Improve GPIO code

- Add CPU_GPIO_TogglePinState.
- Implemented it at platform level (API exists for all platforms except ESP32 on which it was done with the usual approach read-toggle-write).
- Rework code at GpioPin::Toggle to use this.
- Rework code at GpioPin::Toggle and GpioPin::Write to check for callbacks and post event.
- Update assembly declaration.

src/PAL/Include/CPU_GPIO_decl.h

@@ -129,6 +129,17 @@ GpioPinValue CPU_GPIO_GetPinState(GPIO_PIN Pin);
 //  Set state of output gpio pin
 void CPU_GPIO_SetPinState(GPIO_PIN Pin, GpioPinValue PinState);
 
+//
+// CPU_GPIO_TogglePinState
+//
+// Parameters :-
+//
+// pinNumber
+//   The number of the output pin for which the state is to be toggled.
+// Return Value
+//
+void CPU_GPIO_TogglePinState(GPIO_PIN pinNumber);
+
 //  Check if pin is already reserved
 //  Returns true if pin is already reserved
 bool CPU_GPIO_PinIsBusy(GPIO_PIN Pin);

src/System.Device.Gpio/sys_dev_gpio_native.cpp

@@ -102,7 +102,7 @@ const CLR_RT_NativeAssemblyData g_CLR_AssemblyNative_System_Device_Gpio =
     "System.Device.Gpio",
     0xB6D0ACC1,
     method_lookup,
-    { 100, 1, 0, 3 }
+    { 100, 1, 0, 4 }
 };
 
 // clang-format on

src/System.Device.Gpio/sys_dev_gpio_native.h

@@ -50,9 +50,8 @@ struct Library_sys_dev_gpio_native_System_Device_Gpio_GpioPin
     static const int FIELD___pinMode = 3;
     static const int FIELD___debounceTimeout = 4;
     static const int FIELD___callbacks = 5;
-    static const int FIELD___lastOutputValue = 6;
-    static const int FIELD___lastInputValue = 7;
-    static const int FIELD___disposedValue = 8;
+    static const int FIELD___lastInputValue = 6;
+    static const int FIELD___disposedValue = 7;
 
     NANOCLR_NATIVE_DECLARE(Read___SystemDeviceGpioPinValue);
     NANOCLR_NATIVE_DECLARE(Toggle___VOID);

src/System.Device.Gpio/sys_dev_gpio_native_System_Device_Gpio_GpioPin.cpp

@@ -55,16 +55,13 @@ HRESULT Library_sys_dev_gpio_native_System_Device_Gpio_GpioPin::Toggle___VOID(CL
         // sanity check for drive mode set to output so we don't mess up writing to an input pin
         if (driveMode >= GpioPinDriveMode_Output)
         {
-            // Not all lower level API offer a 'toggle', so need to rely on the last output value field and toggle that
-            // one
-            GpioPinValue newState =
-                (GpioPinValue)(GpioPinValue_High ^ (GpioPinValue)pThis[FIELD___lastOutputValue].NumericByRef().s4);
+            CPU_GPIO_TogglePinState(pinNumber);
 
-            // ...write back to the GPIO...
-            CPU_GPIO_SetPinState(pinNumber, newState);
-
-            // ... and finally store it
-            pThis[FIELD___lastOutputValue].NumericByRef().s4 = newState;
+            // fire event, only if there are callbacks registered
+            if (pThis[FIELD___callbacks].Dereference() != NULL)
+            {
+                PostManagedEvent(EVENT_GPIO, 0, (uint16_t)pinNumber, (uint32_t)CPU_GPIO_GetPinState(pinNumber));
+            }
         }
     }
     NANOCLR_NOCLEANUP();
@@ -282,8 +279,11 @@ HRESULT Library_sys_dev_gpio_native_System_Device_Gpio_GpioPin::Write(CLR_RT_Hea
     {
         CPU_GPIO_SetPinState(pinNumber, (GpioPinValue)pinValue);
 
-        // store the output value in the field
-        gpioPin[FIELD___lastOutputValue].NumericByRef().s4 = pinValue;
+        // fire event if there are callbacks registered
+        if (gpioPin[FIELD___callbacks].Dereference() != NULL)
+        {
+            PostManagedEvent(EVENT_GPIO, 0, (uint16_t)pinNumber, (uint32_t)pinValue);
+        }
     }
     else
     {

targets/CMSIS-OS/ChibiOS/nanoCLR/Windows.Devices.Gpio/cpu_gpio.cpp

@@ -244,6 +244,11 @@ void CPU_GPIO_SetPinState(GPIO_PIN pin, GpioPinValue PinState)
     palWriteLine(GetIoLine(pin), (int)PinState);
 }
 
+void CPU_GPIO_TogglePinState(GPIO_PIN pinNumber)
+{
+    palToggleLine(GetIoLine(pinNumber));
+}
+
 bool CPU_GPIO_EnableInputPin(
     GPIO_PIN pinNumber,
     CLR_UINT64 debounceTimeMilliseconds,

targets/FreeRTOS_ESP32/ESP32_WROOM_32/nanoCLR/Windows.Devices.Gpio/cpu_gpio.cpp

@@ -213,6 +213,15 @@ void CPU_GPIO_SetPinState(GPIO_PIN pin, GpioPinValue PinState)
     gpio_set_level((gpio_num_t)pin, (uint32_t)PinState);
 }
 
+// Toggle pin state
+void CPU_GPIO_TogglePinState(GPIO_PIN pinNumber)
+{
+    // platform DOES NOT support toggle
+    // need to do it "the hard way"
+    GpioPinValue newState = (GpioPinValue)(gpio_get_level((gpio_num_t)pinNumber) ^ GpioPinValue_High);
+    gpio_set_level((gpio_num_t)pinNumber, (uint32_t)newState);
+}
+
 // ISR called by IDF
 static void gpio_isr(void *arg)
 {