// license:BSD-3-Clause // copyright-holders:Aaron Giles,Couriersud,Miodrag Milanovic /*************************************************************************** delegate.h Templates and classes to enable delegates for callbacks. **************************************************************************** There are many implementations of delegate-like functionality for C++ code, but none of them is a perfect drop-in fit for use in MAME. In order to be useful in MAME, we need the following properties: * No significant overhead; we want to use these for memory accessors, and memory accessor overhead is already the dominant performance aspect for most drivers. * Existing static functions need to be bound with an additional pointer parameter as the first argument. All existing implementations that allow static function binding assume the same signature as the member functions. * We must be able to bind the function separately from the object. This is to allow configurations to bind functions before the objects are created. Thus, the implementations below are based on existing works but are really a new implementation that is specific to MAME. -------------------------------------------------------------------- The "compatible" version of delegates is based on an implementation from Sergey Ryazanov, found here: http://www.codeproject.com/KB/cpp/ImpossiblyFastCppDelegate.aspx These delegates essentially generate a templated static stub function for each target function. The static function takes the first parameter, uses it as the object pointer, and calls through the member function. For static functions, the stub is compatible with the signature of a static function, so we just set the stub directly. Pros: * should work with any modern compiler * static bindings are just as fast as direct calls Cons: * lots of little stub functions generated * double-hops on member function calls means more overhead * calling through stub functions repackages parameters -------------------------------------------------------------------- The "internal" version of delegates makes use of the internal structure of member function pointers in order to convert them at binding time into simple static function pointers. This only works on platforms where object->func(p1, p2) is equivalent in calling convention to func(object, p1, p2). Most of the information on how this works comes from Don Clugston in this article: http://www.codeproject.com/KB/cpp/FastDelegate.aspx Pros: * as fast as a standard function call in static and member cases * no stub functions or double-hops needed Cons: * requires internal knowledge of the member function pointer * only works for GCC (for now; MSVC info is also readily available) ***************************************************************************/ #pragma once #ifndef __DELEGATE_H__ #define __DELEGATE_H__ // standard C++ includes #include #include #include #include //************************************************************************** // MACROS //************************************************************************** // types of delegates supported #define DELEGATE_TYPE_COMPATIBLE 0 #define DELEGATE_TYPE_INTERNAL 1 #define DELEGATE_TYPE_MSVC 2 // select which one we will be using #if defined(__GNUC__) /* 32bit MINGW asks for different convention */ #if defined(__MINGW32__) && !defined(__x86_64) && defined(__i386__) #define USE_DELEGATE_TYPE DELEGATE_TYPE_INTERNAL #define MEMBER_ABI __thiscall #define HAS_DIFFERENT_ABI 1 #elif defined(__clang__) && defined(__i386__) && defined(_WIN32) #define USE_DELEGATE_TYPE DELEGATE_TYPE_COMPATIBLE #else #define USE_DELEGATE_TYPE DELEGATE_TYPE_INTERNAL #define MEMBER_ABI #define HAS_DIFFERENT_ABI 0 #endif #elif defined(_MSC_VER) && defined (_M_X64) #define MEMBER_ABI #define HAS_DIFFERENT_ABI 0 #define USE_DELEGATE_TYPE DELEGATE_TYPE_MSVC #else #define USE_DELEGATE_TYPE DELEGATE_TYPE_COMPATIBLE #endif #if defined(FORCE_COMPATIBLE) #undef USE_DELEGATE_TYPE #undef MEMBER_ABI #undef HAS_DIFFERENT_ABI #define USE_DELEGATE_TYPE DELEGATE_TYPE_COMPATIBLE #endif #if (USE_DELEGATE_TYPE == DELEGATE_TYPE_COMPATIBLE) #define MEMBER_ABI #define HAS_DIFFERENT_ABI 0 #endif //************************************************************************** // HELPER CLASSES //************************************************************************** // generic function type using delegate_generic_function = void(*)(); // ======================> generic_class // define a dummy generic class that is just straight single-inheritance #ifdef _MSC_VER class __single_inheritance generic_class; class delegate_generic_class { }; #else class delegate_generic_class; #endif // ======================> delegate_late_bind // simple polymorphic class that must be mixed into any object that is late-bound class delegate_late_bind { public: delegate_late_bind() { } virtual ~delegate_late_bind() { } }; // ======================> binding_type_exception // exception that is thrown when a bind fails the dynamic_cast class binding_type_exception : public std::exception { public: binding_type_exception(const std::type_info &target_type, const std::type_info &actual_type) : m_target_type(target_type), m_actual_type(actual_type) { } const std::type_info &m_target_type; const std::type_info &m_actual_type; }; // ======================> delegate_traits // delegate_traits is a meta-template that is used to provide a static function pointer // and member function pointer of the appropriate type and number of parameters template struct delegate_traits { using static_func_type = _ReturnType(*)(_ClassType *, Params...); using static_ref_func_type = _ReturnType(*)(_ClassType &, Params...); using member_func_type = _ReturnType(_ClassType::*)(Params...); using const_member_func_type = _ReturnType(_ClassType::*)(Params...) const; }; //************************************************************************** // DELEGATE MEMBER FUNCTION POINTER WRAPPERS //************************************************************************** #if (USE_DELEGATE_TYPE == DELEGATE_TYPE_COMPATIBLE) // ======================> delegate_mfp // delegate_mfp is a class that wraps a generic member function pointer // in a static buffer, and can effectively recast itself back for later use; // it hides some of the gross details involved in copying arbitrary member // function pointers around class delegate_mfp { public: // default constructor delegate_mfp() : m_rawdata(s_null_mfp), m_realobject(nullptr), m_stubfunction(nullptr) { } // copy constructor delegate_mfp(const delegate_mfp &src) : m_rawdata(src.m_rawdata), m_realobject(src.m_realobject), m_stubfunction(src.m_stubfunction) { } // construct from any member function pointer template delegate_mfp(_MemberFunctionType mfp, _MemberFunctionClass *, _ReturnType *, _StaticFunctionType) : m_rawdata(s_null_mfp), m_realobject(nullptr), m_stubfunction(make_generic<_StaticFunctionType>(&delegate_mfp::method_stub<_MemberFunctionClass, _ReturnType>)) { assert(sizeof(mfp) <= sizeof(m_rawdata)); *reinterpret_cast<_MemberFunctionType *>(&m_rawdata) = mfp; } // comparison helpers bool operator==(const delegate_mfp &rhs) const { return (m_rawdata == rhs.m_rawdata); } bool isnull() const { return (m_rawdata == s_null_mfp); } // getters delegate_generic_class *real_object(delegate_generic_class *original) const { return m_realobject; } // binding helper template void update_after_bind(_FunctionType &funcptr, delegate_generic_class *&object) { m_realobject = object; object = reinterpret_cast(this); funcptr = reinterpret_cast<_FunctionType>(m_stubfunction); } private: // helper stubs for calling encased member function pointers template static _ReturnType method_stub(delegate_generic_class *object, Params ... args) { delegate_mfp *_this = reinterpret_cast(object); using mfptype = _ReturnType(_FunctionClass::*)(Params...); mfptype &mfp = *reinterpret_cast(&_this->m_rawdata); return (reinterpret_cast<_FunctionClass *>(_this->m_realobject)->*mfp)(std::forward(args)...); } // helper to convert a function of a given type to a generic function, forcing template // instantiation to match the source type template static delegate_generic_function make_generic(_SourceType funcptr) { return reinterpret_cast(funcptr); } struct raw_mfp_data { #if defined (__INTEL_COMPILER) && defined (_M_X64) // needed for "Intel(R) C++ Intel(R) 64 Compiler XE for applications running on Intel(R) 64, Version 14.0.2.176 Build 20140130" at least int data[((sizeof(void *) + 4 * sizeof(int)) + (sizeof(int) - 1)) / sizeof(int)]; #else // all other cases - for MSVC maximum size is one pointer, plus 3 ints; all other implementations seem to be smaller int data[((sizeof(void *) + 3 * sizeof(int)) + (sizeof(int) - 1)) / sizeof(int)]; #endif bool operator==(const raw_mfp_data &rhs) const { return (memcmp(data, rhs.data, sizeof(data)) == 0); } }; // internal state raw_mfp_data m_rawdata; // raw buffer to hold the copy of the function pointer delegate_generic_class * m_realobject; // pointer to the object used for calling delegate_generic_function m_stubfunction; // pointer to our matching stub function static raw_mfp_data s_null_mfp; // nullptr mfp }; #elif (USE_DELEGATE_TYPE == DELEGATE_TYPE_INTERNAL) // ======================> delegate_mfp // struct describing the contents of a member function pointer class delegate_mfp { public: // default constructor delegate_mfp() : m_function(0), m_this_delta(0) { } // copy constructor delegate_mfp(const delegate_mfp &src) : m_function(src.m_function), m_this_delta(src.m_this_delta) { } // construct from any member function pointer template delegate_mfp(_MemberFunctionType mfp, _MemberFunctionClass *, _ReturnType *, _StaticFunctionType) { assert(sizeof(mfp) == sizeof(*this)); *reinterpret_cast<_MemberFunctionType *>(this) = mfp; } // comparison helpers bool operator==(const delegate_mfp &rhs) const { return (m_function == rhs.m_function && m_this_delta == rhs.m_this_delta); } bool isnull() const { return (m_function == 0 && m_this_delta==0); } // getters static delegate_generic_class *real_object(delegate_generic_class *original) { return original; } // binding helper template void update_after_bind(_FunctionType &funcptr, delegate_generic_class *&object) { funcptr = reinterpret_cast<_FunctionType>(convert_to_generic(object)); } private: // extract the generic function and adjust the object pointer delegate_generic_function convert_to_generic(delegate_generic_class *&object) const; // actual state uintptr_t m_function; // first item can be one of two things: // if even, it's a pointer to the function // if odd, it's the byte offset into the vtable int m_this_delta; // delta to apply to the 'this' pointer }; #elif (USE_DELEGATE_TYPE == DELEGATE_TYPE_MSVC) // ======================> delegate_mfp const int SINGLE_MEMFUNCPTR_SIZE = sizeof(void (delegate_generic_class::*)()); // struct describing the contents of a member function pointer class delegate_mfp { public: // default constructor delegate_mfp() : m_function(0), m_this_delta(0), m_dummy1(0), m_dummy2(0), m_size(0) { } // copy constructor delegate_mfp(const delegate_mfp &src) : m_function(src.m_function), m_this_delta(0), m_dummy1(0), m_dummy2(0), m_size(0) { } // construct from any member function pointer template delegate_mfp(_MemberFunctionType mfp, _MemberFunctionClass *, _ReturnType *, _StaticFunctionType) { //assert(sizeof(mfp) == 12 || sizeof(mfp) == 16); m_size = sizeof(mfp); *reinterpret_cast<_MemberFunctionType *>(this) = mfp; } // comparison helpers bool operator==(const delegate_mfp &rhs) const { return (m_function == rhs.m_function); } bool isnull() const { return (m_function == 0); } // getters static delegate_generic_class *real_object(delegate_generic_class *original) { return original; } // binding helper template void update_after_bind(_FunctionType &funcptr, delegate_generic_class *&object) { funcptr = reinterpret_cast<_FunctionType>(m_function); if (m_size == SINGLE_MEMFUNCPTR_SIZE + sizeof(int)) object = reinterpret_cast(reinterpret_cast(object) + m_this_delta); } private: // extract the generic function and adjust the object pointer delegate_generic_function convert_to_generic(delegate_generic_class *&object) const; // actual state uintptr_t m_function; // first item can be one of two things: // if even, it's a pointer to the function // if odd, it's the byte offset into the vtable int m_this_delta; // delta to apply to the 'this' pointer int m_dummy1; int m_dummy2; int m_size; }; #endif //************************************************************************** // COMMON DELEGATE BASE CLASS //************************************************************************** // ======================> delegate_base // general delegate class template supporting up to 5 parameters template class delegate_base { public: // define our traits template struct traits { using member_func_type = typename delegate_traits<_FunctionClass, _ReturnType, Params...>::member_func_type; using const_member_func_type = typename delegate_traits<_FunctionClass, _ReturnType, Params...>::const_member_func_type; using static_func_type = typename delegate_traits<_FunctionClass, _ReturnType, Params...>::static_func_type; using static_ref_func_type = typename delegate_traits<_FunctionClass, _ReturnType, Params...>::static_ref_func_type; }; using functional_type = std::function<_ReturnType(Params...)>; using generic_static_func = typename traits::static_func_type; typedef MEMBER_ABI generic_static_func generic_member_func; // generic constructor delegate_base() : m_function(nullptr), m_object(nullptr), m_latebinder(nullptr), m_raw_function(nullptr), m_std_func(nullptr){ } // copy constructor delegate_base(const delegate_base &src) : m_function(src.m_function), m_object(nullptr), m_latebinder(src.m_latebinder), m_raw_function(src.m_raw_function), m_raw_mfp(src.m_raw_mfp), m_std_func(src.m_std_func) { bind(src.object()); } // copy constructor with late bind delegate_base(const delegate_base &src, delegate_late_bind &object) : m_function(src.m_function), m_object(nullptr), m_latebinder(src.m_latebinder), m_raw_function(src.m_raw_function), m_raw_mfp(src.m_raw_mfp), m_std_func(src.m_std_func) { late_bind(object); } // construct from member function with object pointer template delegate_base(typename traits<_FunctionClass>::member_func_type funcptr, _FunctionClass *object) : m_function(nullptr), m_object(nullptr), m_latebinder(&late_bind_helper<_FunctionClass>), m_raw_function(nullptr), m_raw_mfp(funcptr, object, static_cast<_ReturnType *>(nullptr), static_cast(nullptr)), m_std_func(nullptr) { bind(reinterpret_cast(object)); } template delegate_base(typename traits<_FunctionClass>::const_member_func_type funcptr, _FunctionClass *object) : m_function(nullptr), m_object(nullptr), m_latebinder(&late_bind_helper<_FunctionClass>), m_raw_function(nullptr), m_raw_mfp(funcptr, object, static_cast<_ReturnType *>(nullptr), static_cast(nullptr)), m_std_func(nullptr) { bind(reinterpret_cast(object)); } // construct from static function with object pointer template delegate_base(typename traits<_FunctionClass>::static_func_type funcptr, _FunctionClass *object) : m_function(reinterpret_cast(funcptr)), m_object(nullptr), m_latebinder(&late_bind_helper<_FunctionClass>), m_raw_function(reinterpret_cast(funcptr)), m_std_func(nullptr) { bind(reinterpret_cast(object)); } // construct from static reference function with object reference template delegate_base(typename traits<_FunctionClass>::static_ref_func_type funcptr, _FunctionClass *object) : m_function(reinterpret_cast(funcptr)), m_object(nullptr), m_latebinder(&late_bind_helper<_FunctionClass>), m_raw_function(reinterpret_cast(funcptr)), m_std_func(nullptr) { bind(reinterpret_cast(object)); } // construct from static reference function with object reference delegate_base(functional_type funcptr) : m_function(nullptr), m_object(nullptr), m_latebinder(nullptr), m_raw_function(nullptr), m_std_func(funcptr) { } // copy operator delegate_base &operator=(const delegate_base &src) { if (this != &src) { m_function = src.m_function; m_object = nullptr; m_latebinder = src.m_latebinder; m_raw_function = src.m_raw_function; m_raw_mfp = src.m_raw_mfp; m_std_func = src.m_std_func; bind(src.object()); } return *this; } // comparison helper bool operator==(const delegate_base &rhs) const { return (m_raw_function == rhs.m_raw_function && object() == rhs.object() && m_raw_mfp == rhs.m_raw_mfp && m_std_func.target_type().name() == rhs.m_std_func.target_type().name()); } // call the function _ReturnType operator()(Params... args) const { if (is_mfp() && (HAS_DIFFERENT_ABI)) return (*reinterpret_cast(m_function)) (m_object, std::forward(args)...); else if (m_std_func) return m_std_func(std::forward(args)...); else return (*m_function) (m_object, std::forward(args)...); } // getters bool has_object() const { return (object() != nullptr) || m_std_func; } // helpers bool isnull() const { return (m_raw_function == nullptr && m_raw_mfp.isnull() && !m_std_func); } bool is_mfp() const { return !m_raw_mfp.isnull(); } // late binding void late_bind(delegate_late_bind &object) { if(m_latebinder) bind((*m_latebinder)(object)); } protected: // return the actual object (not the one we use for calling) delegate_generic_class *object() const { return is_mfp() ? m_raw_mfp.real_object(m_object) : m_object; } // late binding function using late_bind_func = delegate_generic_class*(*)(delegate_late_bind &object); // late binding helper template static delegate_generic_class *late_bind_helper(delegate_late_bind &object) { _FunctionClass *result = dynamic_cast<_FunctionClass *>(&object); if (result == nullptr) { throw binding_type_exception(typeid(_FunctionClass), typeid(object)); } return reinterpret_cast(result); } // bind the actual object void bind(delegate_generic_class *object) { m_object = object; // if we're wrapping a member function pointer, handle special stuff if (m_object != nullptr && is_mfp()) m_raw_mfp.update_after_bind(m_function, m_object); } // internal state generic_static_func m_function; // resolved static function pointer delegate_generic_class * m_object; // resolved object to the post-cast object late_bind_func m_latebinder; // late binding helper generic_static_func m_raw_function; // raw static function pointer delegate_mfp m_raw_mfp; // raw member function pointer functional_type m_std_func; // std::function pointer }; //************************************************************************** // NATURAL SYNTAX //************************************************************************** // declare the base template template class delegate; template class delegate<_ReturnType (Params...)> : public delegate_base<_ReturnType, Params...> { using basetype = delegate_base<_ReturnType, Params...>; public: // create a standard set of constructors delegate() : basetype() { } explicit delegate(const basetype &src) : basetype(src) { } delegate(const basetype &src, delegate_late_bind &object) : basetype(src, object) { } template delegate(typename basetype::template traits<_FunctionClass>::member_func_type funcptr, _FunctionClass *object) : basetype(funcptr, object) { } template delegate(typename basetype::template traits<_FunctionClass>::const_member_func_type funcptr, _FunctionClass *object) : basetype(funcptr, object) { } explicit delegate(std::function<_ReturnType(Params...)> funcptr) : basetype(funcptr) { } template delegate(typename basetype::template traits<_FunctionClass>::static_func_type funcptr, _FunctionClass *object) : basetype(funcptr, object) { } template delegate(typename basetype::template traits<_FunctionClass>::static_ref_func_type funcptr,_FunctionClass *object) : basetype(funcptr, object) { } delegate &operator=(const basetype &src) { *static_cast(this) = src; return *this; } }; #endif /* __DELEGATE_H__ */