[PATCH] fix endian problems in cfb_imageblit
DORMANTno replies
From: Paul Mackerras <hidden>
Date: 2002-08-20 01:33:08
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; } } -------------------------------------------------------
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