add Chapter12

Chapter12/cpp_hal/hal/gpio/src/gpio.cpp

@@ -0,0 +1,21 @@
+#include <gpio.hpp>
+#include <gpio_interrupt_manager.hpp>
+
+namespace hal {
+
+gpio::gpio(const std::function<void()> & on_press) {
+    on_press_ = on_press;
+    gpio_interrupt_manager::register_interrupt_handler(this);
+}
+
+void gpio::execute_interrupt_handler () const {
+    if(is_interrupt_generated())
+    {
+        clear_interrupt_flag();
+        if(on_press_) {
+            on_press_();
+        }
+    }
+}
+
+};