Save AP_Var's initial value as a default value, and add a function for restoring the default value.

Fix the AP_Var::lookup cache, which was very busted.

git-svn-id: https://arducopter.googlecode.com/svn/trunk@1448 f9c3cf11-9bcb-44bc-f272-b75c42450872

libraries/AP_Common/AP_Var.cpp

@@ -11,9 +11,11 @@
 
 #include "AP_Var.h"
 
-const AP_Float	AP_GainUnity(1.0);
-const AP_Float	AP_GainNegativeUnity(-1.0);
-const AP_Float	AP_Zero(0);
+// Global constants exported
+//
+AP_Float	AP_FloatUnity(1.0);
+AP_Float	AP_FloatNegativeUnity(-1.0);
+AP_Float	AP_FloatZero(0);
 
 // Constructor
 //
@@ -24,11 +26,12 @@ AP_Var::AP_Var(AP_VarAddress address,
 				   _name(name),
 				   _scope(scope)
 {
-	// if the variable is interesting, link it into the list
-	if (_name || (_address != AP_VarNoAddress)) {
-		_link = _variables;
-		_variables = this;
-	}
+	// link the variable into the list of known variables
+	_link = _variables;
+	_variables = this;
+
+	// reset the lookup cache
+	_lookupHintIndex = 0;
 }
 
 // Destructor
@@ -37,30 +40,36 @@ AP_Var::AP_Var(AP_VarAddress address,
 //
 AP_Var::~AP_Var(void)
 {
-	AP_Var	*p;
+	// if we are at the head of the list - for variables
+	// recently constructed this is usually the case
+	if (_variables == this) {
+		// remove us from the head of the list
+		_variables = _link;
 
-	// only do this for variables that were considered interesting
-	if (_name || (_address != AP_VarNoAddress)) {
-		// if we are at the head of the list - for variables
-		// recently constructed this is usually the case
-		if (_variables == this) {
-			// remove us from the head of the list
-			_variables = _link;
-		} else {
-			// traverse the list looking for the entry that points to us
-			p = _variables;
-			while (p) {
-				// is it pointing at us?
-				if (p->_link == this) {
-					// make it point at what we point at, and done
-					p->_link = _link;
-					break;
-				}
-				// try the next one
-				p = p->_link;
+	} else {
+		// traverse the list looking for the entry that points to us
+		AP_Var	*p = _variables;
+
+		while (p) {
+			// is it pointing at us?
+			if (p->_link == this) {
+				// make it point at what we point at, and done
+				p->_link = _link;
+				break;
 			}
+			// try the next one
+			p = p->_link;
 		}
 	}
+
+	// reset the lookup cache
+	_lookupHintIndex = 0;
+}
+
+void
+AP_Var::set_default(void)
+{
+	// Default implementation of ::set_default does nothing
 }
 
 // Copy the variable name to the provided buffer.
@@ -172,12 +181,12 @@ AP_Var::lookup(int index)
 	}
 
 	// search
-	while (index-- && p)				// count until we hit the index or the end of the list
+	while (i-- && p)					// count until we hit the index or the end of the list
 		p = p->_link;
 
 	// update the cache on hit
 	if (p) {
-		_lookupHintIndex = i;
+		_lookupHintIndex = index;
 		_lookupHint = p;
 	}
 

libraries/AP_Common/AP_Var.h

@@ -65,12 +65,18 @@ public:
 
 	/// Destructor
 	///
-	/// Note that the linked-list removal can be inefficient when named variables
+	/// Note that the linked-list removal can be inefficient when variables
 	/// are destroyed in an order other than the reverse of the order in which
-	/// they are created.
+	/// they are created.  This is not a major issue for variables created
+	/// and destroyed automatically at block boundaries, and the creation and
+	/// destruction of variables by hand is generally discouraged.
 	///
 	~AP_Var(void);
 
+	/// Set the variable to its default value
+	///
+	virtual void	set_default(void);
+
 	/// Copy the variable's name, prefixed by any parent class names, to a buffer.
 	///
 	/// If the variable has no name, the buffer will contain an empty string.
@@ -224,12 +230,13 @@ public:
 	/// @param	name			An optional name by which the variable may be known.
 	/// @param	varClass		An optional class that the variable may be a member of.
 	///
-	AP_VarT<T>(T initialValue			= 0,
+	AP_VarT<T>(T defaultValue			= 0,
 	          AP_VarAddress address		= AP_VarNoAddress,
 	          const prog_char *name		= NULL,
 	          AP_VarScope *scope		= NULL) :
 				  AP_Var(address, name, scope),
-				  _value(initialValue)
+				  _value(defaultValue),
+				  _defaultValue(defaultValue)
 	{
 	}
 
@@ -249,6 +256,9 @@ public:
 		return sizeof(T);
 	}
 
+	/// Restore the variable to its default value
+	virtual void			set_default(void) { _value = _defaultValue; }
+
 	/// Value getter
 	///
 	T						get(void) const { return _value; }
@@ -267,11 +277,12 @@ public:
 	///
 	AP_VarT<T>& operator=(AP_VarT<T>& v)	{ return v; }
 
-	/// Copy assignment from
+	/// Copy assignment from T
 	AP_VarT<T>& operator=(T v)				{ _value = v; return *this; }
 
 protected:
 	T				_value;
+	T				_defaultValue;
 };
 
 
@@ -297,11 +308,11 @@ class AP_Float16 : public AP_Float
 public:
 	/// Constructor mimics AP_Float::AP_Float()
 	///
-	AP_Float16(float initialValue			= 0,
+	AP_Float16(float defaultValue			= 0,
 	           AP_VarAddress address		= AP_VarNoAddress,
 	           const prog_char *name		= NULL,
 	           AP_VarScope *scope		= NULL) :
-	        	   AP_Float(initialValue, address, name, scope)
+	        	   AP_Float(defaultValue, address, name, scope)
 	{
 	}
 
@@ -332,8 +343,11 @@ public:
 };
 
 /// Some convenient constant AP_Vars.
-extern const AP_Float		AP_FloatUnity;
-extern const AP_Float		AP_FloatNegativeUnity;
-extern const AP_Float		AP_FloatZero;
+///
+/// @todo	Work out why these can't be const and fix if possible.
+///
+extern AP_Float		AP_FloatUnity;
+extern AP_Float		AP_FloatNegativeUnity;
+extern AP_Float		AP_FloatZero;
 
 #endif // AP_Var_H