allow inputs to be inverted (#38)

* allow inputs to be inverted

* add inverted and active to the module reference

docs/module_reference.md

@@ -57,10 +57,12 @@ The input module is associated with a digital input pin that is be connected to
 | -------------------- | -------------------------------------- | --------- |
 | `input = Input(pin)` | `pin` is the corresponding GPIO number | `int`     |
 
-| Properties     | Description                           | Data type |
-| -------------- | ------------------------------------- | --------- |
-| `input.level`  | Current signal level (0 or 1)         | `int`     |
-| `input.change` | Level change since last cycle (-1..1) | `int`     |
+| Properties       | Description                           | Data type |
+| ---------------- | ------------------------------------- | --------- |
+| `input.level`    | Current signal level (0 or 1)         | `int`     |
+| `input.change`   | Level change since last cycle (-1..1) | `int`     |
+| `input.inverted` | Inverts the active property if true   | `bool`    |
+| `input.active`   | Current active state of the input     | `bool`    |
 
 | Methods            | Description                        |
 | ------------------ | ---------------------------------- |

main/modules/input.cpp

@@ -5,12 +5,15 @@
 Input::Input(const std::string name) : Module(input, name) {
     this->properties["level"] = std::make_shared<IntegerVariable>();
     this->properties["change"] = std::make_shared<IntegerVariable>();
+    this->properties["inverted"] = std::make_shared<BooleanVariable>();
+    this->properties["active"] = std::make_shared<BooleanVariable>();
 }
 
 void Input::step() {
     const int new_level = this->get_level();
     this->properties.at("change")->integer_value = new_level - this->properties.at("level")->integer_value;
     this->properties.at("level")->integer_value = new_level;
+    this->properties.at("active")->boolean_value = this->properties.at("inverted")->boolean_value ? !new_level : new_level;
     Module::step();
 }