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/*
* main.cpp
*
* Created on: 31.10.2010
* Author: sven
*/
#include <pthread.h>
#include <semaphore.h>
#include <time.h>
#include <sys/time.h>
#include <signal.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
// debug printing
#ifdef DEBUG_MODE
#include <stdio.h>
#define DEBUG_PRINT(format, args...)\
{\
static char message[512];\
snprintf(message,512,format, ##args);\
fprintf(stdout, "[%s: %d] : %s\n", __PRETTY_FUNCTION__,__LINE__, message);\
fflush(stdout);\
}
#else
#define DEBUG_PRINT(format, args...)
#endif // DEBUG_MODE
/*
* global variables
*/
sem_t main_block,timer_block;
pthread_t timer_thread;
bool stop_timer_thread = false;
pthread_mutex_t stop_mutex = PTHREAD_MUTEX_INITIALIZER;
// 0 sec
const long TIMER_INTERVAL_SECS = 0;
// 10 msec
const long TIMER_INTERVAL_USECS = 10000;
struct sigaction timer_action, quit_action;
/*
* function prototypes
*/
void readSensors();
void initializeClock();
void initializeMain();
void WaitForNextCycle();
void ActuateProcess();
bool CalculateNewSetValues();
void Error();
void* TimerThreadProc(void*);
void timer_handler(int);
void* TimerThreadProc(void*) {
/**
* Timer code originally from
* http://www.informit.com/articles/article.aspx?p=23618&seqNum=14
*/
DEBUG_PRINT("entry Process: %d Thread: %lu",(int)getpid(),pthread_self());
bool stop_me = false;
struct itimerval timer;
/* Install timer_handler as the signal handler for SIGALRM. */
timer_action.sa_handler = timer_handler;
sigemptyset(&timer_action.sa_mask);
timer_action.sa_flags = 0;
sigaction(SIGALRM,&timer_action,NULL);
/* Configure the timer to expire after
* TIMER_INTERVAL_SECS + TIMER_INTERVAL_USECS... */
timer.it_value.tv_sec = TIMER_INTERVAL_SECS;
timer.it_value.tv_usec = TIMER_INTERVAL_USECS;
/* ... and every TIMER_INTERVAL_SECS+TIMER_INTERVAL_USECS after that. */
timer.it_interval.tv_sec = TIMER_INTERVAL_SECS;
timer.it_interval.tv_usec = TIMER_INTERVAL_USECS;
/* If the timer code is ITIMER_REAL,
* the process is sent a SIGALRM signal after the
* specified wall-clock time has elapsed*/
setitimer (ITIMER_REAL, &timer, NULL);
while(1) {
pthread_mutex_lock(&stop_mutex);
stop_me = stop_timer_thread;
pthread_mutex_unlock(&stop_mutex);
if(stop_me) {
DEBUG_PRINT("exiting thread Process: %d Thread: %lu",(int)getpid(),pthread_self());
pthread_exit(NULL);
}
DEBUG_PRINT("waiting for timer_handler Process: %d Thread: %lu",(int)getpid(),pthread_self());
sem_wait(&timer_block);
DEBUG_PRINT("waking up main Process: %d Thread: %lu",(int)getpid(),pthread_self());
sem_post(&main_block);
}
DEBUG_PRINT("should never happen Process: %d Thread: %lu",(int)getpid(),pthread_self());
return NULL;
}
void timer_handler(int signum) {
DEBUG_PRINT("entry Process: %d Thread: %lu",(int)getpid(),pthread_self());
static int count = 0;
DEBUG_PRINT("timer expired %d times", ++count);
sem_post(&timer_block);
DEBUG_PRINT("exit");
}
void quit_handler(int signum) {
DEBUG_PRINT("entry Process: %d Thread: %lu",(int)getpid(),pthread_self());
int semval;
pthread_mutex_lock(&stop_mutex);
stop_timer_thread = true;
pthread_mutex_unlock(&stop_mutex);
sem_getvalue(&timer_block,&semval);
if(semval > 0) {
DEBUG_PRINT("waking up timer thread");
sem_post(&timer_block);
}
pthread_join(timer_thread,NULL);
DEBUG_PRINT("Joined timer thread");
//clean up
sem_destroy(&timer_block);
sem_destroy(&main_block);
pthread_mutex_destroy(&stop_mutex);
DEBUG_PRINT("exit");
exit(EXIT_SUCCESS);
}
void WaitForNextCycle() {
DEBUG_PRINT("entry Process: %d Thread: %lu",(int)getpid(),pthread_self());
sem_wait(&main_block);
DEBUG_PRINT("exit");
}
void readSensors() {
DEBUG_PRINT("entry Process: %d Thread: %lu",(int)getpid(),pthread_self());
struct timeval tv;
struct timezone tz;
struct tm *tm;
gettimeofday(&tv, &tz);
tm=localtime(&tv.tv_sec);
printf(" %d:%02d:%02d %lu \n", tm->tm_hour, tm->tm_min,
tm->tm_sec, tv.tv_usec);
DEBUG_PRINT("exit");
}
void Error() {
DEBUG_PRINT("entry Process: %d Thread: %lu",(int)getpid(),pthread_self());
DEBUG_PRINT("exit");
}
bool CalculateNewSetValues() {
DEBUG_PRINT("entry Process: %d Thread: %lu",(int)getpid(),pthread_self());
DEBUG_PRINT("exit");
return true;
}
void ActuateProcess() {
DEBUG_PRINT("entry Process: %d Thread: %lu",(int)getpid(),pthread_self());
DEBUG_PRINT("exit");
}
void initializeClock()
{
DEBUG_PRINT("entry Process: %d Thread: %lu",(int)getpid(),pthread_self());
pthread_create(&timer_thread,NULL,TimerThreadProc,NULL);
DEBUG_PRINT("exit");
}
void initializeMain() {
DEBUG_PRINT("entry Process: %d Thread: %lu",(int)getpid(),pthread_self());
/* init semaphore as closed */
sem_init(&main_block,0,0);
sem_init(&timer_block,0,0);
/* catch all interesting signals */
quit_action.sa_handler = quit_handler;
sigemptyset(&quit_action.sa_mask);
quit_action.sa_flags = 0;
sigaction(SIGTERM,&quit_action,NULL);
sigaction(SIGQUIT,&quit_action,NULL);
sigaction(SIGINT,&quit_action,NULL);
sigaction(SIGHUP,&quit_action,NULL);
DEBUG_PRINT("exit");
}
int main(int argc, char* argv[])
{
initializeMain();
initializeClock();
while(1) {
readSensors();
if(CalculateNewSetValues())
ActuateProcess();
else
Error();
WaitForNextCycle();
}
return EXIT_SUCCESS;
}
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