From 0f045407d9af3baf835ef61c62f031d9877e1840 Mon Sep 17 00:00:00 2001
From: friendlyanon <friendlyanon@users.noreply.github.com>
Date: Wed, 1 May 2024 16:14:31 +0200
Subject: [PATCH] Implement assembly functions using inline `__asm`

This avoids having to rely on MASM.
---
 wrappers/CMakeLists.txt | 11 +++--------
 wrappers/cas.asm        | 17 -----------------
 wrappers/cas.h          | 10 ----------
 wrappers/detect486.asm  | 28 ----------------------------
 wrappers/detect486.c    | 26 ++++++++++++++++++++++++++
 wrappers/detect486.h    |  6 +-----
 wrappers/kernel32.c     | 41 +++++++++++++++++++++++++++--------------
 7 files changed, 57 insertions(+), 82 deletions(-)
 delete mode 100644 wrappers/cas.asm
 delete mode 100644 wrappers/cas.h
 delete mode 100644 wrappers/detect486.asm
 create mode 100644 wrappers/detect486.c

diff --git a/wrappers/CMakeLists.txt b/wrappers/CMakeLists.txt
index 402974c..2fa8548 100644
--- a/wrappers/CMakeLists.txt
+++ b/wrappers/CMakeLists.txt
@@ -1,6 +1,6 @@
 cmake_minimum_required(VERSION 3.13)
 
-project(corkel32 C ASM_MASM)
+project(corkel32 C)
 
 add_compile_definitions(_WIN32_WINNT=0x0400)
 
@@ -12,12 +12,7 @@ target_compile_definitions(corkdebug PRIVATE _CRT_SECURE_NO_WARNINGS=1)
 
 add_library(
   detect486 OBJECT
-  detect486.asm
-)
-
-add_library(
-  cas OBJECT
-  cas.asm
+  detect486.c
 )
 
 include(CheckSymbolExists)
@@ -31,7 +26,7 @@ add_library(
   comdlg32.c
   corkel32.def
 )
-target_link_libraries(corkel32 PRIVATE corkdebug detect486 cas)
+target_link_libraries(corkel32 PRIVATE corkdebug detect486)
 target_compile_definitions(corkel32 PRIVATE _CRT_SECURE_NO_WARNINGS=1)
 
 # NTDLL => CORNT
diff --git a/wrappers/cas.asm b/wrappers/cas.asm
deleted file mode 100644
index 6e95593..0000000
--- a/wrappers/cas.asm
+++ /dev/null
@@ -1,17 +0,0 @@
-.486
-.MODEL FLAT
-
-.CODE
-
-OPTION PROLOGUE:NONE
-OPTION EPILOGUE:NONE
-
-_InterlockedCompareExchange_486@12 PROC
-  mov ecx, DWORD PTR [esp + 4] ; dest
-  mov edx, DWORD PTR [esp + 8] ; exchange
-  mov eax, DWORD PTR [esp + 12] ; compare
-  lock cmpxchg DWORD PTR [ecx], edx
-  ret 12
-_InterlockedCompareExchange_486@12 ENDP
-
-END
diff --git a/wrappers/cas.h b/wrappers/cas.h
deleted file mode 100644
index c2a0ef3..0000000
--- a/wrappers/cas.h
+++ /dev/null
@@ -1,10 +0,0 @@
-#ifndef CAS
-#define CAS
-
-#ifndef STDCALL
-#define STDCALL __stdcall
-#endif
-
-long STDCALL InterlockedCompareExchange_486(long* dest, long exchange, long compare);
-
-#endif // CAS
diff --git a/wrappers/detect486.asm b/wrappers/detect486.asm
deleted file mode 100644
index dbd4686..0000000
--- a/wrappers/detect486.asm
+++ /dev/null
@@ -1,28 +0,0 @@
-.386
-.MODEL FLAT, STDCALL
-
-.CODE
-
-is_cpu_486_or_newer PROC
-  pushfd
-  pop eax
-  mov ebx, eax
-  xor eax, 40000h ; toggle the AC bit in EFLAGS (only available in 486 or newer)
-  push eax
-  popfd
-  pushfd
-  pop eax
-  cmp eax, ebx
-  jz is_386
-  push ebx
-  popfd
-  xor eax, eax
-  inc eax
-  ret
-
-is_386:
-  xor eax, eax
-  ret
-is_cpu_486_or_newer ENDP
-
-END
diff --git a/wrappers/detect486.c b/wrappers/detect486.c
new file mode 100644
index 0000000..9bfe773
--- /dev/null
+++ b/wrappers/detect486.c
@@ -0,0 +1,26 @@
+#include "detect486.h"
+
+__declspec(naked) int is_cpu_486_or_newer(void)
+{
+  __asm {
+    pushfd
+    pop eax
+    mov ebx, eax
+    xor eax, 40000h ; toggle the AC bit in EFLAGS (only available in 486 or newer)
+    push eax
+    popfd
+    pushfd
+    pop eax
+    cmp eax, ebx
+    jz is_386
+    push ebx
+    popfd
+    xor eax, eax
+    inc eax
+    ret
+
+  is_386:
+    xor eax, eax
+    ret
+  }
+}
diff --git a/wrappers/detect486.h b/wrappers/detect486.h
index 2670d23..c5522fe 100644
--- a/wrappers/detect486.h
+++ b/wrappers/detect486.h
@@ -1,10 +1,6 @@
 #ifndef DETECT_486
 #define DETECT_486
 
