[FB PATCH] cfbimgblt isn't 64-bit clean

[FB PATCH] cfbimgblt isn't 64-bit clean

[Richard Henderson]

The text is written as if it's thinking about handling 64-bit
unsigned long, but it doesn't.  The tables that map bits to
pixels are completely unprepared for this.

I thought about widening the tables, but I thought they'd get
unreasonably large.  There's no reason not to go ahead and 
handle this 32-bits at a time.

I've isolated this choice to two defines at the top of the 
file, WORD and BITS_PER_WORD, so it'll not be _that_ hard to
change if someone disagrees.


r~




You can import this changeset into BK by piping this whole message to:
'| bk receive [path to repository]' or apply the patch as usual.

===================================================================


ChangeSet@1.958, 2002-12-27 15:12:24-08:00, rth@are.twiddle.net
  [FB] Use u32 instead of unsigned long for cfbimgblt bit ops.
  The code that maps bits to pixels is not prepared to handle
  a 64-bit long.


 cfbimgblt.c |   94 +++++++++++++++++++++++++++++++-----------------------------
 1 files changed, 49 insertions, 45 deletions


diff -Nru a/drivers/video/cfbimgblt.c b/drivers/video/cfbimgblt.c
--- a/drivers/video/cfbimgblt.c	Fri Dec 27 15:16:03 2002
+++ b/drivers/video/cfbimgblt.c	Fri Dec 27 15:16:03 2002
@@ -21,13 +21,13 @@
  *
  *  FIXME
  *  The code for 24 bit is horrible. It copies byte by byte size instead of
- *  longs like the other sizes. Needs to be optimized.
+ *  words like the other sizes. Needs to be optimized.
  *  
  *  Tony: 
  *  Incorporate mask tables similar to fbcon-cfb*.c in 2.4 API.  This speeds 
  *  up the code significantly.
  *  
- *  Code for depths not multiples of BITS_PER_LONG is still kludgy, which is
+ *  Code for depths not multiples of BITS_PER_WORD is still kludgy, which is
  *  still processed a bit at a time.   
  *
  *  Also need to add code to deal with cards endians that are different than
@@ -48,7 +48,11 @@
 #define DPRINTK(fmt, args...)
 #endif
 
-static u32 cfb_tab8[] = {
+/* The following code can *not* handle a 64-bit long.  */
+#define WORD u32
+#define BITS_PER_WORD 32
+
+static WORD const cfb_tab8[] = {
 #if defined(__BIG_ENDIAN)
     0x00000000,0x000000ff,0x0000ff00,0x0000ffff,
     0x00ff0000,0x00ff00ff,0x00ffff00,0x00ffffff,
@@ -64,7 +68,7 @@
 #endif
 };
 
-static u32 cfb_tab16[] = {
+static WORD const cfb_tab16[] = {
 #if defined(__BIG_ENDIAN)
     0x00000000, 0x0000ffff, 0xffff0000, 0xffffffff
 #elif defined(__LITTLE_ENDIAN)
@@ -74,11 +78,11 @@
 #endif
 };
 
-static u32 cfb_tab32[] = {
+static WORD const cfb_tab32[] = {
 	0x00000000, 0xffffffff
 };
 
-#if BITS_PER_LONG == 32
+#if BITS_PER_WORD == 32
 #define FB_WRITEL fb_writel
 #define FB_READL  fb_readl
 #else
@@ -87,7 +91,7 @@
 #endif 
 
 #if defined (__BIG_ENDIAN)
-#define LEFT_POS(bpp)          (BITS_PER_LONG - bpp)
+#define LEFT_POS(bpp)          (BITS_PER_WORD - bpp)
 #define NEXT_POS(pos, bpp)     ((pos) -= (bpp))
 #define SHIFT_HIGH(val, bits)  ((val) >> (bits))
 #define SHIFT_LOW(val, bits)   ((val) << (bits))
@@ -99,25 +103,25 @@
 #endif
 
 static inline void color_imageblit(struct fb_image *image, struct fb_info *p, u8 *dst1, 
-				   unsigned long start_index, unsigned long pitch_index)
+				   WORD start_index, WORD pitch_index)
 {
 	/* Draw the penguin */
 	int i, n;
-	unsigned long bitmask = SHIFT_LOW(~0UL, BITS_PER_LONG - p->var.bits_per_pixel);
-	unsigned long *palette = (unsigned long *) p->pseudo_palette;
-	unsigned long *dst, *dst2, color = 0, val, shift;
-	unsigned long null_bits = BITS_PER_LONG - p->var.bits_per_pixel; 
+	WORD bitmask = SHIFT_LOW(~0UL, BITS_PER_WORD - p->var.bits_per_pixel);
+	u32 *palette = (u32 *) p->pseudo_palette;
+	WORD *dst, *dst2, color = 0, val, shift;
+	WORD null_bits = BITS_PER_WORD - p->var.bits_per_pixel; 
 	u8 *src = image->data;
 
