Replace notifier::lock_shared() with try_lock_shared()

Also add notify_one(), try_lock() and unlock()
Move some code in cond.cpp

Utilities/cond.cpp

@@ -120,3 +120,97 @@ void cond_variable::imp_wake(u32 _count) noexcept
 	}
 #endif
 }
+
+bool notifier::imp_try_lock(u32 count)
+{
+	return m_counter.atomic_op([&](u32& value)
+	{
+		if ((value % (max_readers + 1)) + count <= max_readers)
+		{
+			value += count;
+			return true;
+		}
+
+		return false;
+	});
+}
+
+void notifier::imp_unlock(u32 count)
+{
+	const u32 counter = m_counter.sub_fetch(count);
+
+	if (UNLIKELY(counter % (max_readers + 1)))
+	{
+		return;
+	}
+
+	if (counter)
+	{
+		const u32 _old = m_counter.atomic_op([](u32& value) -> u32
+		{
+			if (value % (max_readers + 1))
+			{
+				return 0;
+			}
+
+			return std::exchange(value, 0) / (max_readers + 1);
+		});
+
+		const u32 wc = m_cond.m_value;
+
+		if (_old && wc)
+		{
+			m_cond.imp_wake(_old > wc ? wc : _old);
+		}
+	}
+}
+
+u32 notifier::imp_notify(u32 count)
+{
+	return m_counter.atomic_op([&](u32& value) -> u32
+	{
+		if (const u32 add = value % (max_readers + 1))
+		{
+			// Mutex is locked
+			const u32 result = add > count ? count : add;
+			value += result * (max_readers + 1);
+			return result;
+		}
+		else
+		{
+			// Mutex is unlocked
+			value = 0;
+			return count;
+		}
+	});
+}
+
+explicit_bool_t notifier::wait(u64 usec_timeout)
+{
+	const u32 _old = m_cond.m_value.fetch_add(1);
+
+	if (max_readers < m_counter.fetch_op([](u32& value)
+	{
+		if (value > max_readers)
+		{
+			value -= max_readers;
+		}
+
+		value -= 1;
+	}))
+	{
+		// Return without waiting
+		m_cond.imp_wait(_old, 0);
+		return true;
+	}
+
+	const bool res = m_cond.imp_wait(_old, usec_timeout);
+
+	while (!try_lock_shared())
+	{
+		// TODO
+		busy_wait();
+	}
+
+	return res;
+}