Add attach/detachInterrupt support

Fixes #21

cores/rp2040/Arduino.h

@@ -28,6 +28,7 @@
 #include "api/ArduinoAPI.h"
 
 #include <pins_arduino.h>
+#define digitalPinToInterrupt(P) (P)
 
 #include "debug_internal.h"
 
@@ -35,6 +36,13 @@
 extern "C"{
 #endif // __cplusplus
 
+void interrupts();
+void noInterrupts();
+void attachInterrupt(pin_size_t pin, voidFuncPtr callback, PinStatus mode);
+void detachInterrupt(pin_size_t pin);
+
+
+
 void pinMode(pin_size_t pinNumber, PinMode pinMode);
 
 // SIO (GPIO)

cores/rp2040/wiring_private.cpp

@@ -19,6 +19,7 @@
  */
 
 #include <Arduino.h>
+#include <hardware/gpio.h>
 #include <hardware/sync.h>
 #include <stack>
 
@@ -37,3 +38,30 @@ extern "C" void noInterrupts() {
     irqStack.push(save_and_disable_interrupts());
 }
 
+static uint32_t _irqMap = 0;
+
+extern "C" void attachInterrupt(pin_size_t pin, voidFuncPtr callback, PinStatus mode) {
+    uint32_t events;
+    switch (mode) {
+        case LOW:     events = 1; break;
+        case HIGH:    events = 2; break;
+        case FALLING: events = 4; break;
+        case RISING:  events = 8; break;
+        case CHANGE:  events = 4 | 8; break;
+        default:      return;  // ERROR
+    }
+    noInterrupts();
+    detachInterrupt(pin);
+    gpio_set_irq_enabled_with_callback(pin, events, true, (gpio_irq_callback_t)callback);
+    _irqMap |= 1<<pin;
+    interrupts();
+}
+
+extern "C" void detachInterrupt(pin_size_t pin){
+    noInterrupts();
+    if (_irqMap & (1<<pin)) {
+        gpio_set_irq_enabled(pin, 0x0f /* all */, false);
+        _irqMap &= ~(1<<pin);
+    }
+    interrupts();
+}