/****************************************************************************
**
** Copyright (C) 2014 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
**
** This file is part of the QtCore module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL21$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Digia. For licensing terms and
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** use the contact form at http://qt.digia.com/contact-us.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 or version 3 as published by the Free
** Software Foundation and appearing in the file LICENSE.LGPLv21 and
** LICENSE.LGPLv3 included in the packaging of this file. Please review the
** following information to ensure the GNU Lesser General Public License
** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
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**
** In addition, as a special exception, Digia gives you certain additional
** rights. These rights are described in the Digia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
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** $QT_END_LICENSE$
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****************************************************************************/

#include "qplatformdefs.h"

#include <stdlib.h>

/*
    Define the container allocation functions in a separate file, so that our
    users can easily override them.
*/

QT_BEGIN_NAMESPACE

#if !QT_DEPRECATED_SINCE(5, 0)
// Make sure they're defined to be exported
Q_CORE_EXPORT void *qMalloc(size_t size) Q_ALLOC_SIZE(1);
Q_CORE_EXPORT void qFree(void *ptr);
Q_CORE_EXPORT void *qRealloc(void *ptr, size_t size) Q_ALLOC_SIZE(2);
#endif


void *qMalloc(size_t size)
{
    return ::malloc(size);
}

void qFree(void *ptr)
{
    ::free(ptr);
}

void *qRealloc(void *ptr, size_t size)
{
    return ::realloc(ptr, size);
}

void *qMallocAligned(size_t size, size_t alignment)
{
    return qReallocAligned(0, size, 0, alignment);
}

void *qReallocAligned(void *oldptr, size_t newsize, size_t oldsize, size_t alignment)
{
    // fake an aligned allocation
    Q_UNUSED(oldsize);

    void *actualptr = oldptr ? static_cast<void **>(oldptr)[-1] : 0;
    if (alignment <= sizeof(void*)) {
        // special, fast case
        void **newptr = static_cast<void **>(realloc(actualptr, newsize + sizeof(void*)));
        if (!newptr)
            return 0;
        if (newptr == actualptr) {
            // realloc succeeded without reallocating
            return oldptr;
        }

        *newptr = newptr;
        return newptr + 1;
    }

    // malloc returns pointers aligned at least at sizeof(size_t) boundaries
    // but usually more (8- or 16-byte boundaries).
    // So we overallocate by alignment-sizeof(size_t) bytes, so we're guaranteed to find a
    // somewhere within the first alignment-sizeof(size_t) that is properly aligned.

    // However, we need to store the actual pointer, so we need to allocate actually size +
    // alignment anyway.

    void *real = realloc(actualptr, newsize + alignment);
    if (!real)
        return 0;

    quintptr faked = reinterpret_cast<quintptr>(real) + alignment;
    faked &= ~(alignment - 1);

    void **faked_ptr = reinterpret_cast<void **>(faked);

    // now save the value of the real pointer at faked-sizeof(void*)
    // by construction, alignment > sizeof(void*) and is a power of 2, so
    // faked-sizeof(void*) is properly aligned for a pointer
    faked_ptr[-1] = real;

    return faked_ptr;
}

void qFreeAligned(void *ptr)
{
    if (!ptr)
        return;
    void **ptr2 = static_cast<void **>(ptr);
    free(ptr2[-1]);
}

QT_END_NAMESPACE

