godot/core/safe_refcount.h

/*************************************************************************/
/*  safe_refcount.h                                                      */
/*************************************************************************/
/*                       This file is part of:                           */
/*                           GODOT ENGINE                                */
/*                    http://www.godotengine.org                         */
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/* Copyright (c) 2007-2017 Juan Linietsky, Ariel Manzur.                 */
/* Copyright (c) 2014-2017 Godot Engine contributors (cf. AUTHORS.md)    */
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#ifndef SAFE_REFCOUNT_H
#define SAFE_REFCOUNT_H

#include "os/mutex.h"
/* x86/x86_64 GCC */

#include "platform_config.h"
#include "typedefs.h"

uint32_t atomic_conditional_increment(register uint32_t *counter);
uint32_t atomic_decrement(register uint32_t *pw);
uint32_t atomic_increment(register uint32_t *pw);
uint32_t atomic_sub(register uint32_t *pw, register uint32_t val);
uint32_t atomic_add(register uint32_t *pw, register uint32_t val);
uint32_t atomic_exchange_if_greater(register uint32_t *pw, register uint32_t val);

uint64_t atomic_conditional_increment(register uint64_t *counter);
uint64_t atomic_decrement(register uint64_t *pw);
uint64_t atomic_increment(register uint64_t *pw);
uint64_t atomic_sub(register uint64_t *pw, register uint64_t val);
uint64_t atomic_add(register uint64_t *pw, register uint64_t val);
uint64_t atomic_exchange_if_greater(register uint64_t *pw, register uint64_t val);

struct SafeRefCount {

	uint32_t count;

public:
	// destroy() is called when weak_count_ drops to zero.

	bool ref() { //true on success

		return atomic_conditional_increment(&count) != 0;
	}

	uint32_t refval() { //true on success

		return atomic_conditional_increment(&count);
	}

	bool unref() { // true if must be disposed of

		if (atomic_decrement(&count) == 0) {
			return true;
		}

		return false;
	}

	uint32_t get() const { // nothrow

		return count;
	}

	void init(uint32_t p_value = 1) {

		count = p_value;
	}
};

#endif