[fibers] Query condition before and after yield

src/modm/processing/fiber/functions.hpp

@@ -79,6 +79,8 @@ requires requires { std::is_invocable_r_v<bool, Function, void>; }
 bool
 poll_for(std::chrono::duration<Rep, Period> sleep_duration, Function &&condition)
 {
+	if (std::forward<Function>(condition)()) return true;
+
 	// Only choose the microsecond clock if necessary
 	using Clock = std::conditional_t<
 		std::is_convertible_v<std::chrono::duration<Rep, Period>,
@@ -91,8 +93,8 @@ poll_for(std::chrono::duration<Rep, Period> sleep_duration, Function &&condition
 
 	const auto start = Clock::now();
 	do {
-		if (std::forward<Function>(condition)()) return true;
 		modm::this_fiber::yield();
+		if (std::forward<Function>(condition)()) return true;
 	}
 	while((Clock::now() - start) <= clock_sleep_duration);
 	return false;
@@ -114,11 +116,13 @@ requires requires { std::is_invocable_r_v<bool, Function, void>; }
 bool
 poll_until(std::chrono::time_point<Clock, Duration> sleep_time, Function &&condition)
 {
+	if (std::forward<Function>(condition)()) return true;
+
 	const auto start = Clock::now();
 	const auto sleep_duration = sleep_time - start;
 	do {
-		if (std::forward<Function>(condition)()) return true;
 		modm::this_fiber::yield();
+		if (std::forward<Function>(condition)()) return true;
 	}
 	while((Clock::now() - start) <= sleep_duration);
 	return false;