/*

 * Copyright (C) 2009 Apple Inc. All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 * 1. Redistributions of source code must retain the above copyright

 *    notice, this list of conditions and the following disclaimer.

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in the

 *    documentation and/or other materials provided with the distribution.

 *

 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY

 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR

 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,

 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,

 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR

 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY

 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 

 */

#ifndef MacroAssemblerCodeRef_h

#define MacroAssemblerCodeRef_h

#include "ExecutableAllocator.h"

#include "PassRefPtr.h"

#include "RefPtr.h"

#include "UnusedParam.h"

#if ENABLE(ASSEMBLER)

// ASSERT_VALID_CODE_POINTER checks that ptr is a non-null pointer, and that it is a valid

// instruction address on the platform (for example, check any alignment requirements).

#if CPU(ARM_THUMB2)

// ARM/thumb instructions must be 16-bit aligned, but all code pointers to be loaded

// into the processor are decorated with the bottom bit set, indicating that this is

// thumb code (as oposed to 32-bit traditional ARM).  The first test checks for both

// decorated and undectorated null, and the second test ensures that the pointer is

// decorated.

#define ASSERT_VALID_CODE_POINTER(ptr) \

    ASSERT(reinterpret_cast<intptr_t>(ptr) & ~1); \

    ASSERT(reinterpret_cast<intptr_t>(ptr) & 1)

#define ASSERT_VALID_CODE_OFFSET(offset) \

    ASSERT(!(offset & 1)) // Must be multiple of 2.

#else

#define ASSERT_VALID_CODE_POINTER(ptr) \

    ASSERT(ptr)

#define ASSERT_VALID_CODE_OFFSET(offset) // Anything goes!

#endif

namespace JSC {

// FunctionPtr:

//

// FunctionPtr should be used to wrap pointers to C/C++ functions in JSC

// (particularly, the stub functions).

class FunctionPtr {

public:

    FunctionPtr()

        : m_value(0)

    {

    }

    template<typename FunctionType>

    explicit FunctionPtr(FunctionType* value)

#if COMPILER(RVCT)

     // RVTC compiler needs C-style cast as it fails with the following error

     // Error:  #694: reinterpret_cast cannot cast away const or other type qualifiers

        : m_value((void*)(value))

#else

        : m_value(reinterpret_cast<void*>(value))

#endif

    {

        ASSERT_VALID_CODE_POINTER(m_value);

    }

    void* value() const { return m_value; }

    void* executableAddress() const { return m_value; }

private:

    void* m_value;

};

// ReturnAddressPtr:

//

// ReturnAddressPtr should be used to wrap return addresses generated by processor

// 'call' instructions exectued in JIT code.  We use return addresses to look up

// exception and optimization information, and to repatch the call instruction

// that is the source of the return address.

class ReturnAddressPtr {

public:

    ReturnAddressPtr()

        : m_value(0)

    {

    }

    explicit ReturnAddressPtr(void* value)

        : m_value(value)

    {

        ASSERT_VALID_CODE_POINTER(m_value);

    }

    explicit ReturnAddressPtr(FunctionPtr function)

        : m_value(function.value())

    {

        ASSERT_VALID_CODE_POINTER(m_value);

    }

    void* value() const { return m_value; }

private:

    void* m_value;

};

// MacroAssemblerCodePtr:

//

// MacroAssemblerCodePtr should be used to wrap pointers to JIT generated code.

class MacroAssemblerCodePtr {

public:

    MacroAssemblerCodePtr()

        : m_value(0)

    {

    }

    explicit MacroAssemblerCodePtr(void* value)

#if CPU(ARM_THUMB2)

        // Decorate the pointer as a thumb code pointer.

        : m_value(reinterpret_cast<char*>(value) + 1)

#else

        : m_value(value)

#endif

    {

        ASSERT_VALID_CODE_POINTER(m_value);

    }

    explicit MacroAssemblerCodePtr(ReturnAddressPtr ra)

        : m_value(ra.value())

    {

        ASSERT_VALID_CODE_POINTER(m_value);

    }

    void* executableAddress() const { return m_value; }

#if CPU(ARM_THUMB2)

    // To use this pointer as a data address remove the decoration.

    void* dataLocation() const { ASSERT_VALID_CODE_POINTER(m_value); return reinterpret_cast<char*>(m_value) - 1; }

#else

    void* dataLocation() const { ASSERT_VALID_CODE_POINTER(m_value); return m_value; }

#endif

    bool operator!()

    {

        return !m_value;

    }

private:

    void* m_value;

};

// MacroAssemblerCodeRef:

//

// A reference to a section of JIT generated code.  A CodeRef consists of a

// pointer to the code, and a ref pointer to the pool from within which it

// was allocated.

class MacroAssemblerCodeRef {

public:

    MacroAssemblerCodeRef()

        : m_size(0)

    {

    }

    MacroAssemblerCodeRef(void* code, PassRefPtr<ExecutablePool> executablePool, size_t size)

        : m_code(code)

        , m_executablePool(executablePool)

        , m_size(size)

    {

    }

    MacroAssemblerCodePtr m_code;

    RefPtr<ExecutablePool> m_executablePool;

    size_t m_size;

};

} // namespace JSC

#endif // ENABLE(ASSEMBLER)

#endif // MacroAssemblerCodeRef_h