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210 lines
6.5 KiB
Diff
210 lines
6.5 KiB
Diff
From f4489532d7a73ded68e1b8a815a71b0fe25e9e21 Mon Sep 17 00:00:00 2001
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From: Harm Hanemaaijer <fgenfb@yahoo.com>
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Date: Thu, 20 Jun 2013 20:21:39 +0200
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Subject: [PATCH] Speed up console framebuffer imageblit function
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Especially on platforms with a slower CPU but a relatively high
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framebuffer fill bandwidth, like current ARM devices, the existing
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console monochrome imageblit function used to draw console text is
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suboptimal for common pixel depths such as 16bpp and 32bpp. The existing
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code is quite general and can deal with several pixel depths. By creating
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special case functions for 16bpp and 32bpp, by far the most common pixel
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formats used on modern systems, a significant speed-up is attained
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which can be readily felt on ARM-based devices like the Raspberry Pi
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and the Allwinner platform, but should help any platform using the
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fb layer.
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The special case functions allow constant folding, eliminating a number
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of instructions including divide operations, and allow the use of an
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unrolled loop, eliminating instructions with a variable shift size,
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reducing source memory access instructions, and eliminating excessive
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branching. These unrolled loops also allow much better code optimization
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by the C compiler. The code that selects which optimized variant is used
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is also simplified, eliminating integer divide instructions.
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The speed-up, measured by timing 'cat file.txt' in the console, varies
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between 40% and 70%, when testing on the Raspberry Pi and Allwinner
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ARM-based platforms, depending on font size and the pixel depth, with
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the greater benefit for 32bpp.
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Signed-off-by: Harm Hanemaaijer <fgenfb@yahoo.com>
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---
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drivers/video/fbdev/core/cfbimgblt.c | 152 ++++++++++++++++++++++++++-
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1 file changed, 147 insertions(+), 5 deletions(-)
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--- a/drivers/video/fbdev/core/cfbimgblt.c
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+++ b/drivers/video/fbdev/core/cfbimgblt.c
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@@ -28,6 +28,11 @@
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*
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* Also need to add code to deal with cards endians that are different than
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* the native cpu endians. I also need to deal with MSB position in the word.
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+ * Modified by Harm Hanemaaijer (fgenfb@yahoo.com) 2013:
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+ * - Provide optimized versions of fast_imageblit for 16 and 32bpp that are
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+ * significantly faster than the previous implementation.
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+ * - Simplify the fast/slow_imageblit selection code, avoiding integer
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+ * divides.
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*/
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#include <linux/module.h>
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#include <linux/string.h>
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@@ -262,6 +267,133 @@ static inline void fast_imageblit(const
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}
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}
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+/*
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+ * Optimized fast_imageblit for bpp == 16. ppw = 2, bit_mask = 3 folded
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+ * into the code, main loop unrolled.
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+ */
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+
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+static inline void fast_imageblit16(const struct fb_image *image,
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+ struct fb_info *p, u8 __iomem * dst1,
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+ u32 fgcolor, u32 bgcolor)
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+{
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+ u32 fgx = fgcolor, bgx = bgcolor;
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+ u32 spitch = (image->width + 7) / 8;
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+ u32 end_mask, eorx;
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+ const char *s = image->data, *src;
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+ u32 __iomem *dst;
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+ const u32 *tab = NULL;
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+ int i, j, k;
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+
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+ tab = fb_be_math(p) ? cfb_tab16_be : cfb_tab16_le;
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+
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+ fgx <<= 16;
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+ bgx <<= 16;
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+ fgx |= fgcolor;
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+ bgx |= bgcolor;
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+
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+ eorx = fgx ^ bgx;
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+ k = image->width / 2;
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+
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+ for (i = image->height; i--;) {
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+ dst = (u32 __iomem *) dst1;
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+ src = s;
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+
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+ j = k;
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+ while (j >= 4) {
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+ u8 bits = *src;
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+ end_mask = tab[(bits >> 6) & 3];
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+ FB_WRITEL((end_mask & eorx) ^ bgx, dst++);
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+ end_mask = tab[(bits >> 4) & 3];
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+ FB_WRITEL((end_mask & eorx) ^ bgx, dst++);
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+ end_mask = tab[(bits >> 2) & 3];
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+ FB_WRITEL((end_mask & eorx) ^ bgx, dst++);
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+ end_mask = tab[bits & 3];
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+ FB_WRITEL((end_mask & eorx) ^ bgx, dst++);
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+ src++;
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+ j -= 4;
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+ }
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+ if (j != 0) {
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+ u8 bits = *src;
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+ end_mask = tab[(bits >> 6) & 3];
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+ FB_WRITEL((end_mask & eorx) ^ bgx, dst++);
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+ if (j >= 2) {
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+ end_mask = tab[(bits >> 4) & 3];
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+ FB_WRITEL((end_mask & eorx) ^ bgx, dst++);
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+ if (j == 3) {
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+ end_mask = tab[(bits >> 2) & 3];
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+ FB_WRITEL((end_mask & eorx) ^ bgx, dst);
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+ }
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+ }
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+ }
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+ dst1 += p->fix.line_length;
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+ s += spitch;
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+ }
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+}
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+
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+/*
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+ * Optimized fast_imageblit for bpp == 32. ppw = 1, bit_mask = 1 folded
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+ * into the code, main loop unrolled.
