From 8cba145c90294a001ec5814fb501a7b96a055780 Mon Sep 17 00:00:00 2001
From: Jeff Epler <jepler@gmail.com>
Date: Mon, 30 Mar 2020 10:47:14 -0500
Subject: [PATCH] displayio: implement, use allocate_new_display_bus_or_raise

---
 shared-bindings/displayio/FourWire.c    | 13 +------------
 shared-bindings/displayio/I2CDisplay.c  | 13 +------------
 shared-bindings/displayio/ParallelBus.c | 13 +------------
 shared-module/displayio/__init__.c      | 17 +++++++++++++++++
 shared-module/displayio/__init__.h      |  2 ++
 5 files changed, 22 insertions(+), 36 deletions(-)

diff --git a/shared-bindings/displayio/FourWire.c b/shared-bindings/displayio/FourWire.c
index 77329578a4..1cd51b2e2d 100644
--- a/shared-bindings/displayio/FourWire.c
+++ b/shared-bindings/displayio/FourWire.c
@@ -82,19 +82,8 @@ STATIC mp_obj_t displayio_fourwire_make_new(const mp_obj_type_t *type, size_t n_
     mcu_pin_obj_t *chip_select = validate_obj_is_free_pin(args[ARG_chip_select].u_obj);
     mcu_pin_obj_t *reset = validate_obj_is_free_pin_or_none(args[ARG_reset].u_obj);
 
-    displayio_fourwire_obj_t* self = NULL;
     mp_obj_t spi = args[ARG_spi_bus].u_obj;
-    for (uint8_t i = 0; i < CIRCUITPY_DISPLAY_LIMIT; i++) {
-        if (displays[i].fourwire_bus.base.type == NULL ||
-            displays[i].fourwire_bus.base.type == &mp_type_NoneType) {
-            self = &displays[i].fourwire_bus;
-            self->base.type = &displayio_fourwire_type;
-            break;
-        }
-    }
-    if (self == NULL) {
-        mp_raise_RuntimeError(translate("Too many display busses"));
-    }
+    displayio_fourwire_obj_t* self = &allocate_display_bus_or_raise()->fourwire_bus;
 
     uint8_t polarity = args[ARG_polarity].u_int;
     if (polarity != 0 && polarity != 1) {
diff --git a/shared-bindings/displayio/I2CDisplay.c b/shared-bindings/displayio/I2CDisplay.c
index 2e312aa14e..dd3333f6de 100644
--- a/shared-bindings/displayio/I2CDisplay.c
+++ b/shared-bindings/displayio/I2CDisplay.c
@@ -71,19 +71,8 @@ STATIC mp_obj_t displayio_i2cdisplay_make_new(const mp_obj_type_t *type, size_t
 
     mcu_pin_obj_t *reset = validate_obj_is_free_pin_or_none(args[ARG_reset].u_obj);
 
-    displayio_i2cdisplay_obj_t* self = NULL;
     mp_obj_t i2c = args[ARG_i2c_bus].u_obj;
-    for (uint8_t i = 0; i < CIRCUITPY_DISPLAY_LIMIT; i++) {
-        if (displays[i].i2cdisplay_bus.base.type == NULL ||
-            displays[i].i2cdisplay_bus.base.type == &mp_type_NoneType) {
-            self = &displays[i].i2cdisplay_bus;
-            self->base.type = &displayio_i2cdisplay_type;
-            break;
-        }
-    }
-    if (self == NULL) {
-        mp_raise_RuntimeError(translate("Too many display busses"));
-    }
+    displayio_i2cdisplay_obj_t* self = &allocate_display_bus_or_raise()->i2cdisplay_bus;
 
     common_hal_displayio_i2cdisplay_construct(self,
         MP_OBJ_TO_PTR(i2c), args[ARG_device_address].u_int, reset);
diff --git a/shared-bindings/displayio/ParallelBus.c b/shared-bindings/displayio/ParallelBus.c
index b3a876f903..4d9ffb0a1e 100644
--- a/shared-bindings/displayio/ParallelBus.c
+++ b/shared-bindings/displayio/ParallelBus.c
@@ -83,18 +83,7 @@ STATIC mp_obj_t displayio_parallelbus_make_new(const mp_obj_type_t *type, size_t
     mcu_pin_obj_t *read = validate_obj_is_free_pin(args[ARG_read].u_obj);
     mcu_pin_obj_t *reset = validate_obj_is_free_pin(args[ARG_reset].u_obj);
 
-    displayio_parallelbus_obj_t* self = NULL;
-    for (uint8_t i = 0; i < CIRCUITPY_DISPLAY_LIMIT; i++) {
-        if (displays[i].parallel_bus.base.type== NULL ||
-            displays[i].parallel_bus.base.type == &mp_type_NoneType) {
-            self = &displays[i].parallel_bus;
-            self->base.type = &displayio_parallelbus_type;
-            break;
-        }
-    }
-    if (self == NULL) {
-        mp_raise_RuntimeError(translate("Too many display busses"));
-    }
+    displayio_parallelbus_obj_t* self = &allocate_display_bus_or_raise()->parallel_bus;
 
     common_hal_displayio_parallelbus_construct(self, data0, command, chip_select, write, read, reset);
     return self;
diff --git a/shared-module/displayio/__init__.c b/shared-module/displayio/__init__.c
index fd58a0322a..4844dfe60b 100644
--- a/shared-module/displayio/__init__.c
+++ b/shared-module/displayio/__init__.c
@@ -326,3 +326,20 @@ primary_display_t *allocate_display_or_raise() {
 }
 
 }
+primary_display_t *allocate_display_bus(void) {
+    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_bus_or_raise(void) {
+    primary_display_t *result = allocate_display_bus();
+    if (result) {
+        return result;
+    }
+    mp_raise_RuntimeError(translate("Too many display busses"));
+}
diff --git a/shared-module/displayio/__init__.h b/shared-module/displayio/__init__.h
index 4e1297c8d1..638c2091e0 100644
--- a/shared-module/displayio/__init__.h
+++ b/shared-module/displayio/__init__.h
@@ -56,5 +56,7 @@ void displayio_gc_collect(void);
 
 primary_display_t *allocate_display(void);
 primary_display_t *allocate_display_or_raise(void);
+primary_display_t *allocate_display_bus(void);
+primary_display_t *allocate_display_bus_or_raise(void);
 
 #endif // MICROPY_INCLUDED_SHARED_MODULE_DISPLAYIO___INIT___H