Fully decompile xapi0

Incidental changes include fixes for Xapi in the Makefille and
objdiff.json, as well as new compiler flags for Xapi.

decompile/Makefile

@@ -3,7 +3,7 @@
 
 # All object files to link together
 OBJ = src/JSRF/Jet2.obj src/JSRF/Core.obj src/JSRF/GameData.obj\
-      src/XDK/CRT/CRT0.obj
+      src/XDK/Xapi/xapi0.obj
 
 # Import library for the only thing we don't compile ourselves, the Xbox kernel
 LIB = lib/xboxkrnl.lib
@@ -14,7 +14,7 @@ all: $(OBJ) # For now, just compile all the object files
 
 
 ## Build commands
-.SUFFIXES: .cpp .obj .def .lib .exe.xbe
+.SUFFIXES: .c .cpp .obj .def .lib .exe.xbe
 
 # Convert compiled executable into a working Xbox executable
 # (TODO: we may want to fork cxbe to add section checksums and the game ID)
@@ -32,7 +32,7 @@ src/JSRF/Jet2.exe: $(OBJ) $(LIB)
 
 # Compile object files from source
 .c.obj:
-	CL.EXE /nologo /Wall /W4 /Ogityb0 /GfX /Fo$@ /c $<
+	CL.EXE /nologo /Wall /W4 /O1giy /Fo$@ /c $<
 .cpp.obj:
 	CL.EXE /nologo /Wall /W4 /Ogityb0 /GfX /Fo$@ /c $<
 
@@ -41,9 +41,9 @@ src/JSRF/Jet2.exe: $(OBJ) $(LIB)
 src/JSRF/Jet2.obj: src/JSRF/Core.hpp src/XDK/CRT/stddef.h src/XDK/D3D.h\
                    src/XDK/Win32.h
 
-src/JSRF/Core.obj: src/JSRF/Core.hpp src/Smilebit/MMatrix.hpp\
+src/JSRF/Core.obj: src/JSRF/Core.hpp src/MUSASHI/MMatrix.hpp\
                    src/XDK/CRT/stddef.h src/XDK/D3D.h src/XDK/Win32.h
 
 src/JSRF/GameData.obj: src/JSRF/GameData.hpp
 
-src/XDK/CRT/CRT0.obj: src/XDK/Win32.h
+src/XDK/Xapi/xapi0.obj: src/XDK/Win32.h

decompile/objdiff.json

@@ -1,6 +1,8 @@
 {
   "custom_make": "NMAKE.EXE",
   "watch_patterns": [
+    "*.c",
+    "*.h",
     "*.cpp",
     "*.hpp"
   ],
@@ -48,7 +50,7 @@
       "target_path": "target/XDK/Xapi/xapi0.obj",
       "base_path": "src/XDK/Xapi/xapi0.obj",
       "metadata": {
-        "complete": false,
+        "complete": true,
         "source_path": "src/XDK/Xapi/xapi0.c"
       }
     }

decompile/src/JSRF/Core.hpp

@@ -5,7 +5,7 @@ Game and GameObj classes that form the foundation of the JSRF game code.
 #ifndef CORE_HPP
 #define CORE_HPP
 
-#include "../Smilebit/MMatrix.hpp"
+#include "../MUSASHI/MMatrix.hpp"
 #include "../XDK/CRT/stddef.h"
 #include "../XDK/D3D.h"
 #include "../XDK/Win32.h"

decompile/src/XDK/Xapi/xapi0.c

@@ -21,11 +21,14 @@ extern struct IMAGE_TLS_DIRECTORY {
 	DWORD   SizeOfZeroFill;
 	DWORD   Characteristics;
 } _tls_used;
+extern int _tls_array;
+extern int _tls_index;
 
 extern int XapiTlsSize;
 
 DWORD __stdcall mainXapiStartup(LPVOID lpThreadParameter);
-BOOL  __stdcall CloseHandle    (HANDLE hHandle          );
+void  __stdcall XapiInitProcess(void);
+BOOL  __stdcall CloseHandle    (HANDLE hHandle);
 
 typedef DWORD (__stdcall * LPTHREAD_START_ROUTINE)(LPVOID lpThreadParameter);
 HANDLE __stdcall CreateThread(
@@ -43,22 +46,106 @@ void __stdcall XapiBootToDash(
 	DWORD dwParameter2
 );
 