-	dst2 = (unsigned long *) dst1;
+	dst2 = (WORD *) dst1;
 	for (i = image->height; i--; ) {
 		n = image->width;
-		dst = (unsigned long *) dst1;
+		dst = (WORD *) dst1;
 		shift = 0;
 		val = 0;
 		
 		if (start_index) {
-			unsigned long start_mask = ~(SHIFT_HIGH(~0UL, start_index));
+			WORD start_mask = ~(SHIFT_HIGH(~0UL, start_index));
 
 			val = FB_READL(dst) & start_mask;
 			shift = start_index;
@@ -134,14 +138,14 @@
 				if (shift == null_bits)
 					val = 0;
 				else
-					val = SHIFT_LOW(color, BITS_PER_LONG - shift);
+					val = SHIFT_LOW(color, BITS_PER_WORD - shift);
 			}
 			shift += p->var.bits_per_pixel;
-			shift &= (BITS_PER_LONG - 1);
+			shift &= (BITS_PER_WORD - 1);
 			src++;
 		}
 		if (shift) {
-			unsigned long  end_mask = SHIFT_HIGH(~0UL, shift);
+			WORD end_mask = SHIFT_HIGH(~0UL, shift);
 
 			FB_WRITEL((FB_READL(dst) & end_mask) | val, dst);
 		}
@@ -149,35 +153,35 @@
 		if (pitch_index) {
 			dst2 += p->fix.line_length;
 			dst1 = (char *) dst2;
-			(unsigned long) dst1 &= ~(sizeof(unsigned long) - 1);
+			(size_t) dst1 &= ~(sizeof(WORD) - 1);
 
 			start_index += pitch_index;
-			start_index &= BITS_PER_LONG - 1;
+			start_index &= BITS_PER_WORD - 1;
 		}
 	}
 }
 
 static inline void slow_imageblit(struct fb_image *image, struct fb_info *p, u8 *dst1,
-				  unsigned long fgcolor, unsigned long bgcolor, 
-				  unsigned long start_index, unsigned long pitch_index)
+				  WORD fgcolor, WORD bgcolor, 
+				  WORD start_index, WORD pitch_index)
 {
-	unsigned long i, j, l = 8;
-	unsigned long shift, color, bpp = p->var.bits_per_pixel;
-	unsigned long *dst, *dst2, val, pitch = p->fix.line_length;
-	unsigned long null_bits = BITS_PER_LONG - bpp;
+	WORD i, j, l = 8;
+	WORD shift, color, bpp = p->var.bits_per_pixel;
+	WORD *dst, *dst2, val, pitch = p->fix.line_length;
+	WORD null_bits = BITS_PER_WORD - bpp;
 	u8 *src = image->data;
 	
-	dst2 = (unsigned long *) dst1;
+	dst2 = (WORD *) dst1;
 
 	for (i = image->height; i--; ) {
 		shift = 0;
 		val = 0;
 		j = image->width;
-		dst = (unsigned long *) dst1;
+		dst = (WORD *) dst1;
 
 		/* write leading bits */
 		if (start_index) {
-			unsigned long start_mask = ~(SHIFT_HIGH(~0UL, start_index));
+			WORD start_mask = ~(SHIFT_HIGH(~0UL, start_index));
 
 			val = FB_READL(dst) & start_mask;
 			shift = start_index;
@@ -196,15 +200,15 @@
 				if (shift == null_bits)
 					val = 0;
 				else
-					val = SHIFT_LOW(color, BITS_PER_LONG - shift);
+					val = SHIFT_LOW(color, BITS_PER_WORD - shift);
 			}
 			shift += bpp;
-			shift &= (BITS_PER_LONG - 1);
+			shift &= (BITS_PER_WORD - 1);
 			if (!l) { l = 8; src++; };
 		}
 		/* write trailing bits */
  		if (shift) {
-			unsigned long end_mask = SHIFT_HIGH(~0UL, shift);
+			WORD end_mask = SHIFT_HIGH(~0UL, shift);
 
 			FB_WRITEL((FB_READL(dst) & end_mask) | val, dst);
 		}
@@ -213,24 +217,24 @@
 		if (pitch_index) {
 			dst2 += pitch;
 			dst1 = (char *) dst2;
-			(unsigned long) dst1 &= ~(sizeof(unsigned long) - 1);
+			(size_t) dst1 &= ~(sizeof(WORD) - 1);
 
 			start_index += pitch_index;
-			start_index &= BITS_PER_LONG - 1;
+			start_index &= BITS_PER_WORD - 1;
 		}
 		
