From 91515b6b1077e863ea9265022340cd9ff4874bcf Mon Sep 17 00:00:00 2001
From: Michel Heily <michelheily@gmail.com>
Date: Sat, 23 May 2020 01:55:40 +0300
Subject: [PATCH] core/gpu: Ignore top bit when reading colors from the palette

According to CowBite, the top bit is supposed to be ignored.

fixes #99


Former-commit-id: 28a43311726f9ce5ef26c77687fedecc33b286e0
Former-commit-id: df0b025ed6d51e36bcffd4c91250858167b42f40
---
 rustboyadvance-core/src/gpu/mod.rs | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/rustboyadvance-core/src/gpu/mod.rs b/rustboyadvance-core/src/gpu/mod.rs
index 7854893..1302560 100644
--- a/rustboyadvance-core/src/gpu/mod.rs
+++ b/rustboyadvance-core/src/gpu/mod.rs
@@ -340,14 +340,14 @@ impl Gpu {
     }
 
     #[inline(always)]
-    pub fn get_palette_color(&self, index: u32, palette_index: u32, offset: u32) -> Rgb15 {
-        if index == 0 || (palette_index != 0 && index % 16 == 0) {
+    pub fn get_palette_color(&self, index: u32, palette_bank: u32, offset: u32) -> Rgb15 {
+        if index == 0 || (palette_bank != 0 && index % 16 == 0) {
             return Rgb15::TRANSPARENT;
         }
-        Rgb15(
-            self.palette_ram
-                .read_16(offset + 2 * index + 0x20 * palette_index),
-        )
+        let value = self.palette_ram.read_16(offset + 2 * index + 0x20 * palette_bank);
+
+        // top bit is ignored
+        Rgb15(value & 0x7FFF)
     }
 
     #[inline]