set_eic_channel_handler.diff

diff --git a/samd/external_interrupts.c b/samd/external_interrupts.c
index 384ff99..42e315d 100644
--- a/samd/external_interrupts.c
+++ b/samd/external_interrupts.c
@@ -36,6 +36,7 @@
 // has one user.
 static void *channel_data[EIC_EXTINT_NUM];
 static uint8_t channel_handler[EIC_EXTINT_NUM];
+static channel_handler_t *channel_handler_func[EIC_EXTINT_NUM];
 
 void external_interrupt_handler(uint8_t channel) {
     uint8_t handler = channel_handler[channel];
@@ -43,6 +44,11 @@ void external_interrupt_handler(uint8_t channel) {
         pulsein_interrupt_handler(channel);
     } else if (handler == EIC_HANDLER_INCREMENTAL_ENCODER) {
         incrementalencoder_interrupt_handler(channel);
+    } else if (handler == EIC_HANDLER_FUNC) {
+        channel_handler_t *func = channel_handler_func[channel];
+        if (func != NULL) {
+            func(channel);
+        }
     }
     EIC->INTFLAG.reg = (1 << channel) << EIC_INTFLAG_EXTINT_Pos;
 }
@@ -96,6 +102,10 @@ void turn_off_eic_channel(uint8_t eic_channel) {
     }
 }
 
+void set_eic_channel_handler(uint8_t eic_channel, channel_handler_t *handler) {
+    channel_handler_func[eic_channel] = handler;
+}
+
 void* get_eic_channel_data(uint8_t eic_channel) {
     return channel_data[eic_channel];
 }
diff --git a/samd/external_interrupts.h b/samd/external_interrupts.h
index 12d8206..86eb0a4 100644
--- a/samd/external_interrupts.h
+++ b/samd/external_interrupts.h
@@ -33,6 +33,9 @@
 #define EIC_HANDLER_NO_INTERRUPT 0x0
 #define EIC_HANDLER_PULSEIN 0x1
 #define EIC_HANDLER_INCREMENTAL_ENCODER 0x2
+#define EIC_HANDLER_FUNC 0x3
+
+typedef void channel_handler_t(uint8_t);
 
 void turn_on_external_interrupt_controller(void);
 void turn_off_external_interrupt_controller(void);
@@ -46,6 +49,8 @@ bool eic_get_enable(void);
 void eic_set_enable(bool value);
 void eic_reset(void);
 
+void set_eic_channel_handler(uint8_t eic_channel, channel_handler_t *handler);
+
 void* get_eic_channel_data(uint8_t eic_channel);
 void set_eic_channel_data(uint8_t eic_channel, void* data);