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Input: fix accuracy of fixp-arith.h

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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: Anssi Hannula <anssi.hannula@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
This commit is contained in:
Anssi Hannula 2006-06-05 00:18:43 -04:00 committed by Dmitry Torokhov
parent fe65b97a58
commit 3cbd5b32cb
1 changed files with 6 additions and 9 deletions
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15
drivers/usb/input/fixp-arith.h
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@ -2,8 +2,6 @@
#define _FIXP_ARITH_H
/*
* $$
*
* Simplistic fixed-point arithmetics.
* Hmm, I'm probably duplicating some code :(
*
@ -31,20 +29,20 @@
#include <linux/types.h>
// The type representing fixed-point values
/* 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[45] = {
/* 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
0x002C, 0x0023, 0x001A, 0x0011, 0x0008, 0x0000
};
@ -68,9 +66,8 @@ 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 = 89 - i;
}
if (quadrant == 1 || quadrant == 3)
i = 90 - i;
i >>= 1;