From 290635b3540b927ffb9f65d1c9d479dad050b21c Mon Sep 17 00:00:00 2001
From: "DrZiplok@gmail.com"
 <DrZiplok@gmail.com@f9c3cf11-9bcb-44bc-f272-b75c42450872>
Date: Mon, 20 Dec 2010 01:52:23 +0000
Subject: [PATCH] Minor code size optimisation; use memset to zero *this rather
 than explicitly assigning zero to the vector elements.  Still not quite
 optimal for matrix3 as it gets three memsets, but still cheaper in terms of
 code size.

git-svn-id: https://arducopter.googlecode.com/svn/trunk@1212 f9c3cf11-9bcb-44bc-f272-b75c42450872
---
 libraries/AP_Math/matrix3.h | 1 +
 libraries/AP_Math/vector2.h | 7 +++----
 libraries/AP_Math/vector3.h | 7 ++++---
 3 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/libraries/AP_Math/matrix3.h b/libraries/AP_Math/matrix3.h
index 51fd144c75..85f4516607 100644
--- a/libraries/AP_Math/matrix3.h
+++ b/libraries/AP_Math/matrix3.h
@@ -42,6 +42,7 @@ public:
 	Vector3<T>	a, b, c;
 
 	// trivial ctor
+	// note that the Vector3 ctor will zero the vector elements
 	Matrix3<T>() {}
 
 	// setting ctor
diff --git a/libraries/AP_Math/vector2.h b/libraries/AP_Math/vector2.h
index 9e12b524bf..e87ac40fcd 100644
--- a/libraries/AP_Math/vector2.h
+++ b/libraries/AP_Math/vector2.h
@@ -30,9 +30,8 @@ struct Vector2
 {
 	T x, y;
 
-
 	// trivial ctor
-	Vector2<T>(): x(0),y(0) {}
+	Vector2<T>() {memset(this, 0, sizeof(*this));}
 
 	// setting ctor
 	Vector2<T>(const T x0, const T y0): x(x0), y(y0) {}
@@ -140,11 +139,11 @@ struct Vector2
 	{   return v * (*this * v)/(v*v);	}
 
 	// computes the angle between 2 arbitrary vectors
-	static inline T angle(const Vector2<T> &v1, const Vector2<T> &v2)
+	T angle(const Vector2<T> &v1, const Vector2<T> &v2)
 	{   return (T)acosf((v1*v2) / (v1.length()*v2.length()));  }
 
 	// computes the angle between 2 normalized arbitrary vectors
-	static inline T angle_normalized(const Vector2<T> &v1, const Vector2<T> &v2)
+	T angle_normalized(const Vector2<T> &v1, const Vector2<T> &v2)
 	{   return (T)acosf(v1*v2);  }
 
 };
diff --git a/libraries/AP_Math/vector3.h b/libraries/AP_Math/vector3.h
index 39d9e31081..214928896a 100644
--- a/libraries/AP_Math/vector3.h
+++ b/libraries/AP_Math/vector3.h
@@ -42,6 +42,7 @@
 #define VECTOR3_H
 
 #include <math.h>
+#include <string.h>
 
 template <typename T>
 class Vector3
@@ -50,7 +51,7 @@ public:
 	T x, y, z;
 
 	// trivial ctor
-	Vector3<T>(): x(0),y(0),z(0) {}
+	Vector3<T>() {memset(this, 0, sizeof(*this));}
 
 	// setting ctor
 	Vector3<T>(const T x0, const T y0, const T z0): x(x0), y(y0), z(z0) {}
@@ -165,11 +166,11 @@ public:
 	{   return v * (*this * v)/(v*v);	}
 
 	// computes the angle between 2 arbitrary vectors
-	static inline T angle(const Vector3<T> &v1, const Vector3<T> &v2)
+	T angle(const Vector3<T> &v1, const Vector3<T> &v2)
 	{   return (T)acosf((v1*v2) / (v1.length()*v2.length()));  }
 
 	// computes the angle between 2 arbitrary normalized vectors
-	static inline T angle_normalized(const Vector3<T> &v1, const Vector3<T> &v2)
+	T angle_normalized(const Vector3<T> &v1, const Vector3<T> &v2)
 	{   return (T)acosf(v1*v2);  }
 
 };