GPIO hal prototype (#9)

* gpio hal prototype
* Example gpio hal usage
* Use uint8_t for GPIO enums

src/hal/gpio.h

@@ -0,0 +1,76 @@
+#include <inttypes.h>
+#include <avr/io.h>
+
+namespace hal {
+namespace gpio {
+
+    struct GPIO_TypeDef {
+        volatile uint8_t PINx;
+        volatile uint8_t DDRx;
+        volatile uint8_t PORTx;
+    };
+
+    enum class Mode : uint8_t {
+        input = 0,
+        output,
+    };
+
+    enum class Pull : uint8_t {
+        none = 0,
+        up,
+        down, //not available on the AVR
+    };
+
+    enum class Level : uint8_t {
+        low = 0,
+        high,
+    };
+
+    struct GPIO_InitTypeDef {
+        Mode mode;
+        Pull pull;
+        Level level;
+        inline GPIO_InitTypeDef()
+            : mode(Mode::input)
+            , pull(Pull::none) {};
+        inline GPIO_InitTypeDef(Mode mode, Pull pull)
+            : mode(mode)
+            , pull(pull) {};
+        inline GPIO_InitTypeDef(Mode mode, Level level)
+            : mode(mode)
+            , level(level) {};
+    };
+
+    inline void WritePin(GPIO_TypeDef *const port, const uint8_t pin, Level level) {
+        if (level == Level::high)
+            port->PORTx |= (1 << pin);
+        else
+            port->PORTx &= ~(1 << pin);
+    }
+
+    inline Level ReadPin(GPIO_TypeDef *const port, const uint8_t pin) {
+        return (Level)(port->PINx & (1 << pin));
+    }
+
+    inline void TogglePin(GPIO_TypeDef *const port, const uint8_t pin) {
+        port->PINx |= (1 << pin);
+    }
+
+    inline void Init(GPIO_TypeDef *const port, const uint8_t pin, GPIO_InitTypeDef GPIO_Init) {
+        if (GPIO_Init.mode == Mode::output) {
+            WritePin(port, pin, GPIO_Init.level);
+            port->DDRx |= (1 << pin);
+        } else {
+            port->DDRx &= ~(1 << pin);
+            WritePin(port, pin, (Level)GPIO_Init.pull);
+        }
+    }
+
+}
+}
+
+#define GPIOB ((hal::gpio::GPIO_TypeDef *)&PINB)
+#define GPIOC ((hal::gpio::GPIO_TypeDef *)&PINC)
+#define GPIOD ((hal::gpio::GPIO_TypeDef *)&PIND)
+#define GPIOE ((hal::gpio::GPIO_TypeDef *)&PINE)
+#define GPIOF ((hal::gpio::GPIO_TypeDef *)&PINF)

src/hal/pins.h

@@ -5,9 +5,7 @@
 namespace hal {
 namespace pins {
 
-    /// pin access routines
-    void WritePin(uint8_t pin, uint8_t value);
-    uint8_t ReadPin(uint8_t pin);
+    /// pin definitions
 
 } // namespace pins
 } // namespace hal

src/main.cpp

@@ -1,8 +1,11 @@
 #include "logic/mm_control.h"
+#include "hal/gpio.h"
 
 /// One-time setup of HW and SW components
 /// Called before entering the loop() function
 void setup(){
+    using namespace hal::gpio;
+    hal::gpio::Init(GPIOB, 1, GPIO_InitTypeDef(Mode::output, Level::low));
 
 }
 
@@ -27,6 +30,11 @@ void loop(){
 int main() {
     setup();
     for(;;){
+        using namespace hal::gpio;
+        WritePin(GPIOB, 5, Level::low);
+        TogglePin(GPIOB, 6);
+        if (hal::gpio::ReadPin(GPIOB, 7) == hal::gpio::Level::low)
+            break;
         loop();
     }
     return 0;