dbus-top: initial commits

This commit covers the basic functionalities of the dbus-top tool.

The UI is divided into 3 windows as follows:

  +--------------------------+  Window list
  |         Window A         |  A: Summary statistics
  +------------+-------------+  B: Sensor list or detail
  |  Window B  |   Window C  |  C: Detailed statistics
  +------------+-------------+

To navigate the UI:
* Use tab to navigate each window

When a window is highlighted:
  In Window B:
  * Press esc key 3 times to leave the current sensor selection

  In Window C:
  * Press [Enter] to show/hide pop-up menu for column selectio
  * Press [Left]  to move highlight cursor to the left
  * Press [Right] to move highlight cursor to the right
  * Press [A] to sort by the highlighted column in ascending order
  * Press [D] to sort by the highlighted column in descending order

To add recipe to Yocto and build the recipe:
1) Copy and paste the content of the .bb file into a folder that can be
   detected by bitbake, such as meta-phosphor/recipes-phosphor/ipmi.
2) run "devtool modify -n dbus-top (path_to_openbmc_tools)/dbus-top/".

Signed-off-by: Adedeji Adebisi <adedejiadebisi01@gmail.com>
Change-Id: Id58ba30b815cfd9d18f54cf477d749dbdbc4545b
diff --git a/dbus-top/main.hpp b/dbus-top/main.hpp
new file mode 100644
index 0000000..91c07da
--- /dev/null
+++ b/dbus-top/main.hpp
@@ -0,0 +1,37 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#pragma once
+
+#include "bargraph.hpp"
+
+#include <ncurses.h>
+
+#include <string>
+
+const int INVALID = -999; // Constant indicating invalid indices
+struct Rect
+{
+    int x, y, w, h; // X, Y, Width, Height
+    Rect(int _x, int _y, int _w, int _h) : x(_x), y(_y), w(_w), h(_h)
+    {}
+    Rect() : x(0), y(0), w(1), h(1)
+    {}
+};
+
+int DrawTextWithWidthLimit(WINDOW* win, std::string txt, int y, int x,
+                           int width, const std::string& delimiters);
+std::string FloatToString(float value);
+template <typename T>
+void HistoryBarGraph(WINDOW* win, const Rect& rect, BarGraph<T>* bargraph);