godot/core/safe_refcount.h
Pedro J. Estébanez 27637b9e7f Improve/add atomics
- Remove use of non-builtin overloaded `InterlockedExhangeSubtract()` for Windows. Moreover, it was wrongly being used as if it hadn't a 64-bit version instead of being overloaded.
- Implement exchange-if-greater (as a CAS loop).
2017-07-25 01:49:22 +02:00

91 lines
3.6 KiB
C++

/*************************************************************************/
/* safe_refcount.h */
/*************************************************************************/
/* This file is part of: */
/* GODOT ENGINE */
/* http://www.godotengine.org */
/*************************************************************************/
/* Copyright (c) 2007-2017 Juan Linietsky, Ariel Manzur. */
/* Copyright (c) 2014-2017 Godot Engine contributors (cf. AUTHORS.md) */
/* */
/* Permission is hereby granted, free of charge, to any person obtaining */
/* a copy of this software and associated documentation files (the */
/* "Software"), to deal in the Software without restriction, including */
/* without limitation the rights to use, copy, modify, merge, publish, */
/* distribute, sublicense, and/or sell copies of the Software, and to */
/* permit persons to whom the Software is furnished to do so, subject to */
/* the following conditions: */
/* */
/* The above copyright notice and this permission notice shall be */
/* included in all copies or substantial portions of the Software. */
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/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, */
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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