/*

 * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 */

#ifndef SHARE_VM_RUNTIME_FLAGS_FLAGSETTING_HPP

#define SHARE_VM_RUNTIME_FLAGS_FLAGSETTING_HPP

#include "memory/allocation.hpp"

// debug flags control various aspects of the VM and are global accessible

// use FlagSetting to temporarily change some debug flag

// e.g. FlagSetting fs(DebugThisAndThat, true);

// restored to previous value upon leaving scope

class FlagSetting : public StackObj {

  bool val;

  bool* flag;

public:

  FlagSetting(bool& fl, bool newValue) { flag = &fl; val = fl; fl = newValue; }

  ~FlagSetting()                       { *flag = val; }

};

class UIntFlagSetting : public StackObj {

  uint val;

  uint* flag;

public:

  UIntFlagSetting(uint& fl, uint newValue) { flag = &fl; val = fl; fl = newValue; }

  ~UIntFlagSetting()                       { *flag = val; }

};

class SizeTFlagSetting : public StackObj {

  size_t val;

  size_t* flag;

public:

  SizeTFlagSetting(size_t& fl, size_t newValue) { flag = &fl; val = fl; fl = newValue; }

  ~SizeTFlagSetting()                           { *flag = val; }

};

// Helper class for temporarily saving the value of a flag during a scope.

template <size_t SIZE>

class FlagGuard {

  unsigned char _value[SIZE];

  void* const _addr;

public:

  FlagGuard(void* flag_addr) : _addr(flag_addr) { memcpy(_value, _addr, SIZE); }

  ~FlagGuard()                                  { memcpy(_addr, _value, SIZE); }

};

#define FLAG_GUARD(f) FlagGuard<sizeof(f)> f ## _guard(&f)

#endif // SHARE_VM_RUNTIME_FLAGS_FLAGSETTING_HPP