From 830e52fa67803d3d4506948d4c8888e1e8eea586 Mon Sep 17 00:00:00 2001
From: Vicki Pfau <vi@endrift.com>
Date: Sun, 17 Feb 2019 22:13:40 -0800
Subject: [PATCH] GBA SIO: Prevent writing read-only multiplayer bits

---
 CHANGES       | 1 +
 src/gba/sio.c | 1 +
 2 files changed, 2 insertions(+)

diff --git a/CHANGES b/CHANGES
index 8aa727d57..62ca075d1 100644
--- a/CHANGES
+++ b/CHANGES
@@ -7,6 +7,7 @@ Bugfixes:
  - GB Serialize: Fix loading states with negative pixel x (fixes mgba.io/i/1293)
  - Qt: Fix audio context holding onto closed game controller
  - Switch: Fix gyroscope orientation (fixes mgba.io/i/1300)
+ - GBA SIO: Prevent writing read-only multiplayer bits
 Misc:
  - GBA Video: Improve sprite cycle counting (fixes mgba.io/i/1274)
 
diff --git a/src/gba/sio.c b/src/gba/sio.c
index d620be5a7..800af8aea 100644
--- a/src/gba/sio.c
+++ b/src/gba/sio.c
@@ -164,6 +164,7 @@ void GBASIOWriteSIOCNT(struct GBASIO* sio, uint16_t value) {
 			}
 			break;
 		case SIO_MULTI:
+			value &= 0xFF83;
 			value |= 0xC;
 			break;
 		default: