_alarmH, &test_alarm); cyg_alarm_initialize(test_alarmH, cyg_current_time()+200, 200); /* get in a loop in which we read the current time and print it out, just to have something scrolling by */ for (;;) { ticks = cyg_current_time(); printf("Time is %llu\n", ticks); /* note that we must lock access to how_many_alarms, since the alarm handler might change it. this involves using the annoying temporary variable tmp_how_many so that I can keep the critical region short */ cyg_scheduler_lock(); tmp_how_many = how_many_alarms; cyg_scheduler_unlock(); if (prev_alarms != tmp_how_many) { printf(" ---> alarm calls so far: %u\n", tmp_how_many); prev_alarms = tmp_how_many; } cyg_thread_delay(30); } } /* test_alarm_func() is invoked as an alarm handler, so it should be quick and simple. in this case it increments the data that is passed to it. */ void test_alarm_func(cyg_handle_t alarmH, cyg_addrword_t data) { ++*((unsigned *) data); }