| #ifndef _FIXP_ARITH_H |
| #define _FIXP_ARITH_H |
| |
| /* |
| * $$ |
| * |
| * Simplistic fixed-point arithmetics. |
| * Hmm, I'm probably duplicating some code :( |
| * |
| * Copyright (c) 2002 Johann Deneux |
| */ |
| |
| /* |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License as published by |
| * the Free Software Foundation; either version 2 of the License, or |
| * (at your option) any later version. |
| * |
| * This program is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| * GNU General Public License for more details. |
| * |
| * You should have received a copy of the GNU General Public License |
| * along with this program; if not, write to the Free Software |
| * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
| * |
| * Should you need to contact me, the author, you can do so by |
| * e-mail - mail your message to <deneux@ifrance.com> |
| */ |
| |
| #include <linux/types.h> |
| |
| // The type representing fixed-point values |
| typedef s16 fixp_t; |
| |
| #define FRAC_N 8 |
| #define FRAC_MASK ((1<<FRAC_N)-1) |
| |
| // Not to be used directly. Use fixp_{cos,sin} |
| static const fixp_t cos_table[45] = { |
| 0x0100, 0x00FF, 0x00FF, 0x00FE, 0x00FD, 0x00FC, 0x00FA, 0x00F8, |
| 0x00F6, 0x00F3, 0x00F0, 0x00ED, 0x00E9, 0x00E6, 0x00E2, 0x00DD, |
| 0x00D9, 0x00D4, 0x00CF, 0x00C9, 0x00C4, 0x00BE, 0x00B8, 0x00B1, |
| 0x00AB, 0x00A4, 0x009D, 0x0096, 0x008F, 0x0087, 0x0080, 0x0078, |
| 0x0070, 0x0068, 0x005F, 0x0057, 0x004F, 0x0046, 0x003D, 0x0035, |
| 0x002C, 0x0023, 0x001A, 0x0011, 0x0008 |
| }; |
| |
| |
| /* a: 123 -> 123.0 */ |
| static inline fixp_t fixp_new(s16 a) |
| { |
| return a<<FRAC_N; |
| } |
| |
| /* a: 0xFFFF -> -1.0 |
| 0x8000 -> 1.0 |
| 0x0000 -> 0.0 |
| */ |
| static inline fixp_t fixp_new16(s16 a) |
| { |
| return ((s32)a)>>(16-FRAC_N); |
| } |
| |
| static inline fixp_t fixp_cos(unsigned int degrees) |
| { |
| int quadrant = (degrees / 90) & 3; |
| unsigned int i = degrees % 90; |
| |
| if (quadrant == 1 || quadrant == 3) { |
| i = 89 - i; |
| } |
| |
| i >>= 1; |
| |
| return (quadrant == 1 || quadrant == 2)? -cos_table[i] : cos_table[i]; |
| } |
| |
| static inline fixp_t fixp_sin(unsigned int degrees) |
| { |
| return -fixp_cos(degrees + 90); |
| } |
| |
| static inline fixp_t fixp_mult(fixp_t a, fixp_t b) |
| { |
| return ((s32)(a*b))>>FRAC_N; |
| } |
| |
| #endif |