From 9b6b7c73929b8be963d0d453f3a41a60eb87bef0 Mon Sep 17 00:00:00 2001
From: Vicki Pfau <vi@endrift.com>
Date: Sat, 15 Jan 2022 20:32:50 -0800
Subject: [PATCH] GBA DMA: Fix DMA source direction bits being cleared (fixes
 #2410)

---
 CHANGES       |  1 +
 src/gba/dma.c | 11 +++++++----
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/CHANGES b/CHANGES
index 74f434bb2..8a20eda57 100644
--- a/CHANGES
+++ b/CHANGES
@@ -17,6 +17,7 @@ Emulation fixes:
  - GB Video: Draw SGB border pieces that overlap GB graphics (fixes mgba.io/i/1339)
  - GBA: Improve timing when not booting from BIOS
  - GBA BIOS: Work around IRQ handling hiccup in Mario & Luigi (fixes mgba.io/i/1059)
+ - GBA DMA: Fix DMA source direction bits being cleared (fixes mgba.io/i/2410)
  - GBA I/O: Redo internal key input, enabling edge-based key IRQs
  - GBA I/O: Disable open bus behavior on invalid register 06A
  - GBA Memory: Fix misaligned 32-bit I/O loads (fixes mgba.io/i/2307)
diff --git a/src/gba/dma.c b/src/gba/dma.c
index d30f0291a..5807e506f 100644
--- a/src/gba/dma.c
+++ b/src/gba/dma.c
@@ -83,9 +83,6 @@ uint16_t GBADMAWriteCNT_HI(struct GBA* gba, int dma, uint16_t control) {
 
 	if (!wasEnabled && GBADMARegisterIsEnable(currentDma->reg)) {
 		currentDma->nextSource = currentDma->source;
-		if (currentDma->nextSource >= BASE_CART0 && currentDma->nextSource < BASE_CART_SRAM && GBADMARegisterGetSrcControl(currentDma->reg) < 3) {
-			currentDma->reg = GBADMARegisterClearSrcControl(currentDma->reg);
-		}
 		currentDma->nextDest = currentDma->dest;
 
 		uint32_t width = 2 << GBADMARegisterGetWidth(currentDma->reg);
@@ -291,7 +288,13 @@ void GBADMAService(struct GBA* gba, int number, struct GBADMA* info) {
 		}
 		gba->bus = memory->dmaTransferRegister;
 	}
-	int sourceOffset = DMA_OFFSET[GBADMARegisterGetSrcControl(info->reg)] * width;
+
+	int sourceOffset;
+	if (info->nextSource >= BASE_CART0 && info->nextSource < BASE_CART_SRAM && GBADMARegisterGetSrcControl(info->reg) < 3) {
+		sourceOffset = width;
+	} else {
+		sourceOffset = DMA_OFFSET[GBADMARegisterGetSrcControl(info->reg)] * width;
+	}
 	int destOffset = DMA_OFFSET[GBADMARegisterGetDestControl(info->reg)] * width;
 	if (source) {
 		source += sourceOffset;