M CHANGES → CHANGES

@@ -27,6 +27,7 @@ - GBA Video: Fix enabling layers in non-tile modes (fixes mgba.io/i/1317)
  - Qt: Fix quick load recent accidentally saving (fixes mgba.io/i/1309)
  - GBA: Fix video timing when skipping BIOS (fixes mgba.io/i/1318)
  - 3DS: Work around menu freezing (fixes mgba.io/i/1294)
+ - GBA DMA: Fix invalid DMA handling (fixes mgba.io/i/1301)
 Misc:
  - GBA Savedata: EEPROM performance fixes
  - GBA Savedata: Automatically map 1Mbit Flash files as 1Mbit Flash

M src/gba/dma.c → src/gba/dma.c

@@ -260,15 +260,13 @@ memory->dmaTransferRegister = cpu->memory.load32(cpu, source, 0);
 		}
 		gba->bus = memory->dmaTransferRegister;
 		cpu->memory.store32(cpu, dest, memory->dmaTransferRegister, 0);
-		memory->dmaTransferRegister &= 0xFFFF0000;
-		memory->dmaTransferRegister |= memory->dmaTransferRegister >> 16;
 	} else {
 		if (sourceRegion == REGION_CART2_EX && (memory->savedata.type == SAVEDATA_EEPROM || memory->savedata.type == SAVEDATA_EEPROM512)) {
 			memory->dmaTransferRegister = GBASavedataReadEEPROM(&memory->savedata);
-		} else {
-			if (source) {
-				memory->dmaTransferRegister = cpu->memory.load16(cpu, source, 0);
-			}
+			memory->dmaTransferRegister |= memory->dmaTransferRegister << 16;
+		} else if (source) {
+			memory->dmaTransferRegister = cpu->memory.load16(cpu, source, 0);
+			memory->dmaTransferRegister |= memory->dmaTransferRegister << 16;
 		}
 		if (destRegion == REGION_CART2_EX) {
 			if (memory->savedata.type == SAVEDATA_AUTODETECT) {
@@ -282,7 +280,6 @@ } else {
 			cpu->memory.store16(cpu, dest, memory->dmaTransferRegister, 0);
 
 		}
-		memory->dmaTransferRegister |= memory->dmaTransferRegister << 16;
 		gba->bus = memory->dmaTransferRegister;
 	}
 	int sourceOffset = DMA_OFFSET[GBADMARegisterGetSrcControl(info->reg)] * width;