nsis: simplify OS detection

extras/package/win32/NSIS/helpers/extensions.nsh

@@ -19,15 +19,9 @@ NoBackup:
   WriteRegStr HKCR "VLC$R0\shell\Open\command" "" '"$INSTDIR\vlc.exe" --started-from-file "%1"'
   WriteRegStr HKCR "VLC$R0\DefaultIcon" "" '"$INSTDIR\vlc.exe",0'
 
-;;; Vista Only part
-  ; Vista and above detection
-  ReadRegStr $R1 HKLM "SOFTWARE\Microsoft\Windows NT\CurrentVersion" CurrentVersion
-  StrCpy $R2 $R1 1
-  StrCmp $R2 '6' ForVista ToEnd
-ForVista:
+  ${If} ${AtLeastWinVista}
     WriteRegStr HKLM "Software\Clients\Media\VLC\Capabilities\FileAssociations" "$R0" "VLC$R0"
-
-ToEnd:
+  ${EndIf}
 FunctionEnd
 
 ;; Function that registers one skin extension for VLC
@@ -46,15 +40,9 @@ NoBackup:
   WriteRegStr HKCR "VLC$R0\shell\Open\command" "" '"$INSTDIR\vlc.exe" -Iskins --skins2-last "%1"'
   WriteRegStr HKCR "VLC$R0\DefaultIcon" "" '"$INSTDIR\vlc.exe",0'
 
-;;; Vista Only part
-  ; Vista and above detection
-  ReadRegStr $R1 HKLM "SOFTWARE\Microsoft\Windows NT\CurrentVersion" CurrentVersion
-  StrCpy $R2 $R1 1
-  StrCmp $R2 '6' ForVista ToEnd
-ForVista:
+  ${If} ${AtLeastWinVista}
     WriteRegStr HKLM "Software\Clients\Media\VLC\Capabilities\FileAssociations" "$R0" "VLC$R0"
-
-ToEnd:
+  ${EndIf}
 FunctionEnd
 
 ;; Function that removes one extension that VLC owns.

extras/package/win32/NSIS/vlc.win32.nsi.in

@@ -215,13 +215,9 @@ ${MementoSection} $Name_Section01 SEC01
   WriteRegStr HKCR Applications\vlc.exe\shell\Open\command "" '"$INSTDIR\vlc.exe" --started-from-file "%1"'
   !insertmacro MacroAllExtensions WriteRegStrSupportedTypes
 
-; Windows default programs Registration
+  ; Windows default programs Registration
   ; Vista and above detection
-  ReadRegStr $R0 HKLM "SOFTWARE\Microsoft\Windows NT\CurrentVersion" CurrentVersion
-  StrCpy $R1 $R0 1
-  StrCmp $R1 '6' lbl_vista lbl_done
-
-  lbl_vista:
+  ${If} ${AtLeastWinVista}
     WriteRegStr HKLM "Software\RegisteredApplications" "VLC" "Software\Clients\Media\VLC\Capabilities"
     WriteRegStr HKLM "Software\Clients\Media\VLC\Capabilities" "ApplicationName" "VLC media player"
     WriteRegStr HKLM "Software\Clients\Media\VLC\Capabilities" "ApplicationDescription" "VLC - The video swiss knife"
@@ -230,8 +226,7 @@ ${MementoSection} $Name_Section01 SEC01
     WriteRegStr HKLM "Software\Clients\Media\VLC\InstallInfo" "ShowIconsCommand" "$\"$INSTDIR\spad-setup.exe$\" /ShowIcons /S"
     WriteRegStr HKLM "Software\Clients\Media\VLC\InstallInfo" "ReinstallCommand" "$\"$INSTDIR\spad-setup.exe$\" /Reinstall /S"
     WriteRegDWORD HKLM "Software\Clients\Media\VLC\InstallInfo" "IconsVisible" 0x001
-
-  lbl_done:
+  ${EndIf}
 ${MementoSectionEnd}
 
 ${MementoSection} $Name_Section02a SEC02a