Merge pull request 'fifo enhancement' (#57) from KSat/fsfw:mueller_fifo_enhancement into master

Implements #57

container/FIFO.h

@@ -3,6 +3,11 @@
 
 #include <framework/returnvalues/HasReturnvaluesIF.h>
 
+/**
+ * @brief Simple First-In-First-Out data structure
+ * @tparam T Entry Type
+ * @tparam capacity Maximum capacity
+ */
 template<typename T, uint8_t capacity>
 class FIFO {
 private:
@@ -54,6 +59,21 @@ public:
 			return HasReturnvaluesIF::RETURN_OK;
 		}
 	}
+
+	ReturnValue_t peek(T * value) {
+	    if(empty()) {
+	        return EMPTY;
+	    } else {
+	       *value = data[readIndex];
+	       return HasReturnvaluesIF::RETURN_OK;
+	    }
+	}
+
+	ReturnValue_t pop() {
+		T value;
+		return this->retrieve(&value);
+	}
+
 	static const uint8_t INTERFACE_ID = CLASS_ID::FIFO_CLASS;
 	static const ReturnValue_t FULL = MAKE_RETURN_CODE(1);
 	static const ReturnValue_t EMPTY = MAKE_RETURN_CODE(2);