From 69eb1f210f74982c2b2df0432675ea195b075e35 Mon Sep 17 00:00:00 2001
From: shad0wshayd3 <shad0wshayd3@users.noreply.github.com>
Date: Thu, 14 Nov 2024 20:24:33 -0700
Subject: [PATCH] feat: Relocation::write_func (#298)

---
 include/REL/Relocation.h | 12 ++++++++++++
 src/REL/Relocation.cpp   | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 44 insertions(+)
 create mode 100644 src/REL/Relocation.cpp

diff --git a/include/REL/Relocation.h b/include/REL/Relocation.h
index 4a73f2b8..9babdb4c 100644
--- a/include/REL/Relocation.h
+++ b/include/REL/Relocation.h
@@ -338,6 +338,18 @@ namespace REL
 			safe_fill(address(), a_value, a_count);
 		}
 
+#ifdef SFSE_SUPPORT_XBYAK
+		void write_func(const std::size_t a_count, const std::uintptr_t a_dst)
+			requires(std::same_as<value_type, std::uintptr_t>);
+
+		template <class F>
+		void write_func(const std::size_t a_count, const F a_dst)
+			requires(std::same_as<value_type, std::uintptr_t>)
+		{
+			write_func(a_count, stl::unrestricted_cast<std::uintptr_t>(a_dst));
+		}
+#endif
+
 		constexpr std::uintptr_t write_vfunc(const std::size_t a_idx, const std::uintptr_t a_newFunc)
 			requires(std::same_as<value_type, std::uintptr_t>)
 		{
diff --git a/src/REL/Relocation.cpp b/src/REL/Relocation.cpp
new file mode 100644
index 00000000..beafb6e5
--- /dev/null
+++ b/src/REL/Relocation.cpp
@@ -0,0 +1,32 @@
+#include "REL/Relocation.h"
+
+#ifdef SFSE_SUPPORT_XBYAK
+#	include <xbyak/xbyak.h>
+
+namespace REL
+{
+	struct write_func_impl : Xbyak::CodeGenerator
+	{
+		write_func_impl(std::uintptr_t a_dst)
+		{
+			Xbyak::Label dst;
+			jmp(ptr[rip + dst]);
+			L(dst);
+			dq(a_dst);
+		}
+	};
+
+	template <class T>
+	void Relocation<T>::write_func(const std::size_t a_count, const std::uintptr_t a_dst)
+		requires(std::same_as<value_type, std::uintptr_t>)
+	{
+		safe_fill(address(), INT3, a_count);
+		auto patch = write_func_impl{ a_dst };
+		patch.ready();
+		assert(patch.getSize() <= a_count);
+		safe_write(address(), std::span{ patch.getCode<const std::byte*>(), patch.getSize() });
+	}
+
+	template void Relocation<std::uintptr_t>::write_func(const std::size_t, const std::uintptr_t);
+}
+#endif