+void __stdcall _rtinit(void);
+void __stdcall _cinit (void);
+
 
 // Every program is supposed to have a main(), so we can just assume its
-// existence with a declaration here
-int main(void);
+// existence with a declaration here.  Interestingly, it's called with
+// arguments here despite being declared without any on the developer's side.
+int main(
+	int      argc,
+	char * * argv,
+	char * * envp
+);
 
 
 // Address: 0x00147FB4
-// Status: unimplemented
-DWORD __stdcall mainXapiStartup(LPVOID lpThreadParameter) {
-/* Runs some Xbox-specific initialization and then calls main() */
-	main();
-	return 0;
+// Status: matching
+__declspec(naked) DWORD __stdcall mainXapiStartup(LPVOID lpThreadParameter) {
+/* Runs some Xbox-specific initialization and then calls main()
+It appears to be truly impossible in Visual C++ 7.0 to access the FS register
+without writing assembly, and also for inline assembly to write to a variable
+in a register rather than on the stack.  Thus, the only apparent way to make
+the middle part of the function match is through writing the instructions
+directly.  Given that the C parts of this function are so simple that a human
+and a compiler would reasonably produce the exact same code, and this function
+exhibits other oddities mentioned in the body, it's likely this whole function
+was originally written purely in assemblys.  In the spirit of decompilation,
+however, we'll lift what we can into C.
+*/
+	XapiInitProcess();
+
+	// Honestly unsure what's being done here, as FS doesn't seem to follow
+	// the same structure as 32-bit Windows
+	__asm {
+		mov  eax, fs:[0x20]
+		mov  eax, [eax+0x250]
+		test eax, eax
+		je   zero
+		mov  ecx, [eax+0x24]
+		jmp  store
+
+		/*
+		All this jumping around is strange, as it could easily be a
+		single branch, which is very plain to see if written out as C
+		(in fact, while MSVC's behaviour hasn't been tested, it
+		wouldn't take a very smart compiler to optimize this out if it
+		was written this way in C).  It seems likely this is awkward
+		human-written assembly.
+		*/
+	zero:
+		xor  ecx, ecx
+
+	store:
+		test ecx, ecx
+		je   end
+
+		/*
+		This section is suspect because of how it preserves edi despite
+		it not being used anywhere else, as if it was a separately
+		written function.  If it was a function, it must have been
+		inlined, but it couldn't be because it must be called from
+		assembly to use the value in ecx that never went on the stack
+		(as passing data from C to assembly has to do).  Notably, this
+		function's calling convention does require edi to be preserved,
+		but if left up to the compiler, it will push and pop edi in the
+		prologue and epilogue, not here (which this function must be
+		declared as naked to avoid).
+
+		It may be that this function was originally written entirely in
+		assembly and declared naked, with the author deciding to
+		preserve edi only in this one section using it.
+		*/
+		push edi
+		mov  eax, fs:[0x28]
+		mov  edi, fs:[_tls_array]
+		mov  edx, [_tls_index]
+		mov  edx, [edi + edx*0x4]
+		sub  edx, [eax + 0x28]
+		mov  byte ptr [ecx], 0x1
+		add  edx, _tls_array
+		mov  [ecx + 0x4], edx
+		pop  edi
+
+	end:
+	};
+
+	_rtinit();
+	_cinit();
+	main(0, NULL, NULL);
+
+	XapiBootToDash(XLD_LAUNCH_DASHBOARD_ERROR, XLD_ERROR_INVALID_XBE, 0);
+
+	// Return 0 to satisfy signature required for thread functions
+	_asm {
+		xor eax, eax
+		ret 4
+	};
 }
 
