1 /* Libart_LGPL - library of basic graphic primitives
2 * Copyright (C) 1998 Raph Levien
3 *
4 * This library is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Library General Public
6 * License as published by the Free Software Foundation; either
7 * version 2 of the License, or (at your option) any later version.
8 *
9 * This library is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * Library General Public License for more details.
13 *
14 * You should have received a copy of the GNU Library General Public
15 * License along with this library; if not, write to the
16 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
17 * Boston, MA 02111-1307, USA.
18 */
19
20 #include "config.h"
21 #include "art_rgb.h"
22
23 #include <string.h> /* for memset */
24
25 /* Basic operators for manipulating 24-bit packed RGB buffers. */
26
27 #define COLOR_RUN_COMPLEX
28
29 #ifdef COLOR_RUN_SIMPLE
30 /* This is really slow. Is there any way we might speed it up?
31 Two ideas:
32
33 First, maybe we should be working at 32-bit alignment. Then,
34 this can be a simple loop over word stores.
35
36 Second, we can keep working at 24-bit alignment, but have some
37 intelligence about storing. For example, we can iterate over
38 4-pixel chunks (aligned at 4 pixels), with an inner loop
39 something like:
40
41 *buf++ = v1;
42 *buf++ = v2;
43 *buf++ = v3;
44
45 One source of extra complexity is the need to make sure linebuf is
46 aligned to a 32-bit boundary.
47
48 This second alternative has some complexity to it, but is
49 appealing because it really minimizes the memory bandwidth. */
50 void
art_rgb_fill_run(art_u8 * buf,art_u8 r,art_u8 g,art_u8 b,gint n)51 art_rgb_fill_run (art_u8 *buf, art_u8 r, art_u8 g, art_u8 b, gint n)
52 {
53 int i;
54
55 if (r == g && g == b)
56 {
57 memset (buf, g, n + n + n);
58 }
59 else
60 {
61 for (i = 0; i < n; i++)
62 {
63 *buf++ = r;
64 *buf++ = g;
65 *buf++ = b;
66 }
67 }
68 }
69 #endif
70
71 #ifdef COLOR_RUN_COMPLEX
72 /* This implements the second of the two ideas above. The test results
73 are _very_ encouraging - it seems the speed is within 10% of
74 memset, which is quite good! */
75 /**
76 * art_rgb_fill_run: fill a buffer a solid RGB color.
77 * @buf: Buffer to fill.
78 * @r: Red, range 0..255.
79 * @g: Green, range 0..255.
80 * @b: Blue, range 0..255.
81 * @n: Number of RGB triples to fill.
82 *
83 * Fills a buffer with @n copies of the (@r, @g, @b) triple. Thus,
84 * locations @buf (inclusive) through @buf + 3 * @n (exclusive) are
85 * written.
86 *
87 * The implementation of this routine is very highly optimized.
88 **/
89 void
art_rgb_fill_run(art_u8 * buf,art_u8 r,art_u8 g,art_u8 b,int n)90 art_rgb_fill_run (art_u8 *buf, art_u8 r, art_u8 g, art_u8 b, int n)
91 {
92 int i;
93 unsigned int v1, v2, v3;
94
95 if (r == g && g == b)
96 {
97 memset (buf, g, n + n + n);
98 }
99 else
100 {
101 if (n < 8)
102 {
103 for (i = 0; i < n; i++)
104 {
105 *buf++ = r;
106 *buf++ = g;
107 *buf++ = b;
108 }
109 } else {
110 /* handle prefix up to byte alignment */
111 /* I'm worried about this cast on sizeof(long) != sizeof(uchar *)
112 architectures, but it _should_ work. */
113 for (i = 0; ((unsigned long)buf) & 3; i++)
114 {
115 *buf++ = r;
116 *buf++ = g;
117 *buf++ = b;
118 }
119 #ifndef WORDS_BIGENDIAN
120 v1 = r | (g << 8) | (b << 16) | (r << 24);
121 v3 = (v1 << 8) | b;
122 v2 = (v3 << 8) | g;
123 #else
124 v1 = (r << 24) | (g << 16) | (b << 8) | r;
125 v2 = (v1 << 8) | g;
126 v3 = (v2 << 8) | b;
127 #endif
128 for (; i < n - 3; i += 4)
129 {
130 ((art_u32 *)buf)[0] = v1;
131 ((art_u32 *)buf)[1] = v2;
132 ((art_u32 *)buf)[2] = v3;
133 buf += 12;
134 }
135 /* handle postfix */
136 for (; i < n; i++)
137 {
138 *buf++ = r;
139 *buf++ = g;
140 *buf++ = b;
141 }
142 }
143 }
144 }
145 #endif
146
147 /**
148 * art_rgb_run_alpha: Render semitransparent color over RGB buffer.
149 * @buf: Buffer for rendering.
150 * @r: Red, range 0..255.
151 * @g: Green, range 0..255.
152 * @b: Blue, range 0..255.
153 * @alpha: Alpha, range 0..256.
154 * @n: Number of RGB triples to render.
155 *
156 * Renders a sequential run of solid (@r, @g, @b) color over @buf with
157 * opacity @alpha.
158 **/
159 void
art_rgb_run_alpha(art_u8 * buf,art_u8 r,art_u8 g,art_u8 b,int alpha,int n)160 art_rgb_run_alpha (art_u8 *buf, art_u8 r, art_u8 g, art_u8 b, int alpha, int n)
161 {
162 int i;
163 int v;
164
165 for (i = 0; i < n; i++)
166 {
167 v = *buf;
168 *buf++ = v + (((r - v) * alpha + 0x80) >> 8);
169 v = *buf;
170 *buf++ = v + (((g - v) * alpha + 0x80) >> 8);
171 v = *buf;
172 *buf++ = v + (((b - v) * alpha + 0x80) >> 8);
173 }
174 }
175
176