From a694a23736ee228f7ddf6c13f43fef86ee5a8961 Mon Sep 17 00:00:00 2001
From: Nathaniel Walizer <robots.are.love@gmail.com>
Date: Thu, 9 Jan 2025 02:02:37 -0800
Subject: [PATCH] Fix MMC3 bank mirroring

---
 src/map/mmc3.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/map/mmc3.c b/src/map/mmc3.c
index 513dd2e..329e098 100644
--- a/src/map/mmc3.c
+++ b/src/map/mmc3.c
@@ -38,7 +38,7 @@ typedef struct {
 } mmc3_mapper;
 
 static inline uint8_t* mmc3_prg_bank(mmc3_mapper* map, int bank) {
-    return &map->prg_rom[bank << 13];
+    return &map->prg_rom[(bank % map->prg_rom_banks) << 13];
 }
 
 static inline void mmc3_map_prg(mmc3_mapper* map,
@@ -61,7 +61,7 @@ static inline void mmc3_update_prg(mmc3_mapper* map,
 }
 
 static inline uint8_t* mmc3_chr_bank(mmc3_mapper* map, int bank) {
-    return &map->chr_rom[bank << 10];
+    return &map->chr_rom[(bank % map->chr_rom_banks) << 10];
 }
 
 static inline void mmc3_map_2k_chr(mmc3_mapper* map,