Use mp_int_t for setting pixelbuf slice indices

When handling negative steps, start and stop need to be mp_int_t so they
can be checked against a potential negative value during the for loop
used to set the slice values.

Author: dunkmann00

shared-bindings/_pixelbuf/PixelBuf.c

@@ -303,7 +303,7 @@ STATIC mp_obj_t pixelbuf_pixelbuf_subscr(mp_obj_t self_in, mp_obj_t index_in, mp
         size_t slice_len;
         if (slice.step > 0) {
             slice_len = slice.stop - slice.start;
-        }else{
+        } else {
             slice_len = 1 + slice.start - slice.stop;
         }
         if (slice.step > 1 || slice.step < -1) {

shared-bindings/_pixelbuf/PixelBuf.h

@@ -47,6 +47,6 @@ void common_hal__pixelbuf_pixelbuf_fill(mp_obj_t self, mp_obj_t item);
 void common_hal__pixelbuf_pixelbuf_show(mp_obj_t self);
 mp_obj_t common_hal__pixelbuf_pixelbuf_get_pixel(mp_obj_t self, size_t index);
 void common_hal__pixelbuf_pixelbuf_set_pixel(mp_obj_t self, size_t index, mp_obj_t item);
-void common_hal__pixelbuf_pixelbuf_set_pixels(mp_obj_t self_in, size_t start, size_t stop, mp_int_t step, mp_obj_t* values);
+void common_hal__pixelbuf_pixelbuf_set_pixels(mp_obj_t self_in, mp_int_t start, mp_int_t stop, mp_int_t step, mp_obj_t* values);
 
 #endif  // CP_SHARED_BINDINGS_PIXELBUF_PIXELBUF_H

shared-module/_pixelbuf/PixelBuf.c

@@ -216,16 +216,16 @@ void _pixelbuf_set_pixel(pixelbuf_pixelbuf_obj_t* self, size_t index, mp_obj_t v
     _pixelbuf_set_pixel_color(self, index, r, g, b, w);
 }
 
-void common_hal__pixelbuf_pixelbuf_set_pixels(mp_obj_t self_in, size_t start, size_t stop, mp_int_t step, mp_obj_t* values) {
+void common_hal__pixelbuf_pixelbuf_set_pixels(mp_obj_t self_in, mp_int_t start, mp_int_t stop, mp_int_t step, mp_obj_t* values) {
     pixelbuf_pixelbuf_obj_t* self = native_pixelbuf(self_in);
     size_t source_i = 0;
     if (step > 0) {
-        for (size_t target_i = start; target_i < stop; target_i += step) {
+        for (mp_int_t target_i = start; target_i < stop; target_i += step) {
             _pixelbuf_set_pixel(self, target_i, values[source_i]);
             source_i++;
         }
-    }else{
-        for (size_t target_i = start; target_i >= stop; target_i += step) {
+    } else {
+        for (mp_int_t target_i = start; target_i >= stop; target_i += step) {
             _pixelbuf_set_pixel(self, target_i, values[source_i]);
             source_i++;
         }