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fbcon: Console Rotation - Fix wrong shift calculation

PATCH New Antonino A. Daplas 1 participant 1 message Nov 19, 2005

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PATCH 1/1 fbcon: Console Rotation - Fix wrong shift calculation

The shift value (amount to shift the bitmap so first pixel starts at origin(0,0)) is incorrect. This causes corrupted characters or a kernel crash if fontwidth is not divisible by 8 at 270 degrees, or fontheight not divisible by 8 at 180 degrees.

Report and part of the fix contributed by Knut Petersen.

---

 drivers/video/console/fbcon_rotate.h |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
drivers/video/console/fbcon_rotate.h +2 -2
index 90c6720..e504fbf 100644
@@ -49,7 +49,7 @@ static inline void pattern_set_bit(u32 x
 static inline void rotate_ud(const char *in, char *out, u32 width, u32 height)
 {
 	int i, j;
-	int shift = width % 8;
+	int shift = (8 - (width % 8)) & 7;
 
 	width = (width + 7) & ~7;
 
@@ -85,7 +85,7 @@ static inline void rotate_cw(const char 
 static inline void rotate_ccw(const char *in, char *out, u32 width, u32 height)
 {
 	int i, j, h = height, w = width;
-	int shift = width % 8;
+	int shift = (8 - (width % 8)) & 7;
 
 	width = (width + 7) & ~7;
 	height = (height + 7) & ~7;

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