From b1f991bf9431c99e2ba3b2486d4d38b3d74d77b3 Mon Sep 17 00:00:00 2001
From: Vicki Pfau <vi@endrift.com>
Date: Tue, 9 May 2023 14:50:57 -0700
Subject: [PATCH] GB I/O: Read back proper SVBK value after writing 0 (fixes
 #2921)

---
 CHANGES     | 1 +
 src/gb/io.c | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/CHANGES b/CHANGES
index ca460464c..d45c14d5e 100644
--- a/CHANGES
+++ b/CHANGES
@@ -6,6 +6,7 @@ Features:
  - Debugger: Add range watchpoints
 Emulation fixes:
  - GB Audio: Fix channels 1/2 staying muted if restarted after long silence
+ - GB I/O: Read back proper SVBK value after writing 0 (fixes mgba.io/i/2921)
  - GB Serialize: Add missing Pocket Cam state to savestates
  - GB SIO: Disabling SIO should cancel pending transfers (fixes mgba.io/i/2537)
  - GB Video: Implement DMG-style sprite ordering
diff --git a/src/gb/io.c b/src/gb/io.c
index ba4473550..560ad7e62 100644
--- a/src/gb/io.c
+++ b/src/gb/io.c
@@ -491,7 +491,7 @@ void GBIOWrite(struct GB* gb, unsigned address, uint8_t value) {
 				return;
 			case GB_REG_SVBK:
 				GBMemorySwitchWramBank(&gb->memory, value);
-				value = gb->memory.wramCurrentBank;
+				value &= 7;
 				break;
 			default:
 				goto failed;