| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | #ifndef _FIXP_ARITH_H |
| 2 | #define _FIXP_ARITH_H |
| 3 | |
| 4 | /* |
| 5 | * $$ |
| 6 | * |
| 7 | * Simplistic fixed-point arithmetics. |
| 8 | * Hmm, I'm probably duplicating some code :( |
| 9 | * |
| 10 | * Copyright (c) 2002 Johann Deneux |
| 11 | */ |
| 12 | |
| 13 | /* |
| 14 | * This program is free software; you can redistribute it and/or modify |
| 15 | * it under the terms of the GNU General Public License as published by |
| 16 | * the Free Software Foundation; either version 2 of the License, or |
| 17 | * (at your option) any later version. |
| 18 | * |
| 19 | * This program is distributed in the hope that it will be useful, |
| 20 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 22 | * GNU General Public License for more details. |
| 23 | * |
| 24 | * You should have received a copy of the GNU General Public License |
| 25 | * along with this program; if not, write to the Free Software |
| 26 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
| 27 | * |
| 28 | * Should you need to contact me, the author, you can do so by |
| 29 | * e-mail - mail your message to <deneux@ifrance.com> |
| 30 | */ |
| 31 | |
| 32 | #include <linux/types.h> |
| 33 | |
| 34 | // The type representing fixed-point values |
| 35 | typedef s16 fixp_t; |
| 36 | |
| 37 | #define FRAC_N 8 |
| 38 | #define FRAC_MASK ((1<<FRAC_N)-1) |
| 39 | |
| 40 | // Not to be used directly. Use fixp_{cos,sin} |
| 41 | static fixp_t cos_table[45] = { |
| 42 | 0x0100, 0x00FF, 0x00FF, 0x00FE, 0x00FD, 0x00FC, 0x00FA, 0x00F8, |
| 43 | 0x00F6, 0x00F3, 0x00F0, 0x00ED, 0x00E9, 0x00E6, 0x00E2, 0x00DD, |
| 44 | 0x00D9, 0x00D4, 0x00CF, 0x00C9, 0x00C4, 0x00BE, 0x00B8, 0x00B1, |
| 45 | 0x00AB, 0x00A4, 0x009D, 0x0096, 0x008F, 0x0087, 0x0080, 0x0078, |
| 46 | 0x0070, 0x0068, 0x005F, 0x0057, 0x004F, 0x0046, 0x003D, 0x0035, |
| 47 | 0x002C, 0x0023, 0x001A, 0x0011, 0x0008 |
| 48 | }; |
| 49 | |
| 50 | |
| 51 | /* a: 123 -> 123.0 */ |
| 52 | static inline fixp_t fixp_new(s16 a) |
| 53 | { |
| 54 | return a<<FRAC_N; |
| 55 | } |
| 56 | |
| 57 | /* a: 0xFFFF -> -1.0 |
| 58 | 0x8000 -> 1.0 |
| 59 | 0x0000 -> 0.0 |
| 60 | */ |
| 61 | static inline fixp_t fixp_new16(s16 a) |
| 62 | { |
| 63 | return ((s32)a)>>(16-FRAC_N); |
| 64 | } |
| 65 | |
| 66 | static inline fixp_t fixp_cos(unsigned int degrees) |
| 67 | { |
| 68 | int quadrant = (degrees / 90) & 3; |
| 69 | unsigned int i = degrees % 90; |
| 70 | |
| 71 | if (quadrant == 1 || quadrant == 3) { |
| 72 | i = 89 - i; |
| 73 | } |
| 74 | |
| 75 | i >>= 1; |
| 76 | |
| 77 | return (quadrant == 1 || quadrant == 2)? -cos_table[i] : cos_table[i]; |
| 78 | } |
| 79 | |
| 80 | static inline fixp_t fixp_sin(unsigned int degrees) |
| 81 | { |
| 82 | return -fixp_cos(degrees + 90); |
| 83 | } |
| 84 | |
| 85 | static inline fixp_t fixp_mult(fixp_t a, fixp_t b) |
| 86 | { |
| 87 | return ((s32)(a*b))>>FRAC_N; |
| 88 | } |
| 89 | |
| 90 | #endif |