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Linus Torvalds1da177e2005-04-16 15:20:36 -07001#ifndef _FIXP_ARITH_H
2#define _FIXP_ARITH_H
3
4/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07005 * Simplistic fixed-point arithmetics.
6 * Hmm, I'm probably duplicating some code :(
7 *
8 * Copyright (c) 2002 Johann Deneux
9 */
10
11/*
12 * This program is free software; you can redistribute it and/or modify
13 * it under the terms of the GNU General Public License as published by
14 * the Free Software Foundation; either version 2 of the License, or
15 * (at your option) any later version.
16 *
17 * This program is distributed in the hope that it will be useful,
18 * but WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 * GNU General Public License for more details.
21 *
22 * You should have received a copy of the GNU General Public License
23 * along with this program; if not, write to the Free Software
24 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
25 *
26 * Should you need to contact me, the author, you can do so by
27 * e-mail - mail your message to <deneux@ifrance.com>
28 */
29
30#include <linux/types.h>
31
Anssi Hannula3cbd5b32006-06-05 00:18:43 -040032/* The type representing fixed-point values */
Linus Torvalds1da177e2005-04-16 15:20:36 -070033typedef s16 fixp_t;
34
35#define FRAC_N 8
36#define FRAC_MASK ((1<<FRAC_N)-1)
37
Anssi Hannula3cbd5b32006-06-05 00:18:43 -040038/* Not to be used directly. Use fixp_{cos,sin} */
39static const fixp_t cos_table[46] = {
Linus Torvalds1da177e2005-04-16 15:20:36 -070040 0x0100, 0x00FF, 0x00FF, 0x00FE, 0x00FD, 0x00FC, 0x00FA, 0x00F8,
41 0x00F6, 0x00F3, 0x00F0, 0x00ED, 0x00E9, 0x00E6, 0x00E2, 0x00DD,
42 0x00D9, 0x00D4, 0x00CF, 0x00C9, 0x00C4, 0x00BE, 0x00B8, 0x00B1,
43 0x00AB, 0x00A4, 0x009D, 0x0096, 0x008F, 0x0087, 0x0080, 0x0078,
44 0x0070, 0x0068, 0x005F, 0x0057, 0x004F, 0x0046, 0x003D, 0x0035,
Anssi Hannula3cbd5b32006-06-05 00:18:43 -040045 0x002C, 0x0023, 0x001A, 0x0011, 0x0008, 0x0000
Linus Torvalds1da177e2005-04-16 15:20:36 -070046};
47
48
49/* a: 123 -> 123.0 */
50static inline fixp_t fixp_new(s16 a)
51{
52 return a<<FRAC_N;
53}
54
55/* a: 0xFFFF -> -1.0
56 0x8000 -> 1.0
57 0x0000 -> 0.0
58*/
59static inline fixp_t fixp_new16(s16 a)
60{
61 return ((s32)a)>>(16-FRAC_N);
62}
63
64static inline fixp_t fixp_cos(unsigned int degrees)
65{
66 int quadrant = (degrees / 90) & 3;
67 unsigned int i = degrees % 90;
68
Anssi Hannula3cbd5b32006-06-05 00:18:43 -040069 if (quadrant == 1 || quadrant == 3)
70 i = 90 - i;
Linus Torvalds1da177e2005-04-16 15:20:36 -070071
72 i >>= 1;
73
74 return (quadrant == 1 || quadrant == 2)? -cos_table[i] : cos_table[i];
75}
76
77static inline fixp_t fixp_sin(unsigned int degrees)
78{
79 return -fixp_cos(degrees + 90);
80}
81
82static inline fixp_t fixp_mult(fixp_t a, fixp_t b)
83{
84 return ((s32)(a*b))>>FRAC_N;
85}
86
87#endif