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#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
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