 	}
 }
 
 static inline void fast_imageblit(struct fb_image *image, struct fb_info *p, u8 *dst1, 
-				  unsigned long fgcolor, unsigned long bgcolor) 
+				  WORD fgcolor, WORD bgcolor) 
 {
 	int i, j, k, l = 8, n;
-	unsigned long bit_mask, end_mask, eorx; 
-	unsigned long fgx = fgcolor, bgx = bgcolor, pad, bpp = p->var.bits_per_pixel;
-	unsigned long tmp = (1 << bpp) - 1;
-	unsigned long ppw = BITS_PER_LONG/bpp, ppos;
-	unsigned long *dst;
+	WORD bit_mask, end_mask, eorx; 
+	WORD fgx = fgcolor, bgx = bgcolor, pad, bpp = p->var.bits_per_pixel;
+	WORD tmp = (1 << bpp) - 1;
+	WORD ppw = BITS_PER_WORD/bpp, ppos;
+	WORD *dst;
 	u32 *tab = NULL;
 	char *src = image->data;
 		
@@ -263,7 +267,7 @@
 	k = image->width/ppw;
 
 	for (i = image->height; i--; ) {
-		dst = (unsigned long *) dst1;
+		dst = (WORD *) dst1;
 		
 		for (j = k; j--; ) {
 			l -= ppw;
@@ -291,8 +295,8 @@
 void cfb_imageblit(struct fb_info *p, struct fb_image *image)
 {
 	int x2, y2, vxres, vyres;
-	unsigned long fgcolor, bgcolor, start_index, bitstart, pitch_index = 0;
-	unsigned long bpl = sizeof(unsigned long), bpp = p->var.bits_per_pixel;
+	WORD fgcolor, bgcolor, start_index, bitstart, pitch_index = 0;
+	WORD bpl = sizeof(WORD), bpp = p->var.bits_per_pixel;
 	u8 *dst1;
 
 	vxres = p->var.xres_virtual;
@@ -315,7 +319,7 @@
 	image->height = y2 - image->dy;
 
 	bitstart = (image->dy * p->fix.line_length * 8) + (image->dx * bpp);
-	start_index = bitstart & (BITS_PER_LONG - 1);
+	start_index = bitstart & (BITS_PER_WORD - 1);
 	pitch_index = (p->fix.line_length & (bpl - 1)) * 8;
 
 	bitstart /= 8;
@@ -332,7 +336,7 @@
 			bgcolor = image->bg_color;
 		}	
 		
-		if (BITS_PER_LONG % bpp == 0 && !start_index && !pitch_index && 
+		if (BITS_PER_WORD % bpp == 0 && !start_index && !pitch_index && 
 		    bpp >= 8 && bpp <= 32 && (image->width & 7) == 0) 
 			fast_imageblit(image, p, dst1, fgcolor, bgcolor);
 		else 

===================================================================


This BitKeeper patch contains the following changesets:
+
## Wrapped with gzip_uu ##


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`
end


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Re: [Linux-fbdev-devel] [FB PATCH] cfbimgblt isn't 64-bit clean

[James Simmons]

> The text is written as if it's thinking about handling 64-bit
> unsigned long, but it doesn't.  The tables that map bits to
> pixels are completely unprepared for this.
> 
> I thought about widening the tables, but I thought they'd get
> unreasonably large.  There's no reason not to go ahead and 
> handle this 32-bits at a time.

I thought the tables would come back to haunt us. The only reason the 
tables where introduced was for speed enhancements. I reason the code is 
extra complex was so you could pass 64 bits of data across the bus. I 
still like to see that happen still. What do you think?

Re: [FB PATCH] cfbimgblt isn't 64-bit clean

[Antonino Daplas]

On Sun, 2002-12-29 at 09:16, James Simmons wrote:
> 
> > The text is written as if it's thinking about handling 64-bit
> > unsigned long, but it doesn't.  The tables that map bits to
> > pixels are completely unprepared for this.
> > 
> > I thought about widening the tables, but I thought they'd get
> > unreasonably large.  There's no reason not to go ahead and 
> > handle this 32-bits at a time.
> 
> I thought the tables would come back to haunt us. The only reason the 
> tables where introduced was for speed enhancements. I reason the code is 
> extra complex was so you could pass 64 bits of data across the bus. I 
> still like to see that happen still. What do you think?
> 

Only fast_imageblit() should be affected.  color_imageblit() and
slow_imageblit() will not be affected.  

fast_imageblit() is used only for 8, 16 and 32 bpp.  We can remove
fast_imageblit() and just use slow_imageblit() for all color depths, but
it will suffer a significant slowdown. 

Or we can change fast_imageblit() to always access the framebuffer
memory 32-bits at a time. The attached patch should fix this.

