Delink/begin decompiling entry point

That is, xapi0.obj, which has been renamed from crt0.obj because it
appears to be part of the Xbox libraries rather than the C runtime.

decompile/src/XDK/Xapi/xapi0.c

@@ -0,0 +1,83 @@
+/* JSRF Decompilation: XDK/Xapi/xapi0.c
+Entrypoint for Xbox programs.
+Awkwardly, the placement in the .xbe suggests this is not part of the C runtime
+(which is normally what provides mainCRTStartup()), but rather part of Xapi.
+It's been named xapi0 in analogy to crt0 in a C runtime.
+*/
+
+#include "../CRT/stddef.h"
+#include "../Win32.h"
+
+
+// Things that should get declared in a header somewhere
+#define XLD_LAUNCH_DASHBOARD_ERROR 1
+#define XLD_ERROR_INVALID_XBE      1
+
+extern struct IMAGE_TLS_DIRECTORY {
+	DWORD   StartAddressOfRawData;
+	DWORD   EndAddressOfRawData;
+	DWORD * AddressOfIndex;
+	void  * AddressOfCallbacks;
+	DWORD   SizeOfZeroFill;
+	DWORD   Characteristics;
+} _tls_used;
+
+extern int XapiTlsSize;
+
+DWORD __stdcall mainXapiStartup(LPVOID lpThreadParameter);
+BOOL  __stdcall CloseHandle    (HANDLE hHandle          );
+
+typedef DWORD (__stdcall * LPTHREAD_START_ROUTINE)(LPVOID lpThreadParameter);
+HANDLE __stdcall CreateThread(
+	void *                 lpThreadAttributes,
+	DWORD                  dwStackSize,
+	LPTHREAD_START_ROUTINE lpStartAddress,
+	LPVOID                 lpParameter,
+	DWORD                  dwCreationFlags,
+	PDWORD                 lpThreadId
+);
+
+void __stdcall XapiBootToDash(
+	DWORD dwReason,
+	DWORD dwParameter1,
+	DWORD dwParameter2
+);
+
+
+// Every program is supposed to have a main(), so we can just assume its
+// existence with a declaration here
+int main(void);
+
+
+// Address: 0x00147FB4
+// Status: unimplemented
+DWORD __stdcall mainXapiStartup(LPVOID lpThreadParameter) {
+/* Runs some Xbox-specific initialization and then calls main() */
+	main();
+	return 0;
+}
+
+// Address: 0x00148023
+// Status: nonmatching
+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.
+*/
+	HANDLE thread;
+
+	// Figure out available thread-local storage
+	XapiTlsSize = (
+		(_tls_used.EndAddressOfRawData - _tls_used.StartAddressOfRawData) +
+		_tls_used.SizeOfZeroFill
+	) + 15 & 0xFFFFFFF0; // Round up to nearest 0x10
+	*_tls_used.AddressOfIndex = XapiTlsSize / (-4);
+
+	// Launch program as a thread
+	thread = CreateThread(NULL, 0, mainXapiStartup, NULL, 0, NULL);
+
+	// Boot back to dashboard with an error message if launching failed
+	if (thread == NULL)
+		XapiBootToDash(XLD_LAUNCH_DASHBOARD_ERROR, XLD_ERROR_INVALID_XBE, 0);
+
+	CloseHandle(thread);
+}