diff options
Diffstat (limited to 'include/linux/fixp-arith.h')
-rw-r--r-- | include/linux/fixp-arith.h | 87 |
1 files changed, 87 insertions, 0 deletions
diff --git a/include/linux/fixp-arith.h b/include/linux/fixp-arith.h new file mode 100644 index 000000000000..3089d7382325 --- /dev/null +++ b/include/linux/fixp-arith.h @@ -0,0 +1,87 @@ +#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 <johann.deneux@gmail.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[46] = { + 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, 0x0000 +}; + + +/* 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 = 90 - 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 |