README: updated UI and control information

README.md

@@ -17,7 +17,10 @@ This is a personal project for fun and to experience emulating hardware and conn
   - [x] Mapper 2
   - [x] Mapper 3
   - [x] Mapper 4
+  - [ ] Mapper 5 (Milestone)
+  - [ ] Mapper 6
   - [x] Mapper 7
+  - [ ] Mapper 8
   - [x] Mapper 9
 - [ ] Audio Processing Unit:
   - [x] 2 Pulse wave(square)
@@ -28,6 +31,92 @@ This is a personal project for fun and to experience emulating hardware and conn
 - [x] Controller:
   controllable using the keyboard and controller (tested with PS4 controller)
 
+### Interfaces
+One advantage of this emulator is the great abstraction, for example, adding UI
+handlers for the emulator is very easy and straight forward. All you have to do
+is to write a [`UiProvider`](./nes_ui_base/src/lib.rs), and simply
+use it with [`NES`](./nes_ui_base/src/nes.rs) like so:
+```rust
+use nes_ui_base::nes::NES;
+
+// Provider implement trait `UiProvider`
+let mut nes = NES::new("path/to/rom.nes", Provider {})?;
+
+nes.run();
+```
+
+Using this design, I have implemented some providers which have
+different purposes:
+
+#### SFML
+![screenshot SFML](images/SFML_UI.png)
+
+[SFML][SFML] is a game development UI library, it has a good and
+easy to use API and is the most performing UI in the list.
+
+#### Advantages
+1. Designed for Canvas and raw drawing, which makes it faster.
+2. Has support for gamepad (only tested with PS4).
+
+#### GTK
+![screenshot SFML](images/GTK_UI.png)
+
+[GTK][GTK] is a casual GUI library that is used to make all kinds
+of applications and not designed for games.
+
+The reason I chose to go with it is for future plans to add a
+debugger, which would be a lot easier to add in this UI compared
+to [SFML](#sfml)
+
+#### Advantages
+1. Ability to add buttons and menus which enable easier integration
+   for debuggers and anything similar.
+#### Disadvantages
+1. Does not offer gamepad support, but it can be added through
+   other external libraries.
+
+#### TUI
+[![TUI demo](https://img.youtube.com/vi/cMO89-Xljr8/0.jpg)](https://www.youtube.com/watch?v=cMO89-Xljr8)
+
+This is just for fun, but it is actually working way better than
+I expected. Check the demo.
+
+I used [gilrs][gilrs] for gamepad support and its working very
+nicely, keyboard on the other hand is not very responsive, so it
+is advised to use gamepad. Also since this uses one character for
+each pixel, it is advised to use the smallest font size your
+terminal emulator supports. Have fun.
+
+### Controls
+In all the UI providers I followed the same controlling scheme:
+
+#### Keyboard
+| keyboard | nes controller |
+| -------- | -------------- |
+| J | B |
+| K | A |
+| U | Select |
+| I | Start |
+| W | Up |
+| S | Down |
+| A | Left |
+| D | Right |
+
+#### Gamepad
+| gamepad (PS4) | nes controller |
+| -------- | -------------- |
+| X | B |
+| O | A |
+| Select | Select |
+| Start | Start |
+| Button Up | Up |
+| Button Down | Down |
+| Button Left | Left |
+| Button Right | Right |
+
+For now its static, and there is no way to change it except for
+doing it in the code, TODO later.
+
 ### References
 Most of the documentation for NES components can be found in the [NES dev wiki](http://wiki.nesdev.com/w/index.php/Nesdev_Wiki)
 
@@ -38,3 +127,6 @@ For the CPU(6502), [this](https://www.masswerk.at/6502/6502_instruction_set.html
 
 [NES-wiki]: https://en.wikipedia.org/wiki/Nintendo_Entertainment_System
 [Rust]: https://www.rust-lang.org/
+[SFML]: https://www.sfml-dev.org/
+[GTK]: https://www.gtk.org/
+[gilrs]: https://gitlab.com/gilrs-project/gilrs