int
main(int argc, char **argv)
{
int enabled;
thread_init();
/* show interrupt handler output */
register_interrupt_handler(1);
test(1);
/* test interrupts_on/off/set */
enabled = interrupts_off();
assert(enabled);
test(0);
enabled = interrupts_off();
assert(!enabled);
test(0);
enabled = interrupts_set(1);
assert(!enabled);
test(1);
enabled = interrupts_set(1);
assert(enabled);
test(1);
exit(0);
}
static void
test_wakeup_thread(int num)
{
int i;
int ret;
struct timeval start, end, diff;
for (i = 0; i < LOOPS; i++) {
int enabled;
gettimeofday(&start, NULL);
/* track the number of sleeping threads with interrupts
* disabled to avoid wakeup races. */
enabled = interrupts_off();
assert(enabled);
__sync_fetch_and_add(&nr_sleeping, 1);
ret = thread_sleep(queue);
assert(thread_ret_ok(ret));
interrupts_set(enabled);
gettimeofday(&end, NULL);
timersub(&end, &start, &diff);
/* thread_sleep should wait at least 4-5 ms */
if (diff.tv_sec == 0 && diff.tv_usec < 4000) {
unintr_printf("%s took %ld us. That's too fast."
" You must be busy looping\n",
__FUNCTION__, diff.tv_usec);
goto out;
}
}
out:
__sync_fetch_and_add(&done, 1);
}
static void
show_interrupt(void)
{
int err;
/* QUESTION: how did we get here if there was an assert above? */
/* now think about interrupts. you will need to understand how they
* work, and how they interact with get/setcontext for implementing
* preemptive threading. */
/* QUESTION: what does interrupts_on() do? see interrupt.c */
interrupts_on();
/* getcontext stores the process's signal mask */
err = getcontext(&mycontext);
assert(!err);
/* QUESTION: Are interrupts masked (i.e., disabled) in mycontext?
* HINT: use sigismember below. */
printf("interrupt is disabled = %d\n",
(unsigned int) sigismember(&mycontext.uc_sigmask, SIG_TYPE));
interrupts_off();
err = getcontext(&mycontext);
assert(!err);
/* QUESTION: which fields of mycontext changed as a result of the
* getcontext call above? */
printf("interrupt is disabled = %d\n",
(unsigned int) sigismember(&mycontext.uc_sigmask, SIG_TYPE));
}
/* turn off interrupts while printing */
int
unintr_printf(const char *fmt, ...)
{
int ret, enabled;
va_list args;
enabled = interrupts_off();
va_start(args, fmt);
ret = vprintf(fmt, args);
va_end(args);
interrupts_set(enabled);
return ret;
}
