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: Anssi Hannula <anssi.hannula@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
diff --git a/drivers/usb/input/fixp-arith.h b/drivers/usb/input/fixp-arith.h
index b44d398..ed3d2da 100644
--- a/drivers/usb/input/fixp-arith.h
+++ b/drivers/usb/input/fixp-arith.h
@@ -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 @@
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;