Tony

diff -Naur linux-2.5.42/drivers/video/cfbimgblt.c linux/drivers/video/cfbimgblt.c
--- linux-2.5.42/drivers/video/cfbimgblt.c	2002-12-29 14:44:04.000000000 +0000
+++ linux/drivers/video/cfbimgblt.c	2002-12-29 14:44:23.000000000 +0000
@@ -88,11 +88,13 @@
 
 #if defined (__BIG_ENDIAN)
 #define LEFT_POS(bpp)          (BITS_PER_LONG - bpp)
+#define LEFT_POS32(bpp)        (32 - bpp)
 #define NEXT_POS(pos, bpp)     ((pos) -= (bpp))
 #define SHIFT_HIGH(val, bits)  ((val) >> (bits))
 #define SHIFT_LOW(val, bits)   ((val) << (bits))
 #else
 #define LEFT_POS(bpp)          (0)
+#define LEFT_POS32(bpp)        (0)
 #define NEXT_POS(pos, bpp)     ((pos) += (bpp))
 #define SHIFT_HIGH(val, bits)  ((val) << (bits))
 #define SHIFT_LOW(val, bits)   ((val) >> (bits))
@@ -223,25 +225,25 @@
 }
 
 static inline void fast_imageblit(struct fb_image *image, struct fb_info *p, u8 *dst1, 
-				  unsigned long fgcolor, unsigned long bgcolor) 
+				  u32 fgcolor, u32 bgcolor) 
 {
 	int i, j, k, l = 8, n;
-	unsigned long bit_mask, end_mask, eorx; 
-	unsigned long fgx = fgcolor, bgx = bgcolor, pad, bpp = p->var.bits_per_pixel;
-	unsigned long tmp = (1 << bpp) - 1;
-	unsigned long ppw = BITS_PER_LONG/bpp, ppos;
-	unsigned long *dst;
+	u32 bit_mask, end_mask, eorx; 
+	u32 fgx = fgcolor, bgx = bgcolor, pad, bpp = p->var.bits_per_pixel;
+	u32 tmp = (1 << bpp) - 1;
+	u32 ppw = 32/bpp, ppos;
+	u32 *dst;
 	u32 *tab = NULL;
 	char *src = image->data;
 		
-	switch (ppw) {
-	case 4:
+	switch (bpp) {
+	case 8:
 		tab = cfb_tab8;
 		break;
-	case 2:
+	case 16:
 		tab = cfb_tab16;
 		break;
-	case 1:
+	case 32:
 		tab = cfb_tab32;
 		break;
 	}
@@ -263,17 +265,17 @@
 	k = image->width/ppw;
 
 	for (i = image->height; i--; ) {
-		dst = (unsigned long *) dst1;
+		dst = (u32 *) dst1;
 		
 		for (j = k; j--; ) {
 			l -= ppw;
 			end_mask = tab[(*src >> l) & bit_mask]; 
-			FB_WRITEL((end_mask & eorx)^bgx, dst++);
+			fb_writel((end_mask & eorx)^bgx, dst++);
 			if (!l) { l = 8; src++; }
 		}
 		if (n) {
 			end_mask = 0;	
-			ppos = LEFT_POS(bpp);
+			ppos = LEFT_POS32(bpp);
 			for (j = n; j > 0; j--) {
 				l--;
 				if (*src & (1 << l))
@@ -281,7 +283,7 @@
 				NEXT_POS(ppos, bpp);
 				if (!l) { l = 8; src++; }
 			}
-			FB_WRITEL((end_mask & eorx)^bgx, dst++);
+			fb_writel((end_mask & eorx)^bgx, dst++);
 		}
 		l -= pad;		
 		dst1 += p->fix.line_length;	
@@ -337,7 +339,7 @@
 		
 		if (BITS_PER_LONG % bpp == 0 && !start_index && !pitch_index && 
 		    bpp >= 8 && bpp <= 32 && (image->width & 7) == 0) 
-			fast_imageblit(image, p, dst1, fgcolor, bgcolor);
+			fast_imageblit(image, p, dst1, (u32) fgcolor, (u32) bgcolor);
 		else 
 			slow_imageblit(image, p, dst1, fgcolor, bgcolor, start_index, pitch_index);
 	}



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Re: [Linux-fbdev-devel] [FB PATCH] cfbimgblt isn't 64-bit clean

[Richard Henderson]

On Sun, Dec 29, 2002 at 10:58:43PM +0800, Antonino Daplas wrote:
> Only fast_imageblit() should be affected.  color_imageblit() and
> slow_imageblit() will not be affected.  

Indeed.

> Or we can change fast_imageblit() to always access the framebuffer
> memory 32-bits at a time. The attached patch should fix this.

This is probably better than the wholesale conversion to
32-bits that I did.

For the most part I don't care anymore; I've implemented a
hardware accelerated version for depth==1 in tgafb.c now.  ;-)


r~