Small hook rework

Two things are done here: loop() hooks are introduced, and both loop and
event handler hooks are pre-allocated for HOOK_MAX (64 by default)
elements.

Two helpers are introduced too, that make it easier to append a new hook
to the end of these arrays.

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>

KeyboardioFirmware.cpp

@@ -16,8 +16,15 @@ Keyboardio_::setup(void) {
     temporary_keymap = primary_keymap = Storage.load_primary_keymap(KEYMAPS);
 }
 
+custom_loop_t loopHooks[HOOK_MAX] = {NULL};
+
 void
 Keyboardio_::loop(void) {
+    for (byte i = 0; loopHooks[i] != NULL && i < HOOK_MAX; i++) {
+        custom_loop_t hook = loopHooks[i];
+        (*hook)();
+    }
+
     KeyboardHardware.scan_matrix();
     LEDControl.update(temporary_keymap);
     Keyboard.sendReport();

hooks.cpp

@@ -0,0 +1,27 @@
+#include "hooks.h"
+
+void
+event_handler_hook_add (custom_handler_t hook) {
+    byte i;
+
+    for (i = 0; i < HOOK_MAX && eventHandlers[i] != NULL; i++) {
+    }
+
+    if (i == HOOK_MAX)
+        return;
+
+    eventHandlers[i] = hook;
+}
+
+void
+loop_hook_add (custom_loop_t hook) {
+    byte i;
+
+    for (i = 0; i < HOOK_MAX && loopHooks[i] != NULL; i++) {
+    }
+
+    if (i == HOOK_MAX)
+        return;
+
+    loopHooks[i] = hook;
+}

hooks.h

@@ -0,0 +1,15 @@
+#pragma once
+
+#include <Arduino.h>
+
+#define HOOK_MAX 64
+
+typedef bool (*custom_handler_t)(byte row, byte col, uint8_t currentState, uint8_t previousState);
+extern custom_handler_t eventHandlers[HOOK_MAX];
+
+void event_handler_hook_add (custom_handler_t hook);
+
+typedef void (*custom_loop_t)(void);
+extern custom_loop_t loopHooks[HOOK_MAX];
+
+void loop_hook_add (custom_loop_t hook);

key_events.cpp

@@ -41,8 +41,7 @@ void handle_synthetic_key_event(Key mappedKey, uint8_t currentState, uint8_t pre
     }
 }
 
-__attribute__((weak))
-custom_handler_t eventHandlers[] = {
+custom_handler_t eventHandlers[HOOK_MAX] = {
     handle_key_event_default,
     (custom_handler_t) NULL
 };
@@ -56,7 +55,7 @@ Key lookup_key(byte keymap, byte row, byte col) {
 }
 
 void handle_key_event(byte row, byte col, uint8_t currentState, uint8_t previousState) {
-    for (byte i = 0; eventHandlers[i] != NULL; i++) {
+    for (byte i = 0; eventHandlers[i] != NULL && i < HOOK_MAX; i++) {
         custom_handler_t handler = eventHandlers[i];
         if ((*handler)(row, col, currentState, previousState))
             return;

key_events.h

@@ -8,14 +8,12 @@
 #include "Storage.h"
 #include "keymap_metadata.h"
 #include "generated/keymaps.h"
+#include "hooks.h"
 
 //static const Key keymaps[KEYMAPS][ROWS][COLS];
 extern uint8_t primary_keymap;
 extern uint8_t temporary_keymap;
 
-typedef bool (*custom_handler_t)(byte row, byte col, uint8_t currentState, uint8_t previousState);
-extern custom_handler_t eventHandlers[];
-
 // sending events to the computer
 void handle_synthetic_key_event( Key mappedKey, uint8_t currentState, uint8_t previousState);
 void handle_key_event(byte row, byte col, uint8_t currentState, uint8_t previousState);