New shared_mutex

Experimental sync utils
New semaphore<>
New cond_variable
New owned_mutex

Utilities/sema.h

@@ -0,0 +1,110 @@
+#pragma once
+
+#include "types.h"
+#include "Atomic.h"
+
+// Lightweight semaphore helper class
+class semaphore_base
+{
+	// Semaphore value (shifted; negative values imply 0 with waiters, LSB is used to ping-pong signals between threads)
+	atomic_t<s32> m_value;
+
+	void imp_wait(bool lsb);
+
+	void imp_post(s32 _old);
+
+protected:
+	explicit constexpr semaphore_base(s32 value)
+		: m_value{value}
+	{
+	}
+
+	void wait()
+	{
+		// Unconditional decrement
+		if (UNLIKELY(m_value.sub_fetch(1 << 1) < 0))
+		{
+			imp_wait(false);
+		}
+	}
+
+	bool try_wait();
+
+	void post(s32 _max)
+	{
+		// Unconditional increment
+		const s32 value = m_value.fetch_add(1 << 1);
+
+		if (UNLIKELY(value < 0 || value >= _max))
+		{
+			imp_post(value & ~1);
+		}
+	}
+
+	bool try_post(s32 _max);
+
+public:
+	// Get current semaphore value
+	s32 get() const
+	{
+		// Load value
+		const s32 value = m_value;
+
+		// Return only positive value
+		return value < 0 ? 0 : value >> 1;
+	}
+};
+
+// Lightweight semaphore template (default arguments define binary semaphore and Def == Max)
+template <s32 Max = 1, s32 Def = Max>
+class semaphore final : public semaphore_base
+{
+	static_assert(Max >= 0 && Max < (1 << 30), "semaphore<>: Max is out of bounds");
+	static_assert(Def >= 0 && Def < (1 << 30), "semaphore<>: Def is out of bounds");
+	static_assert(Def <= Max, "semaphore<>: Def is too big");
+
+	using base = semaphore_base;
+
+public:
+	// Default constructor (recommended)
+	constexpr semaphore()
+		: base{Def << 1}
+	{
+	}
+
+	// Explicit value constructor (not recommended)
+	explicit constexpr semaphore(s32 value)
+		: base{value << 1}
+	{
+	}
+
+	// Obtain a semaphore
+	void wait()
+	{
+		return base::wait();
+	}
+
+	// Try to obtain a semaphore
+	explicit_bool_t try_wait()
+	{
+		return base::try_wait();
+	}
+
+	// Return a semaphore
+	void post()
+	{
+		return base::post(Max << 1);
+	}
+
+	// Try to return a semaphore
+	explicit_bool_t try_post()
+	{
+		return base::try_post(Max << 1);
+	}
+
+	// Get max semaphore value
+	static constexpr s32 size()
+	{
+		return Max;
+	}
+};