From c3b81a45850440294268e6d36347e6723b9dedd6 Mon Sep 17 00:00:00 2001
From: Corwin Kuiper <corwin@kuiper.dev>
Date: Sun, 30 May 2021 12:47:00 +0100
Subject: [PATCH] don't touch highest 16 bits

---
 agb/src/display/object.rs | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/agb/src/display/object.rs b/agb/src/display/object.rs
index 5c717138..d7883191 100644
--- a/agb/src/display/object.rs
+++ b/agb/src/display/object.rs
@@ -52,7 +52,10 @@ pub struct ObjectAttribute {
 impl ObjectAttribute {
     unsafe fn commit(&self, index: usize) {
         OBJECT_MEMORY_STANDARD.set(index * 2, self.low);
-        OBJECT_MEMORY_STANDARD.set(index * 2 + 1, self.high);
+        // preserve top set of bits
+        let high_bits = OBJECT_MEMORY_STANDARD.get(index * 2 + 1);
+        let new_high_bits = (high_bits & !((1 << 16) - 1)) | self.high;
+        OBJECT_MEMORY_STANDARD.set(index * 2 + 1, new_high_bits);
     }
 
     pub fn set_hflip(&mut self, hflip: bool) {