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+ */
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+
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+static inline void fast_imageblit32(const struct fb_image *image,
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+ struct fb_info *p, u8 __iomem * dst1,
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+ u32 fgcolor, u32 bgcolor)
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+{
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+ u32 fgx = fgcolor, bgx = bgcolor;
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+ u32 spitch = (image->width + 7) / 8;
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+ u32 end_mask, eorx;
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+ const char *s = image->data, *src;
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+ u32 __iomem *dst;
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+ const u32 *tab = NULL;
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+ int i, j, k;
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+
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+ tab = cfb_tab32;
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+
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+ eorx = fgx ^ bgx;
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+ k = image->width;
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+
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+ for (i = image->height; i--;) {
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+ dst = (u32 __iomem *) dst1;
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+ src = s;
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+
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+ j = k;
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+ while (j >= 8) {
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+ u8 bits = *src;
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+ end_mask = tab[(bits >> 7) & 1];
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+ FB_WRITEL((end_mask & eorx) ^ bgx, dst++);
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+ end_mask = tab[(bits >> 6) & 1];
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+ FB_WRITEL((end_mask & eorx) ^ bgx, dst++);
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+ end_mask = tab[(bits >> 5) & 1];
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+ FB_WRITEL((end_mask & eorx) ^ bgx, dst++);
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+ end_mask = tab[(bits >> 4) & 1];
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+ FB_WRITEL((end_mask & eorx) ^ bgx, dst++);
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+ end_mask = tab[(bits >> 3) & 1];
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+ FB_WRITEL((end_mask & eorx) ^ bgx, dst++);
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+ end_mask = tab[(bits >> 2) & 1];
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+ FB_WRITEL((end_mask & eorx) ^ bgx, dst++);
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+ end_mask = tab[(bits >> 1) & 1];
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+ FB_WRITEL((end_mask & eorx) ^ bgx, dst++);
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+ end_mask = tab[bits & 1];
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+ FB_WRITEL((end_mask & eorx) ^ bgx, dst++);
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+ src++;
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+ j -= 8;
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+ }
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+ if (j != 0) {
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+ u32 bits = (u32) * src;
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+ while (j > 1) {
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+ end_mask = tab[(bits >> 7) & 1];
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+ FB_WRITEL((end_mask & eorx) ^ bgx, dst++);
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+ bits <<= 1;
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+ j--;
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+ }
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+ end_mask = tab[(bits >> 7) & 1];
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+ FB_WRITEL((end_mask & eorx) ^ bgx, dst);
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+ }
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+ dst1 += p->fix.line_length;
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+ s += spitch;
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+ }
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+}
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+
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void cfb_imageblit(struct fb_info *p, const struct fb_image *image)
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{
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u32 fgcolor, bgcolor, start_index, bitstart, pitch_index = 0;
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@@ -294,11 +426,21 @@ void cfb_imageblit(struct fb_info *p, co
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bgcolor = image->bg_color;
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}
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- if (32 % bpp == 0 && !start_index && !pitch_index &&
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- ((width & (32/bpp-1)) == 0) &&
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- bpp >= 8 && bpp <= 32)
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- fast_imageblit(image, p, dst1, fgcolor, bgcolor);
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- else
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+ if (!start_index && !pitch_index) {
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+ if (bpp == 32)
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+ fast_imageblit32(image, p, dst1, fgcolor,
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+ bgcolor);
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+ else if (bpp == 16 && (width & 1) == 0)
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+ fast_imageblit16(image, p, dst1, fgcolor,
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+ bgcolor);
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+ else if (bpp == 8 && (width & 3) == 0)
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+ fast_imageblit(image, p, dst1, fgcolor,
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+ bgcolor);
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+ else
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+ slow_imageblit(image, p, dst1, fgcolor,
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+ bgcolor,
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+ start_index, pitch_index);
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+ } else
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slow_imageblit(image, p, dst1, fgcolor, bgcolor,
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start_index, pitch_index);
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} else
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