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mGBA Game Boy Advance Emulator

GB: Downgrade DMG-only ROMs from CGB mode even without boot ROM
Vicki Pfau vi@endrift.com
Fri, 20 Nov 2020 00:35:52 -0800
commit

2c9dd238cc3520af8af8584d366e89ed00f9fea4

parent

ce00cf77274f5f83d9f2156e417a0fe145acaaa9

2 files changed, 6 insertions(+), 0 deletions(-)

jump to
M CHANGES → CHANGES 
@@ -1,6 +1,7 @@
 0.8.5: (Future)
 Emulation fixes:
  - ARM: Fix Addressing mode 1 shifter on rs == pc (fixes mgba.io/i/1926)
+ - GB: Downgrade DMG-only ROMs from CGB mode even without boot ROM
  - GBA Memory: Mark Famicom Mini games 22 through 28 as non-mirroring
 Other fixes:
  - CMake: Fix build with downstream minizip that exports incompatible symbols
M src/gb/gb.c → src/gb/gb.c 
@@ -481,6 +481,11 @@ struct SM83Core* cpu = gb->cpu;
 	const struct GBCartridge* cart = (const struct GBCartridge*) &gb->memory.rom[0x100];
 	int nextDiv = 0;
 
+	if (gb->model >= GB_MODEL_CGB && !(cart->cgb & 0x80)) {
+		gb->model = GB_MODEL_DMG;
+		GBVideoDisableCGB(&gb->video);
+	}
+
 	switch (gb->model) {
 	case GB_MODEL_AUTODETECT: // Silence warnings
 		gb->model = GB_MODEL_DMG;