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SubjectRe: [Linux-fbdev-devel] [PATCH 1/1 2.6.13] framebuffer: bit_putcs() optimization for 8x* fonts

>Something like below, which has the advantange that there is still only
>one implementation of the function
>
True, that´s a great advantage.

> and if it's still slower, we really need to check the compiler
>
>
Please have a look at the following patch. It takes your idea of
inlining but moves
the special cases into the macro, speeding things up for the very likely
case of
s_pitch == 1 and the less likely case of s_pitch of 2. Treating s_pitch
== 2 special
gives a still significant performance improvement of more than 10 % for
16x30
fonts.

This way also bit_putcs looks better again ...

Andrew, as this way is better than and still as fast as my first
approach I think
framebuffer-bit_putcs-optimization-for-8x.patch should be reverted and the
following patch should be applied instead.

Antonino, Roman, Geert, do you agree?


cu,
knut

diff -uprN -X linux/Documentation/dontdiff -x '*.bak' -x '*.ctx' linuxorig/drivers/video/console/bitblit.c linux/drivers/video/console/bitblit.c
--- linuxorig/drivers/video/console/bitblit.c 2005-08-29 01:41:01.000000000 +0200
+++ linux/drivers/video/console/bitblit.c 2005-08-31 10:06:22.000000000 +0200
@@ -175,7 +175,7 @@ static void bit_putcs(struct vc_data *vc
src = buf;
}

- fb_pad_aligned_buffer(dst, pitch, src, idx, image.height);
+ __fb_pad_aligned_buffer(dst, pitch, src, idx, image.height);
dst += width;
}
}
diff -uprN -X linux/Documentation/dontdiff -x '*.bak' -x '*.ctx' linuxorig/drivers/video/fbmem.c linux/drivers/video/fbmem.c
--- linuxorig/drivers/video/fbmem.c 2005-08-29 01:41:01.000000000 +0200
+++ linux/drivers/video/fbmem.c 2005-08-31 13:36:16.000000000 +0200
@@ -80,15 +80,7 @@ EXPORT_SYMBOL(fb_get_color_depth);
*/
void fb_pad_aligned_buffer(u8 *dst, u32 d_pitch, u8 *src, u32 s_pitch, u32 height)
{
- int i, j;
-
- for (i = height; i--; ) {
- /* s_pitch is a few bytes at the most, memcpy is suboptimal */
- for (j = 0; j < s_pitch; j++)
- dst[j] = src[j];
- src += s_pitch;
- dst += d_pitch;
- }
+ __fb_pad_aligned_buffer(dst, d_pitch, src, s_pitch, height);
}
EXPORT_SYMBOL(fb_pad_aligned_buffer);

diff -uprN -X linux/Documentation/dontdiff -x '*.bak' -x '*.ctx' linuxorig/include/linux/fb.h linux/include/linux/fb.h
--- linuxorig/include/linux/fb.h 2005-08-29 01:41:01.000000000 +0200
+++ linux/include/linux/fb.h 2005-08-31 12:45:08.000000000 +0200
@@ -824,6 +824,38 @@ extern int fb_get_color_depth(struct fb_
extern int fb_get_options(char *name, char **option);
extern int fb_new_modelist(struct fb_info *info);

+
+/*
+ * Don't change without testing performance of framebuffer
+ * bitblitting. Inlining is necessary for performance reasons.
+ * Although the code might not _look_ fast because of some
+ * multiplications, it really _is_ fast as it is easier for gcc
+ * to optimize well.
+ */
+
+static inline void __fb_pad_aligned_buffer(u8 *dst, u32 d_pitch, u8 *src,
+ u32 s_pitch, u32 height)
+{
+ int i, j;
+
+ if (likely(s_pitch==1))
+ for(i=0; i < height; i++)
+ dst[d_pitch*i] = src[i];
+ else if (s_pitch==2)
+ for(i=0; i < height; i++) {
+ *(u16 *)dst = ((u16 *)src)[i];
+ dst += d_pitch;
+ }
+ else {
+ d_pitch -= s_pitch;
+ for (i = height; i--; ) {
+ for (j = 0; j < s_pitch; j++)
+ *dst++ = *src++;
+ dst += d_pitch;
+ }
+ }
+}
+
extern struct fb_info *registered_fb[FB_MAX];
extern int num_registered_fb;




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