From 2ddab09733fe96aeb603fb9459f7c3df846ad82e Mon Sep 17 00:00:00 2001
From: Delphi-FPC-Lazarus <support@peter-ebe.de>
Date: Thu, 24 Sep 2020 13:22:14 +0200
Subject: [PATCH] fastpatch working with delphi xe10 (32/64 Bit)

inspired by https://stackoverflow.com/questions/7581321/how-to-make-fastcodepatch-work-in-delphi-xe2-win64-platform/7581606
---
 FastcodePatch.pas | 28 +++++++++++++++++-----------
 1 file changed, 17 insertions(+), 11 deletions(-)

diff --git a/FastcodePatch.pas b/FastcodePatch.pas
index 3e112af..1280105 100644
--- a/FastcodePatch.pas
+++ b/FastcodePatch.pas
@@ -27,7 +27,7 @@
 
 interface
 
-function FastcodeGetAddress(AStub: Pointer): Pointer;
+function FastcodeGetAddress(AProc: Pointer): Pointer;
 procedure FastcodeAddressPatch(const ASource, ADestination: Pointer);
 
 implementation
@@ -39,18 +39,24 @@ implementation
   PJump = ^TJump;
   TJump = packed record
     OpCode: Byte;
-    Distance: Pointer;
+    Distance: integer;
   end;
 
-function FastcodeGetAddress(AStub: Pointer): Pointer;
+function FastcodeGetAddress(AProc: Pointer): Pointer;
+type
+  PAbsoluteIndirectJmp = ^TAbsoluteIndirectJmp;
+  TAbsoluteIndirectJmp = packed record
+    OpCode: Word;   //$FF25(Jmp, FF /4)
+    Addr: Cardinal;
+  end;
+var J: PAbsoluteIndirectJmp;
 begin
-  if PBYTE(AStub)^ = $E8 then
-  begin
-    Inc(Integer(AStub));
-    Result := Pointer(Integer(AStub) + SizeOf(Pointer) + PInteger(AStub)^);
-  end
+  J := PAbsoluteIndirectJmp(AProc);
+  if (J.OpCode = $25FF) then
+    {$ifdef Win32}Result := PPointer(J.Addr)^{$endif}
+    {$ifdef Win64}Result := PPointer(NativeUInt(AProc) + J.Addr + 6{Instruction Size})^{$endif}
   else
-    Result := nil;
+    Result := AProc;
 end;
 
 procedure FastcodeAddressPatch(const ASource, ADestination: Pointer);
@@ -64,11 +70,11 @@ procedure FastcodeAddressPatch(const ASource, ADestination: Pointer);
   begin
     NewJump := PJump(ASource);
     NewJump.OpCode := $E9;
-    NewJump.Distance := Pointer(Integer(ADestination) - Integer(ASource) - 5);
+    NewJump.Distance := NativeUInt(ADestination) - NativeUInt(ASource) - Size;
 
     FlushInstructionCache(GetCurrentProcess, ASource, SizeOf(TJump));
     VirtualProtect(ASource, Size, OldProtect, @OldProtect);
   end;
 end;
 
-end.
+end.
\ No newline at end of file