【バグ】WideCharToMultiByte の動作がOSごとに違う！その２

int APIENTRY _tWinMain(HINSTANCE hInstance,
                     HINSTANCE hPrevInstance,
                     LPTSTR    lpCmdLine,
                     int       nCmdShow)
{
//  50220   |JIS
//  50221   |JIS(Allow 1 byte Kana)
//  50222   |JIS(Allow 1 byte Kana)(SO/SI)
  int cp;
  HINSTANCE hDll=LoadLibraryA("NTDLL.dll");
  FARPROC bxx=GetProcAddress(hDll,"RtlUnicodeToMultiByteSize");
  char uni[256]="W\x00i\x00n\x00\x12\xff\x2b\xff\x00\x00",str[512],str2[512];
//Win２Ｋ
  char uni2[256]="\x0a\xff\x73\xff\x68\xff\x9d\xff\x32\x00\x6b\x00\x00\x00";
//＊ｳｨﾝ2k
  int r0,r1,r2,r3,r4,r5,r6,r7;
  OSVERSIONINFO OS;
  OS.dwOSVersionInfoSize=sizeof(OS);
  GetVersionEx(&OS);
  cp = 50222;
  r0= WideCharToMultiByte(cp, 0, (wchar_t*)uni, 5, NULL, 0, NULL, NULL);
  r1= WideCharToMultiByte(cp, 0, (wchar_t*)uni, 5, str2, 256, NULL, NULL);
  r2= WideCharToMultiByte(cp, 0, (wchar_t*)uni, 6, NULL, 0, NULL, NULL);
  r3= WideCharToMultiByte(cp, 0, (wchar_t*)uni, 6, str2, 256, NULL, NULL);
  _asm{
      push 0x5*2
      lea eax,uni
      push eax
      lea eax,r4
      push eax
      call bxx 
  }
  _asm{
      push 0x6*2
      lea eax,uni
      push eax
      lea eax,r5
      push eax
      call bxx 
  }

  wsprintfA(str,"OS: %d.%d(Build:%d)\r\n"
               "ExNull 1:%d 2:%d 3:%d\r\n"
               "IncNull 4:%d 5:%d 6:%d\r\n",
          OS.dwMajorVersion,OS.dwMinorVersion,OS.dwBuildNumber,
          r0,r1,r4,r2,r3,r5);
  cp = 50221;
  r0 = WideCharToMultiByte(cp, 0, (wchar_t*)uni2, 6, NULL, 0, NULL, NULL);
  r2 = WideCharToMultiByte(cp, 0, (wchar_t*)uni2, 6, str2, 256, NULL, NULL);
  cp = 50220;
  r4 = WideCharToMultiByte(cp, 0, (wchar_t*)uni2, 6, NULL, 0, NULL, NULL);
  r6 = WideCharToMultiByte(cp, 0, (wchar_t*)uni2, 6, str2, 256, NULL, NULL);

  cp = 50221;
  r1 = WideCharToMultiByte(cp, 0, (wchar_t*)uni2, 7, NULL, 0, NULL, NULL);
  r3 = WideCharToMultiByte(cp, 0, (wchar_t*)uni2, 7, str2, 256, NULL, NULL);
  cp = 50220;
  r5 = WideCharToMultiByte(cp, 0, (wchar_t*)uni2, 7, NULL, 0, NULL, NULL);
  r7 = WideCharToMultiByte(cp, 0, (wchar_t*)uni2, 7, str2, 256, NULL, NULL);
     
  wsprintfA(str+lstrlenA(str),"ExNull2 7:%d 8:%d 9:%d 10:%d\r\n"
        "IncNull2 11:%d 12:%d 13:%d 14:%d",r0,r2,r4,r6,r1,r3,r5,r7);
  MessageBoxA(0,str,"Result",0);
  return 0;
}