avr/qmk/lufa - [no description]

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author	Dean Camera <dean@fourwalledcubicle.com>	2014-09-14 16:52:36 +1000
committer	Dean Camera <dean@fourwalledcubicle.com>	2014-09-14 16:52:36 +1000
commit	5df2027e7950a569ac3e928d4c6fb9f06e265707 (patch)
tree	343957d74bc0dd85dda84e91413e8f2d8eb76955 /Demos/Device/LowLevel/KeyboardMouse/KeyboardMouse.c
parent	41634c45303643e3756b3af9d0123095942481bb (diff)
download	lufa-5df2027e7950a569ac3e928d4c6fb9f06e265707.tar.gz lufa-5df2027e7950a569ac3e928d4c6fb9f06e265707.tar.bz2 lufa-5df2027e7950a569ac3e928d4c6fb9f06e265707.zip

Minor documentation improvements.

Diffstat (limited to 'Demos/Device/LowLevel/KeyboardMouse/KeyboardMouse.c')

0 files changed, 0 insertions, 0 deletions

From 36be92675cdb5eb76ec03997b6ee0b8a1863b08a Mon Sep 17 00:00:00 2001 From: Harm Hanemaaijer <fgenfb@yahoo.com> Date: Thu, 20 Jun 2013 20:21:39 +0200 Subject: [PATCH] Speed up console framebuffer imageblit function Especially on platforms with a slower CPU but a relatively high framebuffer fill bandwidth, like current ARM devices, the existing console monochrome imageblit function used to draw console text is suboptimal for common pixel depths such as 16bpp and 32bpp. The existing code is quite general and can deal with several pixel depths. By creating special case functions for 16bpp and 32bpp, by far the most common pixel formats used on modern systems, a significant speed-up is attained which can be readily felt on ARM-based devices like the Raspberry Pi and the Allwinner platform, but should help any platform using the fb layer. The special case functions allow constant folding, eliminating a number of instructions including divide operations, and allow the use of an unrolled loop, eliminating instructions with a variable shift size, reducing source memory access instructions, and eliminating excessive branching. These unrolled loops also allow much better code optimization by the C compiler. The code that selects which optimized variant is used is also simplified, eliminating integer divide instructions. The speed-up, measured by timing 'cat file.txt' in the console, varies between 40% and 70%, when testing on the Raspberry Pi and Allwinner ARM-based platforms, depending on font size and the pixel depth, with the greater benefit for 32bpp. Signed-off-by: Harm Hanemaaijer <fgenfb@yahoo.com> --- drivers/video/fbdev/core/cfbimgblt.c | 152 ++++++++++++++++++++++++++- 1 file changed, 147 insertions(+), 5 deletions(-) --- a/drivers/video/fbdev/core/cfbimgblt.c +++ b/drivers/video/fbdev/core/cfbimgblt.c @@ -28,6 +28,11 @@ * * Also need to add code to deal with cards endians that are different than * the native cpu endians. I also need to deal with MSB position in the word. + * Modified by Harm Hanemaaijer (fgenfb@yahoo.com) 2013: + * - Provide optimized versions of fast_imageblit for 16 and 32bpp that are + * significantly faster than the previous implementation. + * - Simplify the fast/slow_imageblit selection code, avoiding integer + * divides. */ #include <linux/module.h> #include <linux/string.h> @@ -262,6 +267,133 @@ static inline void fast_imageblit(const } } +/* + * Optimized fast_imageblit for bpp == 16. ppw = 2, bit_mask = 3 folded + * into the code, main loop unrolled. + */ + +static inline void fast_imageblit16(const struct fb_image *image, + struct fb_info *p, u8 __iomem * dst1, + u32 fgcolor, u32 bgcolor) +{ + u32 fgx = fgcolor, bgx = bgcolor; + u32 spitch = (image->width + 7) / 8; + u32 end_mask, eorx; + const char *s = image->data, *src; + u32 __iomem *dst; + const u32 *tab = NULL; + int i, j, k; + + tab = fb_be_math(p) ? cfb_tab16_be : cfb_tab16_le; + + fgx <<= 16; + bgx <<= 16; + fgx |= fgcolor; + bgx |= bgcolor; + + eorx = fgx ^ bgx; + k = image->width / 2; + + for (i = image->height; i--;) { + dst = (u32 __iomem *) dst1; + src = s; + + j = k; + while (j >= 4) { + u8 bits = *src; + end_mask = tab[(bits >> 6) & 3]; + FB_WRITEL((end_mask & eorx) ^ bgx, dst++); + end_mask = tab[(bits >> 4) & 3]; + FB_WRITEL((end_mask & eorx) ^ bgx, dst++); + end_mask = tab[(bits >> 2) & 3]; + FB_WRITEL((end_mask & eorx) ^ bgx, dst++); + end_mask = tab[bits & 3]; + FB_WRITEL((end_mask & eorx) ^ bgx, dst++); + src++; + j -= 4; + } + if (j != 0) { + u8 bits = *src; + end_mask = tab[(bits >> 6) & 3]; + FB_WRITEL((end_mask & eorx) ^ bgx, dst++); + if (j >= 2) { + end_mask = tab[(bits >> 4) & 3]; + FB_WRITEL((end_mask & eorx) ^ bgx, dst++); + if (j == 3) { + end_mask = tab[(bits >> 2) & 3]; + FB_WRITEL((end_mask & eorx) ^ bgx, dst); + } + } + } + dst1 += p->fix.line_length; + s += spitch; + } +} + +/* + * Optimized fast_imageblit for bpp == 32. ppw = 1, bit_mask = 1 folded + * into the code, main loop unrolled. + */ + +static inline void fast_imageblit32(const struct fb_image *image, + struct fb_info *p, u8 __iomem * dst1, + u32 fgcolor, u32 bgcolor) +{ + u32 fgx = fgcolor, bgx = bgcolor; + u32 spitch = (image->width + 7) / 8; + u32 end_mask, eorx; + const char *s = image->data, *src; + u32 __iomem *dst; + const u32 *tab = NULL; + int i, j, k; + + tab = cfb_tab32; + + eorx = fgx ^ bgx; + k = image->width; + + for (i = image->height; i--;) { + dst = (u32 __iomem *) dst1; + src = s; + + j = k; + while (j >= 8) { + u8 bits = *src; + end_mask = tab[(bits >> 7) & 1]; + FB_WRITEL((end_mask & eorx) ^ bgx, dst++); + end_mask = tab[(bits >> 6) & 1]; + FB_WRITEL((end_mask & eorx) ^ bgx, dst++); + end_mask = tab[(bits >> 5) & 1]; + FB_WRITEL((end_mask & eorx) ^ bgx, dst++); + end_mask = tab[(bits >> 4) & 1]; + FB_WRITEL((end_mask & eorx) ^ bgx, dst++); + end_mask = tab[(bits >> 3) & 1]; + FB_WRITEL((end_mask & eorx) ^ bgx, dst++); + end_mask = tab[(bits >> 2) & 1]; + FB_WRITEL((end_mask & eorx) ^ bgx, dst++); + end_mask = tab[(bits >> 1) & 1]; + FB_WRITEL((end_mask & eorx) ^ bgx, dst++); + end_mask = tab[bits & 1]; + FB_WRITEL((end_mask & eorx) ^ bgx, dst++); + src++; + j -= 8; + } + if (j != 0) { + u32 bits = (u32) * src; + while (j > 1) { + end_mask = tab[(bits >> 7) & 1]; + FB_WRITEL((end_mask & eorx) ^ bgx, dst++); + bits <<= 1; + j--; + } + end_mask = tab[(bits >> 7) & 1]; + FB_WRITEL((end_mask & eorx) ^ bgx, dst); + } + dst1 += p->fix.line_length; + s += spitch; + } +} + void cfb_imageblit(struct fb_info *p, const struct fb_image *image) { u32 fgcolor, bgcolor, start_index, bitstart, pitch_index = 0; @@ -294,11 +426,21 @@ void cfb_imageblit(struct fb_info *p, co bgcolor = image->bg_color; } - if (32 % bpp == 0 && !start_index && !pitch_index && - ((width & (32/bpp-1)) == 0) && - bpp >= 8 && bpp <= 32) - fast_imageblit(image, p, dst1, fgcolor, bgcolor); - else + if (!start_index && !pitch_index) { + if (bpp == 32) + fast_imageblit32(image, p, dst1, fgcolor, + bgcolor); + else if (bpp == 16 && (width & 1) == 0) + fast_imageblit16(image, p, dst1, fgcolor, + bgcolor); + else if (bpp == 8 && (width & 3) == 0) + fast_imageblit(image, p, dst1, fgcolor, + bgcolor); + else + slow_imageblit(image, p, dst1, fgcolor, + bgcolor, + start_index, pitch_index); + } else slow_imageblit(image, p, dst1, fgcolor, bgcolor, start_index, pitch_index); } else


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