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// license:BSD-3-Clause
// copyright-holders:Aaron Giles,Vas Crabb
/***************************************************************************
delegate.cpp
Templates and classes to enable delegates for callbacks.
***************************************************************************/
#include "delegate.h"
#include <cstdio>
#include <sstream>
//**************************************************************************
// MACROS
//**************************************************************************
#if defined(MAME_DELEGATE_LOG_ADJ)
#define LOG(...) printf(__VA_ARGS__)
#else
#define LOG(...) do { if (false) printf(__VA_ARGS__); } while (false)
#endif
// on some architectures, function pointers point to descriptors
// usually this is a global pointer value along with the branch target
// other platforms using this convention include:
// * AIX, Classic MacOS and WinNT on 32-bit POWER/PowerPC
// * pretty much anything on Itanium
#if (defined(__ppc64__) || (defined(__PPC64__))) && !defined(__APPLE__)
#define MAME_DELEGATE_VT_DESCRIPTOR 1
#endif
#ifndef MAME_DELEGATE_VT_DESCRIPTOR
#define MAME_DELEGATE_VT_DESCRIPTOR 0
#endif
//**************************************************************************
// LATE BINDING EXCEPTION
//**************************************************************************
binding_type_exception::binding_type_exception(std::type_info const &target_type, std::type_info const &actual_type)
: m_target_type(&target_type)
, m_actual_type(&actual_type)
{
std::ostringstream os;
os << "Error performing late bind of function expecting type " << target_type.name() << " to instance of type " << actual_type.name();
m_what = os.str();
}
char const *binding_type_exception::what() const noexcept
{
return m_what.c_str();
}
namespace util::detail {
//**************************************************************************
// GLOBAL VARIABLES
//**************************************************************************
const delegate_mfp_compatible::raw_mfp_data delegate_mfp_compatible::s_null_mfp = { { 0 } };
//**************************************************************************
// INTERNAL DELEGATE HELPERS
//**************************************************************************
//-------------------------------------------------
// delegate_mfp_itanium::convert_to_generic -
// given an object pointer and member function
// pointer, apply the displacement and get the
// actual function pointer
//-------------------------------------------------
delegate_generic_function delegate_mfp_itanium::convert_to_generic(delegate_generic_class *&object) const
{
// apply the "this" delta to the object first - the value is shifted to the left one bit position for the ARM-like variant
LOG("Input this=%p ptr=%p adj=%ld ", reinterpret_cast<void const *>(object), reinterpret_cast<void const *>(m_function), long(m_this_delta));
object = reinterpret_cast<delegate_generic_class *>(
reinterpret_cast<std::uint8_t *>(object) + (m_this_delta >> (MAME_DELEGATE_ITANIUM_ARM ? 1 : 0)));
LOG("Calculated this=%p ", reinterpret_cast<void const *>(object));
// test the virtual member function flag - it's the low bit of either the ptr or adj field, depending on the variant
if (MAME_DELEGATE_ITANIUM_ARM ? !(m_this_delta & 1) : !(m_function & 1))
{
// conventional function pointer
LOG("ptr=%p\n", reinterpret_cast<void const *>(m_function));
return reinterpret_cast<delegate_generic_function>(m_function);
}
else
{
// byte index into the vtable to the function
std::uint8_t const *const vtable_ptr = *reinterpret_cast<std::uint8_t const *const *>(object) + m_function - (MAME_DELEGATE_ITANIUM_ARM ? 0 : 1);
delegate_generic_function result;
if (MAME_DELEGATE_VT_DESCRIPTOR)
result = reinterpret_cast<delegate_generic_function>(uintptr_t(vtable_ptr));
else
result = *reinterpret_cast<delegate_generic_function const *>(vtable_ptr);
LOG("ptr=%p (vtable)\n", reinterpret_cast<void const *>(result));
return result;
}
}
//-------------------------------------------------
// delegate_mfp_msvc::adjust_this_pointer - given
// an object pointer and member function pointer,
// apply the displacement, and walk past
// recognisable thunks
//-------------------------------------------------
delegate_generic_function delegate_mfp_msvc::adjust_this_pointer(delegate_generic_class *&object) const
{
LOG("Input this=%p ", reinterpret_cast<void const *>(object));
if (sizeof(single_base_equiv) < m_size)
LOG("thisdelta=%d ", m_this_delta);
if (sizeof(unknown_base_equiv) == m_size)
LOG("vptrdelta=%d vindex=%d ", m_vptr_offs, m_vt_index);
std::uint8_t *byteptr = reinterpret_cast<std::uint8_t *>(object);
// test for pointer to member function cast across virtual inheritance relationship
if ((sizeof(unknown_base_equiv) == m_size) && m_vt_index)
{
// add offset from "this" pointer to location of vptr, and add offset to virtual base from vtable
byteptr += m_vptr_offs;
std::uint8_t const *const vptr = *reinterpret_cast<std::uint8_t const *const *>(byteptr);
byteptr += *reinterpret_cast<int const *>(vptr + m_vt_index);
}
// add "this" pointer displacement if present in the pointer to member function
if (sizeof(single_base_equiv) < m_size)
byteptr += m_this_delta;
LOG("Calculated this=%p\n", reinterpret_cast<void const *>(byteptr));
object = reinterpret_cast<delegate_generic_class *>(byteptr);
// walk past recognisable thunks
std::uint8_t const *func = reinterpret_cast<std::uint8_t const *>(m_function);
#if defined(__x86_64__) || defined(_M_X64)
while (true)
{
if (0xe9 == func[0])
{
// absolute jump with 32-bit displacement
LOG("Found relative jump at %p ", func);
func += 5 + *reinterpret_cast<std::int32_t const *>(func + 1);
LOG("redirecting to %p\n", func);
}
else if ((0x48 == func[0]) && (0x8b == func[1]) && (0x01 == func[2]) && (0xff == func[3]) && ((0x60 == func[4]) || (0xa0 == func[4])))
{
// virtual function call thunk - mov rax,QWORD PTR [rcx] ; jmp QWORD PTR [rax+...]
LOG("Found virtual member function thunk at %p ", func);
std::uint8_t const *const vptr = *reinterpret_cast<std::uint8_t const *const *>(object);
if (0x60 == func[4])
func = *reinterpret_cast<std::uint8_t const *const *>(vptr + *reinterpret_cast<std::int8_t const *>(func + 5));
else
func = *reinterpret_cast<std::uint8_t const *const *>(vptr + *reinterpret_cast<std::int32_t const *>(func + 5));
LOG("redirecting to %p\n", func);
}
else
{
// not something we can easily bypass
break;
}
}
#endif
return reinterpret_cast<delegate_generic_function>(std::uintptr_t(func));
}
} // namespace util::detail
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