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/* Libart_LGPL - library of basic graphic primitives
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* Copyright (C) 1998 Raph Levien
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 02111-1307, USA.
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#include <string.h> /* for memset */
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/* Basic operators for manipulating 24-bit packed RGB buffers. */
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#define COLOR_RUN_SIMPLE
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#ifdef COLOR_RUN_SIMPLE
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/* This is really slow. Is there any way we might speed it up?
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First, maybe we should be working at 32-bit alignment. Then,
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this can be a simple loop over word stores.
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Second, we can keep working at 24-bit alignment, but have some
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intelligence about storing. For example, we can iterate over
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4-pixel chunks (aligned at 4 pixels), with an inner loop
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One source of extra complexity is the need to make sure linebuf is
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aligned to a 32-bit boundary.
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This second alternative has some complexity to it, but is
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appealing because it really minimizes the memory bandwidth. */
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art_rgb_fill_run_ (art_u8 *buf, art_u32 rgb, int n)
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art_u32 *b = (art_u32 *)buf;
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for (i = 0; i < n; i++)
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#ifdef COLOR_RUN_COMPLEX
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/* This implements the second of the two ideas above. The test results
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are _very_ encouraging - it seems the speed is within 10% of
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memset, which is quite good! */
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* art_rgb_fill_run: fill a buffer a solid RGB color.
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* @buf: Buffer to fill.
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* @r: Red, range 0..255.
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* @g: Green, range 0..255.
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* @b: Blue, range 0..255.
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* @n: Number of RGB triples to fill.
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* Fills a buffer with @n copies of the (@r, @g, @b) triple. Thus,
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* locations @buf (inclusive) through @buf + 3 * @n (exclusive) are
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* The implementation of this routine is very highly optimized.
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art_rgb_fill_run_ (art_u8 *buf, art_u32 rgb, int n)
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unsigned int v1, v2, v3;
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for (i = 0; i < n; i++)
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/* handle prefix up to byte alignment */
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/* I'm worried about this cast on sizeof(long) != sizeof(uchar *)
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architectures, but it _should_ work. */
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for (i = 0; ((unsigned long)buf) & 3; i++)
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#ifndef WORDS_BIGENDIAN
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v1 = r | (g << 8) | (b << 16) | (r << 24);
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v1 = (r << 24) | (g << 16) | (b << 8) | r;
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for (; i < n - 3; i += 4)
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((art_u32 *)buf)[0] = v1;
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((art_u32 *)buf)[1] = v2;
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((art_u32 *)buf)[2] = v3;
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((art_u32 *)buf)[1] = v1;
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((art_u32 *)buf)[2] = v2;
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((art_u32 *)buf)[3] = v3;
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* art_rgb_run_alpha: Render semitransparent color over RGB buffer.
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* @buf: Buffer for rendering.
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* @r: Red, range 0..255.
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* @g: Green, range 0..255.
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* @b: Blue, range 0..255.
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* @alpha: Alpha, range 0..256.
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* @n: Number of RGB triples to render.
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* Renders a sequential run of solid (@r, @g, @b) color over @buf with
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art_rgb_run_alpha_ (art_u8 *buf, art_u8 r, art_u8 g, art_u8 b, int alpha, int n)
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for (i = 0; i < n; i++)
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*buf++ = v + (((b - v) * alpha + 0x80) >> 8);
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*buf++ = v + (((g - v) * alpha + 0x80) >> 8);
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*buf++ = v + (((r - v) * alpha + 0x80) >> 8);