fix(keymap): Fix overflow in get/set bindings (zmkfirmware#3205)

With the binding referenced to as uint8_t the keymap would be incorrect if more than 256 positions were in use, going to a uint16_t gives large enough headroom to not have to worry

Author: ReFil

app/include/zmk/keymap.h

@@ -42,8 +42,8 @@ int zmk_keymap_layer_to(zmk_keymap_layer_id_t layer);
 const char *zmk_keymap_layer_name(zmk_keymap_layer_id_t layer);
 
 const struct zmk_behavior_binding *zmk_keymap_get_layer_binding_at_idx(zmk_keymap_layer_id_t layer,
-                                                                       uint8_t binding_idx);
-int zmk_keymap_set_layer_binding_at_idx(zmk_keymap_layer_id_t layer, uint8_t binding_idx,
+                                                                       uint16_t binding_idx);
+int zmk_keymap_set_layer_binding_at_idx(zmk_keymap_layer_id_t layer, uint16_t binding_idx,
                                         const struct zmk_behavior_binding binding);
 
 #if IS_ENABLED(CONFIG_ZMK_KEYMAP_LAYER_REORDERING)

app/src/keymap.c

@@ -224,7 +224,7 @@ const char *zmk_keymap_layer_name(zmk_keymap_layer_id_t layer_id) {
 }
 
 const struct zmk_behavior_binding *
-zmk_keymap_get_layer_binding_at_idx(zmk_keymap_layer_id_t layer_id, uint8_t binding_idx) {
+zmk_keymap_get_layer_binding_at_idx(zmk_keymap_layer_id_t layer_id, uint16_t binding_idx) {
     if (binding_idx >= ZMK_KEYMAP_LEN) {
         return NULL;
     }
@@ -259,7 +259,7 @@ zmk_keymap_get_layer_binding_at_idx(zmk_keymap_layer_id_t layer_id, uint8_t bind
 
 static uint8_t zmk_keymap_layer_pending_changes[ZMK_KEYMAP_LAYERS_LEN][PENDING_ARRAY_SIZE];
 
-int zmk_keymap_set_layer_binding_at_idx(zmk_keymap_layer_id_t layer_id, uint8_t binding_idx,
+int zmk_keymap_set_layer_binding_at_idx(zmk_keymap_layer_id_t layer_id, uint16_t binding_idx,
                                         struct zmk_behavior_binding binding) {
     if (binding_idx >= ZMK_KEYMAP_LEN) {
         return -EINVAL;
@@ -304,7 +304,7 @@ int zmk_keymap_set_layer_binding_at_idx(zmk_keymap_layer_id_t layer_id, uint8_t
 
 #else
 
-int zmk_keymap_set_layer_binding_at_idx(zmk_keymap_layer_id_t layer_id, uint8_t binding_idx,
+int zmk_keymap_set_layer_binding_at_idx(zmk_keymap_layer_id_t layer_id, uint16_t binding_idx,
                                         struct zmk_behavior_binding binding) {
     return -ENOTSUP;
 }