displayio: implement, use allocate_display_or_raise

2 files changed, 21 insertions, 0 deletions

diff --git a/shared-module/displayio/__init__.c b/shared-module/displayio/__init__.c
index efa61265e..fd58a0322 100644
--- a/shared-module/displayio/__init__.c
+++ b/shared-module/displayio/__init__.c
@@ -308,3 +308,21 @@ void displayio_area_transform_within(bool mirror_x, bool mirror_y, bool transpos
         transformed->x1 = whole->x1 + (y1 - whole->y1);
     }
 }
+
+primary_display_t *allocate_display() {
+    for (uint8_t i = 0; i < CIRCUITPY_DISPLAY_LIMIT; i++) {
+        mp_const_obj_t display_type = displays[i].display.base.type;
+        if (display_type == NULL || display_type == &mp_type_NoneType) {
+            return &displays[i];
+        }
+    }
+    return NULL;
+
+primary_display_t *allocate_display_or_raise() {
+    primary_display_t *result = allocate_display();
+    if (!result) {
+        mp_raise_RuntimeError(translate("Too many displays"));
+    }
+}
+
+}
diff --git a/shared-module/displayio/__init__.h b/shared-module/displayio/__init__.h
index e78bc61ce..4e1297c8d 100644
--- a/shared-module/displayio/__init__.h
+++ b/shared-module/displayio/__init__.h
@@ -54,4 +54,7 @@ void displayio_background(void);
 void reset_displays(void);
 void displayio_gc_collect(void);
 
+primary_display_t *allocate_display(void);
+primary_display_t *allocate_display_or_raise(void);
+
 #endif // MICROPY_INCLUDED_SHARED_MODULE_DISPLAYIO___INIT___H