lkml.org 
[lkml]   [2002]   [Aug]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Date
Subject[PATCH] fix endian problems in cfb_imageblit
The cfb_imageblit() function in drivers/video/cfbimgblt.c is broken on
big-endian machines. Using test_bit on the font data is a really bad
idea. First, on big-endian machines it doesn't test the bit you
expect, and secondly, many architectures require the pointer argument
to be 4-byte or 8-byte aligned. Finally, the loop was always doing
the pixels right-to-left within a 32-bit word, which is wrong on
big-endian machines.

Here is a patch that fixes these problems.

Paul.

diff -urN linux-2.5/drivers/video/cfbimgblt.c pmac-2.5/drivers/video/cfbimgblt.c
--- linux-2.5/drivers/video/cfbimgblt.c Mon Jun 10 03:39:17 2002
+++ pmac-2.5/drivers/video/cfbimgblt.c Sat Aug 17 21:15:26 2002
@@ -41,11 +41,21 @@
#define DPRINTK(fmt, args...)
#endif

+#ifdef __BIG_ENDIAN
+#define LEFT_POS(bpp) (BITS_PER_LONG - bpp)
+#define NEXT_POS(pos, bpp) ((pos) -= (bpp))
+#else
+#define LEFT_POS(bpp) (0)
+#define NEXT_POS(pos, bpp) ((pos) += (bpp))
+#endif
+
void cfb_imageblit(struct fb_info *p, struct fb_image *image)
{
int pad, ppw;
int x2, y2, n, i, j, k, l = 7;
- unsigned long tmp = ~0 << (BITS_PER_LONG - p->var.bits_per_pixel);
+ int bpp = p->var.bits_per_pixel;
+ int ppos;
+ unsigned long tmp = (1 << bpp) - 1;
unsigned long fgx, bgx, fgcolor, bgcolor, eorx;
unsigned long end_mask;
unsigned long *dst = NULL;
@@ -66,11 +76,11 @@
image->height = y2 - image->dy;

dst1 = p->screen_base + image->dy * p->fix.line_length +
- ((image->dx * p->var.bits_per_pixel) >> 3);
+ ((image->dx * bpp) >> 3);

- ppw = BITS_PER_LONG/p->var.bits_per_pixel;
+ ppw = BITS_PER_LONG / bpp;

- src = image->data;
+ src = image->data;

if (image->depth == 1) {

@@ -83,8 +93,8 @@
}

for (i = 0; i < ppw-1; i++) {
- fgx <<= p->var.bits_per_pixel;
- bgx <<= p->var.bits_per_pixel;
+ fgx <<= bpp;
+ bgx <<= bpp;
fgx |= fgcolor;
bgx |= bgcolor;
}
@@ -98,10 +108,12 @@

for (j = image->width/ppw; j > 0; j--) {
end_mask = 0;
-
+ ppos = LEFT_POS(bpp);
+
for (k = ppw; k > 0; k--) {
- if (test_bit(l, (unsigned long *) src))
- end_mask |= (tmp >> (p->var.bits_per_pixel*(k-1)));
+ if (*src & (1 << l))
+ end_mask |= tmp << ppos;
+ NEXT_POS(ppos, bpp);
l--;
if (l < 0) { l = 7; src++; }
}
@@ -110,10 +122,12 @@
}

if (n) {
- end_mask = 0;
+ end_mask = 0;
+ ppos = LEFT_POS(bpp);
for (j = n; j > 0; j--) {
- if (test_bit(l, (unsigned long *) src))
- end_mask |= (tmp >> (p->var.bits_per_pixel*(j-1)));
+ if (*src & (1 << l))
+ end_mask |= tmp << ppos;
+ NEXT_POS(ppos, bpp);
l--;
if (l < 0) { l = 7; src++; }
}
@@ -125,7 +139,7 @@
}
} else {
/* Draw the penguin */
- n = ((image->width * p->var.bits_per_pixel) >> 3);
+ n = ((image->width * bpp) >> 3);
end_mask = 0;
}
}
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
\
 
 \ /
  Last update: 2005-03-22 13:28    [W:0.028 / U:2.436 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site