From: Anssi Hannula <anssi.hannula@gmail.com>
Date: Mon, 5 Jun 2006 04:18:43 +0000 (-0400)
Subject: Input: fix accuracy of fixp-arith.h
X-Git-Tag: v2.6.18-rc1~604^2~15
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3cbd5b32cb625f5c0f1b1476d154fac873dd49ce;p=linux-2.6

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 b44d398de0..ed3d2da0c4 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 @@ 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;