5 * Simplistic fixed-point arithmetics.
6 * Hmm, I'm probably duplicating some code :(
8 * Copyright (c) 2002 Johann Deneux
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.
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.
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
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>
30 #include <linux/types.h>
32 /* The type representing fixed-point values */
36 #define FRAC_MASK ((1<<FRAC_N)-1)
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
50 static inline fixp_t
fixp_new(s16 a
)
59 static inline fixp_t
fixp_new16(s16 a
)
61 return ((s32
)a
)>>(16-FRAC_N
);
64 static inline fixp_t
fixp_cos(unsigned int degrees
)
66 int quadrant
= (degrees
/ 90) & 3;
67 unsigned int i
= degrees
% 90;
69 if (quadrant
== 1 || quadrant
== 3)
74 return (quadrant
== 1 || quadrant
== 2)? -cos_table
[i
] : cos_table
[i
];
77 static inline fixp_t
fixp_sin(unsigned int degrees
)
79 return -fixp_cos(degrees
+ 90);
82 static inline fixp_t
fixp_mult(fixp_t a
, fixp_t b
)
84 return ((s32
)(a
*b
))>>FRAC_N
;