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_();
+        }
+    }
+}
+
+};

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

@@ -0,0 +1,17 @@
+#include <gpio_interrupt_manager.hpp>
+
+namespace hal {
+
+void gpio_interrupt_manager::register_interrupt_handler(gpio * pin) {
+    gpio_handlers.at(w_idx++) = pin;
+}
+
+void gpio_interrupt_manager::execute_interrupt_handlers() {
+    for(std::size_t i = 0; i < w_idx; i++) {
+        gpio_handlers[i]->execute_interrupt_handler();
+    }
+}
+extern "C" void EXTI4_15_IRQHandler(void) {
+    gpio_interrupt_manager::execute_interrupt_handlers();
+}
+};