fbdev: Support for byte-reversed framebuffer formats

Allow generic frame-buffer code to correctly write texts and blit images for
1, 2 and 4 bit per pixel frame-buffer organizations when pixels in bytes are
organized to in opposite order than bytes in long type.

Overhead should be reasonable.  If option is not selected, than compiler
should eliminate completely all overhead.

The feature is disabled at compile time if CONFIG_FB_CFB_REV_PIXELS_IN_BYTE is
not set.

[adaplas]
Convert helper functions to macros if feature is not enabled.

Signed-off-by: Pavel Pisa <pisa@cmp.felk.cvut.cz>
Signed-off-by: Antonino Daplas <adaplas@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 10 insertions, 7 deletions

diff --git a/drivers/video/cfbimgblt.c b/drivers/video/cfbimgblt.c
index 261004473c8e..f598907b42ad 100644
--- a/drivers/video/cfbimgblt.c
+++ b/drivers/video/cfbimgblt.c
@@ -33,6 +33,7 @@
 #include <linux/string.h>
 #include <linux/fb.h>
 #include <asm/types.h>
+#include "fb_draw.h"
 
 #define DEBUG
 
@@ -87,6 +88,7 @@ static inline void color_imageblit(const struct fb_image *image,
         u32 null_bits = 32 - bpp;
         u32 *palette = (u32 *) p->pseudo_palette;
         const u8 *src = image->data;
+        u32 bswapmask = fb_compute_bswapmask(p);
 
         dst2 = (u32 __iomem *) dst1;
         for (i = image->height; i--; ) {
@@ -96,7 +98,7 @@ static inline void color_imageblit(const struct fb_image *image,
                 val = 0;
                 
                 if (start_index) {
-                        u32 start_mask = ~(FB_SHIFT_HIGH(~(u32)0, start_index));
+                        u32 start_mask = ~fb_shifted_pixels_mask_u32(start_index, bswapmask);
                         val = FB_READL(dst) & start_mask;
                         shift = start_index;
                 }
@@ -107,7 +109,7 @@ static inline void color_imageblit(const struct fb_image *image,
                         else
                                 color = *src;
                         color <<= FB_LEFT_POS(bpp);
-                        val |= FB_SHIFT_HIGH(color, shift);
+                        val |= FB_SHIFT_HIGH(color, shift ^ bswapmask);
                         if (shift >= null_bits) {
                                 FB_WRITEL(val, dst++);
         
@@ -119,7 +121,7 @@ static inline void color_imageblit(const struct fb_image *image,
                         src++;
                 }
                 if (shift) {
-                        u32 end_mask = FB_SHIFT_HIGH(~(u32)0, shift);
+                        u32 end_mask = fb_shifted_pixels_mask_u32(shift, bswapmask);
 
                         FB_WRITEL((FB_READL(dst) & end_mask) | val, dst);
                 }
@@ -147,7 +149,8 @@ static inline void slow_imageblit(const struct fb_image *image, struct fb_info *
         u32 spitch = (image->width+7)/8;
         const u8 *src = image->data, *s;
         u32 i, j, l;
-        
+        u32 bswapmask = fb_compute_bswapmask(p);
+
         dst2 = (u32 __iomem *) dst1;
         fgcolor <<= FB_LEFT_POS(bpp);
         bgcolor <<= FB_LEFT_POS(bpp);
@@ -161,7 +164,7 @@ static inline void slow_imageblit(const struct fb_image *image, struct fb_info *
 
                 /* write leading bits */
                 if (start_index) {
-                        u32 start_mask = ~(FB_SHIFT_HIGH(~(u32)0,start_index));
+                        u32 start_mask = ~fb_shifted_pixels_mask_u32(start_index, bswapmask);
                         val = FB_READL(dst) & start_mask;
                         shift = start_index;
                 }
@@ -169,7 +172,7 @@ static inline void slow_imageblit(const struct fb_image *image, struct fb_info *
                 while (j--) {
                         l--;
                         color = (*s & (1 << l)) ? fgcolor : bgcolor;
-                        val |= FB_SHIFT_HIGH(color, shift);
+                        val |= FB_SHIFT_HIGH(color, shift ^ bswapmask);
                         
                         /* Did the bitshift spill bits to the next long? */
                         if (shift >= null_bits) {
@@ -184,7 +187,7 @@ static inline void slow_imageblit(const struct fb_image *image, struct fb_info *
 
                 /* write trailing bits */
                 if (shift) {
-                        u32 end_mask = FB_SHIFT_HIGH(~(u32)0, shift);
+                        u32 end_mask = fb_shifted_pixels_mask_u32(shift, bswapmask);
 
                         FB_WRITEL((FB_READL(dst) & end_mask) | val, dst);
                 }