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1 | #ifndef _FIXP_ARITH_H |
2 | #define _FIXP_ARITH_H |
3 | |
4 | /* |
5 | * 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 <johann.deneux@gmail.com> |
28 | */ |
29 | |
30 | #include <linux/types.h> |
31 | |
32 | /* The type representing fixed-point values */ |
33 | typedef s16 fixp_t; |
34 | |
35 | #define FRAC_N 8 |
36 | #define FRAC_MASK ((1<<FRAC_N)-1) |
37 | |
38 | /* Not to be used directly. Use fixp_{cos,sin} */ |
39 | static const fixp_t cos_table[46] = { |
40 | 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, |
45 | 0x002C, 0x0023, 0x001A, 0x0011, 0x0008, 0x0000 |
46 | }; |
47 | |
48 | |
49 | /* a: 123 -> 123.0 */ |
50 | static 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 | */ |
59 | static inline fixp_t fixp_new16(s16 a) |
60 | { |
61 | return ((s32)a)>>(16-FRAC_N); |
62 | } |
63 | |
64 | static inline fixp_t fixp_cos(unsigned int degrees) |
65 | { |
66 | int quadrant = (degrees / 90) & 3; |
67 | unsigned int i = degrees % 90; |
68 | |
69 | if (quadrant == 1 || quadrant == 3) |
70 | i = 90 - i; |
71 | |
72 | i >>= 1; |
73 | |
74 | return (quadrant == 1 || quadrant == 2)? -cos_table[i] : cos_table[i]; |
75 | } |
76 | |
77 | static inline fixp_t fixp_sin(unsigned int degrees) |
78 | { |
79 | return -fixp_cos(degrees + 90); |
80 | } |
81 | |
82 | static inline fixp_t fixp_mult(fixp_t a, fixp_t b) |
83 | { |
84 | return ((s32)(a*b))>>FRAC_N; |
85 | } |
86 | |
87 | #endif |
88 |
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