4 files changed, 10 insertions, 12 deletions
diff --git a/board-js2x/slof/helper.fs b/board-js2x/slof/helper.fs
index 918fdc4..6030330 100644
--- a/board-js2x/slof/helper.fs
+++ b/board-js2x/slof/helper.fs
@@ -30,3 +30,7 @@
 : invert-region ( addr len -- )
    0 ?DO dup dup rb@ -1 xor swap rb! 1+ LOOP drop
 ;
+
+: invert-region-x ( addr len -- )
+   /x / 0 ?DO dup dup rx@ -1 xor swap rx! xa1+ LOOP drop
+;
diff --git a/board-qemu/slof/helper.fs b/board-qemu/slof/helper.fs
index da676c7..c807bc6 100644
--- a/board-qemu/slof/helper.fs
+++ b/board-qemu/slof/helper.fs
@@ -36,3 +36,7 @@
 : invert-region ( addr len -- )
    over swap 0 swap 1 hv-logical-memop drop
 ;
+
+: invert-region-x ( addr len -- )
+   over swap /x / 3 swap 1 hv-logical-memop drop
+;
diff --git a/board-qemu/slof/pci-device_1234_1111.fs b/board-qemu/slof/pci-device_1234_1111.fs
index a5c3584..26b0623 100644
--- a/board-qemu/slof/pci-device_1234_1111.fs
+++ b/board-qemu/slof/pci-device_1234_1111.fs
@@ -188,16 +188,9 @@ a CONSTANT VBE_DISPI_INDEX_NB
 : display-remove ( -- ) 
 ;
 
-: hcall-invert-screen ( -- )
-    frame-buffer-adr frame-buffer-adr 3
-    screen-height screen-width * screen-depth * /x /
-    1 hv-logical-memop
-    drop
-;
-
 : hcall-blink-screen ( -- )
     \ 32 msec delay for visually noticing the blink
-    hcall-invert-screen 20 ms hcall-invert-screen
+    invert-screen 20 ms invert-screen
 ;
 
 : display-install ( -- )
@@ -211,7 +204,6 @@ a CONSTANT VBE_DISPI_INDEX_NB
         disp-width char-width / disp-height char-height /
         disp-depth 7 + 8 /                      ( width height #lines #cols depth )
         fb-install
-	['] hcall-invert-screen to invert-screen
 	['] hcall-blink-screen to blink-screen
          true to is-installed?
     THEN
diff --git a/slof/fs/fbuffer.fs b/slof/fs/fbuffer.fs
index deeba6b..fcdd2fa 100644
--- a/slof/fs/fbuffer.fs
+++ b/slof/fs/fbuffer.fs
@@ -170,9 +170,7 @@ CREATE bitmap-buffer 400 4 * allot
 ;
 
 : fb8-invert-screen ( -- )
-	frame-buffer-adr screen-height screen-width * screen-depth * 2dup /x / 0 ?DO
-		dup rx@ -1 xor over rx! xa1+
-	LOOP 3drop
+	frame-buffer-adr screen-height screen-width * screen-depth * invert-region-x
 ;
 
 : fb8-blink-screen ( -- ) fb8-invert-screen fb8-invert-screen ;