M include/mgba/internal/ds/renderers/software.h → include/mgba/internal/ds/renderers/software.h

@@ -21,6 +21,7 @@ struct GBAVideoSoftwareRenderer engB;
 
 	DSRegisterDISPCNT dispcntA;
 	DSRegisterDISPCNT dispcntB;
+	DSRegisterPOWCNT1 powcnt;
 
 	color_t* outputBuffer;
 	int outputBufferStride;

M include/mgba/internal/ds/video.h → include/mgba/internal/ds/video.h

@@ -58,6 +58,10 @@ DECL_BITS(DSRegisterDISPCNT, CharBase, 24, 3);
 DECL_BITS(DSRegisterDISPCNT, ScreenBase, 27, 3);
 // TODO
 
+DECL_BITFIELD(DSRegisterPOWCNT1, uint16_t);
+// TODO
+DECL_BIT(DSRegisterPOWCNT1, Swap, 15);
+
 struct DSVideoRenderer {
 	void (*init)(struct DSVideoRenderer* renderer);
 	void (*reset)(struct DSVideoRenderer* renderer);

M src/ds/io.c → src/ds/io.c

@@ -440,6 +440,11 @@ case DS9_REG_SQRT_PARAM_3:
 			ds->memory.io9[DS9_REG_SQRTCNT >> 1] = _scheduleSqrt(ds, ds->memory.io9[DS9_REG_SQRTCNT >> 1]);
 			break;
 
+		// High Video
+		case DS9_REG_POWCNT1:
+			value = ds->video.renderer->writeVideoRegister(ds->video.renderer, address, value);
+			break;
+
 		default:
 			{
 				uint32_t v2 = DSIOWrite(&ds->ds9, address, value);

M src/ds/renderers/software.c → src/ds/renderers/software.c

@@ -42,9 +42,11 @@ struct DSVideoSoftwareRenderer* softwareRenderer = (struct DSVideoSoftwareRenderer*) renderer;
 	softwareRenderer->engA.d.palette = &renderer->palette[0];
 	softwareRenderer->engA.d.oam = &renderer->oam->oam[0];
 	softwareRenderer->engA.masterEnd = DS_VIDEO_HORIZONTAL_PIXELS;
+	softwareRenderer->engA.outputBufferStride = softwareRenderer->outputBufferStride;
 	softwareRenderer->engB.d.palette = &renderer->palette[512];
 	softwareRenderer->engB.d.oam = &renderer->oam->oam[1];
 	softwareRenderer->engB.masterEnd = DS_VIDEO_HORIZONTAL_PIXELS;
+	softwareRenderer->engB.outputBufferStride = softwareRenderer->outputBufferStride;
 
 	DSVideoSoftwareRendererReset(renderer);
 }
@@ -113,6 +115,9 @@ softwareRenderer->dispcntB &= 0x0000FFFF;
 		softwareRenderer->dispcntB |= value << 16;
 		GBAVideoSoftwareRendererUpdateDISPCNTB(softwareRenderer);
 		break;
+	case DS9_REG_POWCNT1:
+		value &= 0x810F;
+		softwareRenderer->powcnt = value;
 	}
 	return value;
 }
@@ -222,11 +227,13 @@ }
 
 static void DSVideoSoftwareRendererDrawScanline(struct DSVideoRenderer* renderer, int y) {
 	struct DSVideoSoftwareRenderer* softwareRenderer = (struct DSVideoSoftwareRenderer*) renderer;
-	softwareRenderer->engA.outputBuffer = softwareRenderer->outputBuffer;
-	softwareRenderer->engB.outputBuffer = &softwareRenderer->outputBuffer[softwareRenderer->outputBufferStride * DS_VIDEO_VERTICAL_PIXELS];
-	softwareRenderer->engA.outputBufferStride = softwareRenderer->outputBufferStride;
-	softwareRenderer->engB.outputBufferStride = softwareRenderer->outputBufferStride;
-
+	if (!DSRegisterPOWCNT1IsSwap(softwareRenderer->powcnt)) {
+		softwareRenderer->engA.outputBuffer = &softwareRenderer->outputBuffer[softwareRenderer->outputBufferStride * DS_VIDEO_VERTICAL_PIXELS];
+		softwareRenderer->engB.outputBuffer = softwareRenderer->outputBuffer;
+	} else {
+		softwareRenderer->engA.outputBuffer = softwareRenderer->outputBuffer;
+		softwareRenderer->engB.outputBuffer = &softwareRenderer->outputBuffer[softwareRenderer->outputBufferStride * DS_VIDEO_VERTICAL_PIXELS];
+	}
 
 	_drawScanlineA(softwareRenderer, y);
 	_drawScanlineB(softwareRenderer, y);