document SaveRestore and InterfaceObject

src/knx/interface_object.cpp

@@ -5,6 +5,10 @@ void InterfaceObject::readPropertyDescription(uint8_t& propertyId, uint8_t& prop
     PropertyDescription* descriptions = propertyDescriptions();
     uint8_t count = propertyCount();
 
+    numberOfElements = 0;
+    if (descriptions == nullptr || count == 0)
+        return;
+
     PropertyDescription* desc = nullptr;
 
     // from KNX spec. 03.03.07 Application Layer (page 56) - 3.4.3.3  A_PropertyDescription_Read-service
@@ -40,4 +44,28 @@ void InterfaceObject::readPropertyDescription(uint8_t& propertyId, uint8_t& prop
         numberOfElements = desc->MaxElements;
         access = desc->Access;
     }
+}
+
+void InterfaceObject::readProperty(PropertyID id, uint32_t start, uint32_t &count, uint8_t *data)
+{
+    count = 0;
+}
+
+void InterfaceObject::writeProperty(PropertyID id, uint8_t start, uint8_t *data, uint8_t count)
+{
+}
+
+uint8_t InterfaceObject::propertySize(PropertyID id)
+{
+    return 0;
+}
+
+uint8_t InterfaceObject::propertyCount()
+{
+    return 0;
+}
+
+PropertyDescription* InterfaceObject::propertyDescriptions()
+{
+    return nullptr;
 }

src/knx/interface_object.h

@@ -4,6 +4,7 @@
 #include "property_types.h"
 #include "save_restore.h"
 
+/** Enum for the type of an interface object. See Section 2.2 at 03_07_03 of knx specification. */
 enum ObjectType
 {
     /** Device object. */
@@ -49,16 +50,78 @@ enum ObjectType
     OT_FILE_SERVER = 13
 };
 
-
+/**
+ * @brief This class represents and interface object. See section 4 of 03_04_01 in the knx specification.
+ */
 class InterfaceObject: public SaveRestore
 {
 public:
+    /**
+     * @brief Destructor
+     */
     virtual ~InterfaceObject() {}
-    virtual void readProperty(PropertyID id, uint32_t start, uint32_t& count, uint8_t* data) = 0;
-    virtual void writeProperty(PropertyID id, uint8_t start, uint8_t* data, uint8_t count) = 0;
-    virtual uint8_t propertySize(PropertyID id) = 0;
+    /**
+     * @brief Read a property of the interface object. See section 4.8.4.2 in 03_04_01 of the knx specification.
+     * 
+     * @param id id of the property to read
+     * 
+     * @param start (for properties with multiple values) at which element should we start
+     * 
+     * @param[in, out] count how many values should be read. If there is a problem (e.g. property does not exist)
+     *        this value is set to 0.
+     * 
+     * @param[out] data The requested data of the property.
+     */
+    virtual void readProperty(PropertyID id, uint32_t start, uint32_t& count, uint8_t* data);
+    /**
+     * @brief Write property of the interface object. If the interface object does not have the property this 
+     * method does nothing. See section 4.8.4.4 in 03_04_01 of the knx specification.
+     * 
+     * @param id id of the property to write
+     * 
+     * @param start (for properties with multiple values) at which element should we start
+     * 
+     * @param count how many values should be written.
+     * 
+     * @param data The data that should be written.
+     */
+    virtual void writeProperty(PropertyID id, uint8_t start, uint8_t* data, uint8_t count);
+    /**
+     * @brief Gets the size of of property in bytes.
+     * 
+     * @param id of the property to get the size of
+     * 
+     * @returns the size in byte or 0 if the interface object does not have the property
+     */
+    virtual uint8_t propertySize(PropertyID id);
+    /**
+     * @brief Read the Description of a property of the interface object. The output parameters are only valid if nuberOfElements is not zero.
+     * 
+     * @param[in,out] propertyId The id of the property of which to read the description of. If this parameter is not zero
+     *        propertyIndex paramter is ignored as input and the corrrect index of the property is written to it. If this 
+     *        parameter is zero the ::PropertyID of the property specified by propertyIndex is written to it.
+     *        
+     * @param[in,out] propertyIndex The index of the property of the interface object of which to read the description of.
+     *        only used for input if propertyId is not set. Otherwise the index of the property specified by propertyId is written to it.
+     *
+     * @param[out] writeEnable Can the property be written to.
+     * 
+     * @param[out] type the ::PropertyDataType of the property
+     * 
+     * @param[out] numberOfElements the number of elements of the property. Zero if the interface object does not have the requested property.
+     * 
+     * @param[out] access the ::AccessLevel necessary to read/write the property. 
+     */
+    
     void readPropertyDescription(uint8_t& propertyId, uint8_t& propertyIndex, bool& writeEnable, uint8_t& type, uint16_t& numberOfElements, uint8_t& access);
 protected:
-    virtual uint8_t propertyCount() = 0;
-    virtual PropertyDescription* propertyDescriptions() = 0;
+    /**
+     * @brief Returns the number of properties the interface object has.
+     */
+    virtual uint8_t propertyCount();
+    /**
+     * @brief Returns a pointer to the first PropertyDescription of the interface object. 
+     * This is used by readPropertyDescription() together with propertyCount().
+     */
+    virtual PropertyDescription* propertyDescriptions();
 };

src/knx/property_types.h

@@ -11,6 +11,7 @@
 
 #include <stdint.h>
 
+/** The data type of a property. */
 enum PropertyDataType
 {
     PDT_CONTROL            = 0x00, //!< length: 1 read, 10 write
@@ -168,6 +169,7 @@ enum ErrorCode
     E_GO_TYPE_TOO_BIG = 18
 };
 
+/** The access level necessary to read a property of an interface object. */
 enum AccessLevel
 {
     ReadLv0 = 0x00,

src/knx/save_restore.h

@@ -2,7 +2,7 @@
 #include <stdint.h>
 
 /**
- *@brief Interface for classes that can save and restore data from a buffer. 
+ * @brief Interface for classes that can save and restore data from a buffer. 
  */
 class SaveRestore
 {