 // Address: 0x00148023
-// Status: nonmatching
+// Status: matching
 void mainCRTStartup(void) {
 /* The true entrypoint of the game, spawning a thread for the rest to run in
 The linker automatically sets this function to the entrypoint.
@@ -66,11 +153,11 @@ The linker automatically sets this function to the entrypoint.
 	HANDLE thread;
 
 	// Figure out available thread-local storage
-	XapiTlsSize = (
+	XapiTlsSize = 4 + ((
 		(_tls_used.EndAddressOfRawData - _tls_used.StartAddressOfRawData) +
 		_tls_used.SizeOfZeroFill
-	) + 15 & 0xFFFFFFF0; // Round up to nearest 0x10
-	*_tls_used.AddressOfIndex = XapiTlsSize / (-4);
+	) + 15 & 0xFFFFFFF0); // Round up to nearest 0x10
+	*_tls_used.AddressOfIndex = -1 * XapiTlsSize/4;
 
 	// Launch program as a thread
 	thread = CreateThread(NULL, 0, mainXapiStartup, NULL, 0, NULL);

ghidra/make_header.sh

@@ -11,7 +11,7 @@ HEADERS="
 	Std.hpp
 	XDK/Win32.h
 	XDK/D3D.h
-	Smilebit/MMatrix.hpp
+	MUSASHI/MMatrix.hpp
 	JSRF/Core.hpp
 	JSRF/GameData.hpp
 "

ghidra/objects.csv

@@ -5,12 +5,12 @@ JSRF/Jet2.obj,true,0x0006F9E0-0x0006FA6F,,,0x00187710-0x00187724,,,,,,,0x001E620
 ADX (need to decompose),false,0x0013A570-0x0014555F,?,?,?,?,,,,,,?,?,?,
 Xapi (need to decompose),false,0x00145560-0x0014B79F,?,?,?,?,,,,,,?,?,?,
 XDK/Xapi/xapi0.obj,true,0x00147FB4-0x0014807C,,,,,,,,,,,,,
-Smilebit libs (need to decompose),false,0x0014B7A0-0x0017BF3F,?,?,?,?,,,,,,?,?,?-0x0022ED2B,
+Smilebit MUSASHI libs (need to decompose),false,0x0014B7A0-0x0017BF3F,?,?,?,?,,,,,,?,?,?-0x0022ED2B,
 C runtime (need to decompose),false,0x0017BF40-0x00182B80,?,?,?,,,,,?,?,0x0022ED2C-?,?,?,
 Unknown MS math lib,false,0x00182B81-0x0018694F,?,?,?,,,,,?,?,?,?,?,
 Another (tiny) Smilebit math lib,false,0x00186950-0x00186B7F,?,?,?,,,,,?,?,?,?,?,
 Direct3D8 (need to decompose),false,,?,,0x0018CB40-0x0019E334,,,,,?,?,?,?,?,
 DirectSound8 (need to decompose),false,,?,?,,,0x0019E340-0x001BA89B,,,,?,?,?,?,0x0027E080-0x00284E17
-Smilebit/MMatrix.obj,false,,?,,,,0x001BA8A0-0x001BBAAF,,,,,?,?,0x00264BD8-0x00264C13,
+MUSASHI/MMatrix.obj,false,,?,,,,0x001BA8A0-0x001BBAAF,,,,,?,?,0x00264BD8-0x00264C13,
 Xgraphics (need to decompose),false,,?,,,,,0x001BBAC0-0x001BC7BB,,,,?,?,,
 XDK Peripherals (need to decompose),false,,?,,,,,,0x001BC7C0-0x001C3F57,,,?,?,,

readme.md

@@ -3,8 +3,8 @@ A matching decompilation of the Xbox game Jet Set Radio Future.
 
 ## Progress
 - Delinking progress: 1.03% (26559 out of 2574172 bytes in XBE address space)
-- Decompilation progress: 18.5% (31 out of the 168 functions delinked so far)
-- **Estimated total progress: 0.19%** (previous two multiplied together)
+- Decompilation progress: 19.6% (33 out of the 168 functions delinked so far)
+- **Estimated total progress: 0.20%** (previous two multiplied together)
 
 ## Roadmap
 The approach of this decompilation is to: