Periodic thread terminated by pressing escape - c

Question

I wrote the following code to implement a periodic thread terminated when someone presses escape. The result is a periodic thread that continues also after i pressed escape.
Can you tell me where is the error please? The compiler compiles without any error and warning. Before reading the code jump to EDIT below.
#include <stdio.h>
#include <pthread.h>
#include <allegro.h>
#include <time.h>
void *task(void *p);
void time_add_ms(struct timespec *t, int ms);
int main()
{
int tret;
int a = 1;
allegro_init();
install_keyboard();
tret = pthread_create(&tid, NULL, task, (void*)&a);
pthread_join(tid, NULL);
printf("Thread1 returns %d\n", tret);
allegro_exit();
return 0;
}
/* Sommare quantità temporale espressa in ms al tempo nella struttura timespec */
void time_add_ms(struct timespec *t, int ms)
{
t->tv_sec += ms / 1000;
t->tv_nsec += (ms % 1000) * 1000000;
if (t->tv_nsec > 1000000000){
t->tv_nsec -= 1000000000;
t->tv_sec += 1;
}
}
/* Funzione da trasformare in task */
void *task(void *p)
{
struct timespec t;
int period = 100;
int *pi;
char scan = 0;
clock_gettime(CLOCK_MONOTONIC, &t);
time_add_ms(&t, period);
pi = (int *)p;
while (scan != KEY_ESC) {
if (keypressed()) scan = readkey() >> 8;
printf("This is TASK %d\n", *pi);
clock_nanosleep(CLOCK_MONOTONIC, TIMER_ABSTIME, &t, NULL);
time_add_ms(&t, period);
}
}
EDIT: maybe i found the problem, when i press escape, it prints the symbol ^, so the compiler or allegro doen't recognize the esc key.

Answer 1

This is not exactly finding the error, but I think it is what you want (more details here)
If you add following code to your main(), this will disable canonical mode, which will basically enable you to get characters immediately without waiting for a '\n' or EOF (or enter keypress in short) (already explained in the link above):
#include <termios.h>
#include <unistd.h>
int main(){
static struct termios oldt, newt;
tcgetattr( STDIN_FILENO, &oldt);
newt = oldt;
newt.c_lflag &= ~(ICANON);
tcsetattr( STDIN_FILENO, TCSANOW, &newt);
// rest of your code
}
And the thread loop here (I've changed it a little bit)
while (1) {
printf("This is TASK %d\n", *pi);
clock_nanosleep(CLOCK_MONOTONIC, TIMER_ABSTIME, &t, NULL);
time_add_ms(&t, period);
if(getchar()==27) break;
}