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Commit 3cbd5b32 authored by Anssi Hannula's avatar Anssi Hannula Committed by Dmitry Torokhov
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Input: fix accuracy of fixp-arith.h 



Add the value of cos(90) = 0 to the table.  This also moves the results so
that sin(x) == sin(180-x) is true as expected.

Signed-off-by: default avatarAnssi Hannula <anssi.hannula@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarDmitry Torokhov <dtor@mail.ru>
parent fe65b97a

drivers/usb/input/fixp-arith.h

+6 −9
Original line number Original line Diff line number Diff line
@@ -2,8 +2,6 @@ 
#define _FIXP_ARITH_H

#define _FIXP_ARITH_H





/*

/*

 * $$

 *

 * Simplistic fixed-point arithmetics.

 * Simplistic fixed-point arithmetics.

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

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

 *

 *
@@ -31,20 +29,20 @@ 




#include <linux/types.h>

#include <linux/types.h>





// The type representing fixed-point values

/* The type representing fixed-point values */

typedef s16 fixp_t;

typedef s16 fixp_t;





#define FRAC_N 8

#define FRAC_N 8

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

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





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

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

static const fixp_t cos_table[45] = {

static const fixp_t cos_table[46] = {

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

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

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

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

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

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

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

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

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

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

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

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

};

};
@@ -68,9 +66,8 @@ static inline fixp_t fixp_cos(unsigned int degrees) 
	int quadrant = (degrees / 90) & 3;

	int quadrant = (degrees / 90) & 3;

	unsigned int i = degrees % 90;

	unsigned int i = degrees % 90;





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

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

		i = 89 - i;

		i = 90 - i;

	}





	i >>= 1;

	i >>= 1;