all repos — mgba @ 7df5b67a71d4406d1261510ae6296e879db33c39

mGBA Game Boy Advance Emulator

GBA DMA: Only update DMA scheduling if needed
Vicki Pfau vi@endrift.com
Fri, 21 Aug 2020 02:41:03 -0700
commit

7df5b67a71d4406d1261510ae6296e879db33c39

parent

5c58186f03fb053038ee804b44051f21623ec62c

1 files changed, 10 insertions(+), 2 deletions(-)

jump to
M src/gba/dma.c → src/gba/dma.c 
@@ -134,29 +134,37 @@
 void GBADMARunHblank(struct GBA* gba, int32_t cycles) {
 	struct GBAMemory* memory = &gba->memory;
 	struct GBADMA* dma;
+	bool found = false;
 	int i;
 	for (i = 0; i < 4; ++i) {
 		dma = &memory->dma[i];
 		if (GBADMARegisterIsEnable(dma->reg) && GBADMARegisterGetTiming(dma->reg) == GBA_DMA_TIMING_HBLANK && !dma->nextCount) {
 			dma->when = mTimingCurrentTime(&gba->timing) + 3 + cycles;
 			dma->nextCount = dma->count;
+			found = true;
 		}
 	}
-	GBADMAUpdate(gba);
+	if (found) {
+		GBADMAUpdate(gba);
+	}
 }
 
 void GBADMARunVblank(struct GBA* gba, int32_t cycles) {
 	struct GBAMemory* memory = &gba->memory;
 	struct GBADMA* dma;
+	bool found = false;
 	int i;
 	for (i = 0; i < 4; ++i) {
 		dma = &memory->dma[i];
 		if (GBADMARegisterIsEnable(dma->reg) && GBADMARegisterGetTiming(dma->reg) == GBA_DMA_TIMING_VBLANK && !dma->nextCount) {
 			dma->when = mTimingCurrentTime(&gba->timing) + 3 + cycles;
 			dma->nextCount = dma->count;
+			found = true;
 		}
 	}
-	GBADMAUpdate(gba);
+	if (found) {
+		GBADMAUpdate(gba);
+	}
 }
 
 void GBADMARunDisplayStart(struct GBA* gba, int32_t cycles) {