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 <[email protected]> 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