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#include "qv4memberdata_p.h"
#include <private/qv4mm_p.h>
#include "qv4value_p.h"

using namespace QV4;

DEFINE_MANAGED_VTABLE(MemberData);

static size_t nextPowerOfTwo(size_t s)
{
    --s;
    s |= s >> 1;
    s |= s >> 2;
    s |= s >> 4;
    s |= s >> 8;
    s |= s >> 16;
#if (QT_POINTER_SIZE == 8)
        s |= s >> 32;
#endif
    ++s;
    return s;
}

Heap::MemberData *MemberData::allocate(ExecutionEngine *e, uint n, Heap::MemberData *old)
{
    Q_ASSERT(!old || old->values.size < n);
    Q_ASSERT(n);

    size_t alloc = MemoryManager::align(sizeof(Heap::MemberData) + (n - 1)*sizeof(Value));
    // round up to next power of two to avoid quadratic behaviour for very large objects
    alloc = nextPowerOfTwo(alloc);
    Heap::MemberData *m = e->memoryManager->allocManaged<MemberData>(alloc);
    if (old)
        // no write barrier required here
        memcpy(m, old, sizeof(Heap::MemberData) + (old->values.size - 1) * sizeof(Value));
    else
        m->init();
    m->values.alloc = static_cast<uint>((alloc - sizeof(Heap::MemberData) + sizeof(Value))/sizeof(Value));
    m->values.size = m->values.alloc;
    return m;
}
