rpcsx/rpcs3/Emu/SysCalls/CB_FUNC.h

#pragma once
#include "Emu/Cell/PPUThread.h"

namespace cb_detail
{
	enum _func_arg_type
	{
		ARG_GENERAL,
		ARG_FLOAT,
		ARG_VECTOR,
		ARG_STACK,
	};

	// Current implementation can handle only fixed amount of stack arguments.
	// This constant can be increased if necessary.
	// It's possible to calculate suitable stack frame size in template, but too complicated.
	static const auto FIXED_STACK_FRAME_SIZE = 0x90;

	template<typename T, _func_arg_type type, int g_count, int f_count, int v_count>
	struct _func_arg;

	template<typename T, int g_count, int f_count, int v_count>
	struct _func_arg<T, ARG_GENERAL, g_count, f_count, v_count>
	{
		static_assert(sizeof(T) <= 8, "Invalid callback argument type for ARG_GENERAL");
		
		force_inline static void set_value(PPUThread& CPU, const T& arg)
		{
			CPU.GPR[g_count + 2] = cast_to_ppu_gpr<T>(arg);
		}
	};

	template<typename T, int g_count, int f_count, int v_count>
	struct _func_arg<T, ARG_FLOAT, g_count, f_count, v_count>
	{
		static_assert(sizeof(T) <= 8, "Invalid callback argument type for ARG_FLOAT");

		force_inline static void set_value(PPUThread& CPU, const T& arg)
		{
			CPU.FPR[f_count] = static_cast<T>(arg);
		}
	};

	template<typename T, int g_count, int f_count, int v_count>
	struct _func_arg<T, ARG_VECTOR, g_count, f_count, v_count>
	{
		static_assert(std::is_same<T, u128>::value, "Invalid callback argument type for ARG_VECTOR");

		force_inline static void set_value(PPUThread& CPU, const T& arg)
		{
			CPU.VPR[v_count + 1] = arg;
		}
	};

	template<typename T, int g_count, int f_count, int v_count>
	struct _func_arg<T, ARG_STACK, g_count, f_count, v_count>
	{
		static_assert(f_count <= 13, "TODO: Unsupported stack argument type (float)");
		static_assert(v_count <= 12, "TODO: Unsupported stack argument type (vector)");
		static_assert(sizeof(T) <= 8, "Invalid callback argument type for ARG_STACK");

		force_inline static void set_value(PPUThread& CPU, const T& arg)
		{
			const int stack_pos = (g_count - 9) * 8 - FIXED_STACK_FRAME_SIZE;
			static_assert(stack_pos < 0, "TODO: Increase fixed stack frame size (arg count limit broken)");
			vm::ps3::write64(CPU.GPR[1] + stack_pos, cast_to_ppu_gpr<T>(arg));
		}
	};

	template<int g_count, int f_count, int v_count>
	force_inline static bool _bind_func_args(PPUThread& CPU)
	{
		// terminator
		return false;
	}

	template<int g_count, int f_count, int v_count, typename T1, typename... T>
	force_inline static bool _bind_func_args(PPUThread& CPU, T1 arg1, T... args)
	{
		static_assert(!std::is_pointer<T1>::value, "Invalid callback argument type (pointer)");
		static_assert(!std::is_reference<T1>::value, "Invalid callback argument type (reference)");
		const bool is_float = std::is_floating_point<T1>::value;
		const bool is_vector = std::is_same<T1, u128>::value;
		const _func_arg_type t = is_float
			? ((f_count >= 13) ? ARG_STACK : ARG_FLOAT)
			: (is_vector ? ((v_count >= 12) ? ARG_STACK : ARG_VECTOR) : ((g_count >= 8) ? ARG_STACK : ARG_GENERAL));
		const int g = g_count + (is_float || is_vector ? 0 : 1);
		const int f = f_count + (is_float ? 1 : 0);
		const int v = v_count + (is_vector ? 1 : 0);
		
		_func_arg<T1, t, g, f, v>::set_value(CPU, arg1);
		// return true if stack was used
		return _bind_func_args<g, f, v>(CPU, args...) || (t == ARG_STACK);
	}

	template<typename T, _func_arg_type type>
	struct _func_res
	{
		static_assert(type == ARG_GENERAL, "Wrong use of _func_res template");
		static_assert(sizeof(T) <= 8, "Invalid callback result type for ARG_GENERAL");

		force_inline static T get_value(const PPUThread& CPU)
		{
			return cast_from_ppu_gpr<T>(CPU.GPR[3]);
		}
	};

	template<typename T>
	struct _func_res<T, ARG_FLOAT>
	{
		static_assert(sizeof(T) <= 8, "Invalid callback result type for ARG_FLOAT");

		force_inline static T get_value(const PPUThread& CPU)
		{
			return static_cast<T>(CPU.FPR[1]);
		}
	};

	template<typename T>
	struct _func_res<T, ARG_VECTOR>
	{
		static_assert(std::is_same<T, u128>::value, "Invalid callback result type for ARG_VECTOR");

		force_inline static T get_value(const PPUThread& CPU)
		{
			return CPU.VPR[2];
		}
	};

	template<typename RT, typename... T>
	struct _func_caller
	{
		force_inline static RT call(PPUThread& CPU, u32 pc, u32 rtoc, T... args)
		{
			_func_caller<void, T...>::call(CPU, pc, rtoc, args...);

			static_assert(!std::is_pointer<RT>::value, "Invalid callback result type (pointer)");
			static_assert(!std::is_reference<RT>::value, "Invalid callback result type (reference)");
			const bool is_float = std::is_floating_point<RT>::value;
			const bool is_vector = std::is_same<RT, u128>::value;
			const _func_arg_type t = is_float ? ARG_FLOAT : (is_vector ? ARG_VECTOR : ARG_GENERAL);

			return _func_res<RT, t>::get_value(CPU);
		}
	};

	template<typename... T>
	struct _func_caller<void, T...>
	{
		force_inline static void call(PPUThread& CPU, u32 pc, u32 rtoc, T... args)
		{
			const bool stack = _bind_func_args<0, 0, 0, T...>(CPU, args...);
			if (stack) CPU.GPR[1] -= FIXED_STACK_FRAME_SIZE;
			CPU.GPR[1] -= 0x70; // create reserved area
			CPU.FastCall2(pc, rtoc);
			CPU.GPR[1] += 0x70;
			if (stack) CPU.GPR[1] += FIXED_STACK_FRAME_SIZE;
		}
	};
}

namespace vm
{
	template<typename AT, typename RT, typename... T>
	force_inline RT _ptr_base<RT(T...), AT>::operator()(PPUThread& CPU, T... args) const
	{
		const auto data = vm::get_ptr<be_t<u32>>(VM_CAST(m_addr));
		const u32 pc = data[0];
		const u32 rtoc = data[1];

		return cb_detail::_func_caller<RT, T...>::call(CPU, pc, rtoc, args...);
	}
}

template<typename RT, typename... T>
force_inline RT cb_call(PPUThread& CPU, u32 pc, u32 rtoc, T... args)
{
	return cb_detail::_func_caller<RT, T...>::call(CPU, pc, rtoc, args...);
}

// Something is wrong with it (but cb_call<void, ...>() should work anyway)
//template<typename... T>
//void cb_call(PPUThread& CPU, u32 pc, u32 rtoc, T... args)
//{
//	cb_detail::_func_caller<void, T...>::call(CPU, pc, rtoc, args...);
//}