root/core/AtomWriteBarrier.h

INCLUDED FROM

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#ifndef __avmplus_AtomWriteBarrier__
#define __avmplus_AtomWriteBarrier__


namespace avmplus
{
                // Optimized Atom write barrier
                class AtomWB
                {
                public:
                        explicit AtomWB() : m_atom(nullObjectAtom) 
                        {
                                // nothing
                        }

                        explicit AtomWB(Atom t)  // : m_atom(t) -- not necessary, atomWriteBarrier_ctor handles it
                        { 
                                MMgc::GC* const gc = MMgc::GC::GetGC(this);
                                void* const container = gc->FindBeginningFast(this);
                                AvmCore::atomWriteBarrier_ctor(gc, container, &m_atom, t);
                        }

                        ~AtomWB() 
                        { 
                                AvmCore::atomWriteBarrier_dtor(&m_atom);
                        }

                        Atom operator=(Atom tNew)
                        {
                                MMgc::GC* const gc = MMgc::GC::GetGC(this);
                                void* const container = gc->FindBeginningFast(this);
                                set(gc, container, tNew);
                                return tNew;
                        }
                        
                        // if you know the container, this saves a call to FindBeginningFast...
                        // which adds up in (e.g.) heavy E4X usage
                        inline void set(MMgc::GC* gc, const void* container, Atom atomNew)
                        {
                                if (m_atom != atomNew)
                                {
                                        AvmCore::atomWriteBarrier(gc, container, &m_atom, atomNew);
                                }
                        }

                        inline operator const Atom&() const { return m_atom; }

                private:
                        explicit AtomWB(const AtomWB& toCopy); // unimplemented
                        void operator=(const AtomWB& wb); // unimplemented
                        
                        Atom set(Atom atomNew)
                        {
                                if (m_atom != atomNew)
                                {
                                        MMgc::GC* gc = MMgc::GC::GetGC(this);
                                        AvmCore::atomWriteBarrier(gc, gc->FindBeginningFast(this), &m_atom, atomNew);
                                }
                                return atomNew;
                        }
                        Atom m_atom;
                };
#define ATOM_WB AtomWB
#define WBATOM(gc, c, a, v) AvmCore::atomWriteBarrier(gc, c, a, v)
}

#endif /* __avmplus_AtomWriteBarrier__ */