-#ifndef STDCALL
-#define STDCALL __stdcall
-#endif
-
-int STDCALL is_cpu_486_or_newer(void);
+int is_cpu_486_or_newer(void);
 
 #endif // DETECT_486
diff --git a/wrappers/kernel32.c b/wrappers/kernel32.c
index aa3d271..c1c045a 100644
--- a/wrappers/kernel32.c
+++ b/wrappers/kernel32.c
@@ -1,7 +1,6 @@
 #include <stdio.h>
 #include <windows.h>
 
-#include "cas.h"
 #include "debug.h"
 #include "detect486.h"
 
@@ -155,22 +154,36 @@ BOOL WINAPI CORKEL32_DeviceIoControl(HANDLE hDevice, DWORD dwIoControlCode, LPVO
   return e;
 }
 
+static char const* InterlockedCompareExchange_name = "InterlockedCompareExchange";
+
 // Reimplemented
-LONG WINAPI CORKEL32_InterlockedCompareExchange(LONG* dest, LONG xchg, LONG compare)
+__declspec(naked) LONG WINAPI CORKEL32_InterlockedCompareExchange(LONG* dest, LONG exchange, LONG compare)
 {
-  LONG temp;
-  if (has_cmpxchg) {
-    return InterlockedCompareExchange_486(dest, xchg, compare);
+  __asm {
+    cmp has_cmpxchg, 0
+    jz ICE_is_386
+    mov edx, DWORD PTR [esp + 4] ; dest
+    mov ecx, DWORD PTR [esp + 8] ; exchange
+    mov eax, DWORD PTR [esp + 12] ; compare
+    lock cmpxchg DWORD PTR [edx], ecx
+    ret 12
+
+  ICE_is_386:
+    push InterlockedCompareExchange_name
+    push TRACE_FORCE_DONT_PRINT
+    call Trace
+    add esp, 8
+
+    mov edx, DWORD PTR [esp + 4] ; dest
+    mov eax, DWORD PTR [edx]
+    cmp eax, DWORD PTR [esp + 12] ; compare
+    jne ICE_exit
+    mov ecx, DWORD PTR [esp + 8] ; exchange
+    mov DWORD PTR [edx], ecx
+
+  ICE_exit:
+    ret 12
   }
-
-  temp = *dest;
-  Trace(TRACE_FORCE_DONT_PRINT, "InterlockedCompareExchange");
-
-  if (compare == *dest) {
-    *dest = xchg;
-  }
-
-  return temp;
 }
 
 HANDLE WINAPI CORKEL32_CreateToolhelp32Snapshot(DWORD param_0, DWORD param_1)