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awilliam
GitHub Repository: awilliam/linux-vfio
 Path: blob/master/drivers/input/fixp-arith.h
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#ifndef _FIXP_ARITH_H

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#define _FIXP_ARITH_H

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/*

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 * Simplistic fixed-point arithmetics.

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 * Hmm, I'm probably duplicating some code :(

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 *

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 * Copyright (c) 2002 Johann Deneux

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 */

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/*

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 * This program is free software; you can redistribute it and/or modify

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 * it under the terms of the GNU General Public License as published by

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 * the Free Software Foundation; either version 2 of the License, or

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 * (at your option) any later version.

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 *

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 * This program is distributed in the hope that it will be useful,

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 * but WITHOUT ANY WARRANTY; without even the implied warranty of

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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

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 * GNU General Public License for more details.

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 *

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 * You should have received a copy of the GNU General Public License

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 * along with this program; if not, write to the Free Software

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 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA

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 *

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 * Should you need to contact me, the author, you can do so by

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 * e-mail - mail your message to <[email protected]>

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 */

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#include <linux/types.h>

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/* The type representing fixed-point values */

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typedef s16 fixp_t;

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#define FRAC_N 8

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#define FRAC_MASK ((1<<FRAC_N)-1)

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/* Not to be used directly. Use fixp_{cos,sin} */

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static const fixp_t cos_table[46] = {

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	0x0100,	0x00FF,	0x00FF,	0x00FE,	0x00FD,	0x00FC,	0x00FA,	0x00F8,

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	0x00F6,	0x00F3,	0x00F0,	0x00ED,	0x00E9,	0x00E6,	0x00E2,	0x00DD,

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	0x00D9,	0x00D4,	0x00CF,	0x00C9,	0x00C4,	0x00BE,	0x00B8,	0x00B1,

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	0x00AB,	0x00A4,	0x009D,	0x0096,	0x008F,	0x0087,	0x0080,	0x0078,

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	0x0070,	0x0068,	0x005F,	0x0057,	0x004F,	0x0046,	0x003D,	0x0035,

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	0x002C,	0x0023,	0x001A,	0x0011,	0x0008, 0x0000

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};

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/* a: 123 -> 123.0 */

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static inline fixp_t fixp_new(s16 a)

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{

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	return a<<FRAC_N;

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}

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/* a: 0xFFFF -> -1.0

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      0x8000 -> 1.0

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      0x0000 -> 0.0

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*/

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static inline fixp_t fixp_new16(s16 a)

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{

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	return ((s32)a)>>(16-FRAC_N);

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}

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static inline fixp_t fixp_cos(unsigned int degrees)

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{

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	int quadrant = (degrees / 90) & 3;

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	unsigned int i = degrees % 90;

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	if (quadrant == 1 || quadrant == 3)

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		i = 90 - i;

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	i >>= 1;

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	return (quadrant == 1 || quadrant == 2)? -cos_table[i] : cos_table[i];

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}

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static inline fixp_t fixp_sin(unsigned int degrees)

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{

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	return -fixp_cos(degrees + 90);

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}

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static inline fixp_t fixp_mult(fixp_t a, fixp_t b)

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{

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	return ((s32)(a*b))>>FRAC_N;

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}

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#endif

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