GBA Video: Implement naive cycle counting for sprite rendering

CHANGES

@@ -14,6 +14,7 @@ Features:
  - OpenEmu core for OS X
  - Libretro: Settings for using BIOS and skipping intro
  - Libretro: Customizable idle loop removal
+ - Implemented cycle counting for sprite rendering
 Bugfixes:
  - Util: Fix PowerPC PNG read/write pixel order
  - VFS: Fix VFileReadline and remove _vfdReadline

src/gba/renderers/software-obj.c

@@ -178,6 +178,10 @@ int GBAVideoSoftwareRendererPreprocessSprite(struct GBAVideoSoftwareRenderer* re
 	if (GBAObjAttributesAIsTransformed(sprite->a)) {
 		int totalWidth = width << GBAObjAttributesAGetDoubleSize(sprite->a);
 		int totalHeight = height << GBAObjAttributesAGetDoubleSize(sprite->a);
+		renderer->spriteCyclesRemaining -= 10 + totalWidth * 2;
+		if (renderer->spriteCyclesRemaining <= 0) {
+			return 0;
+		}
 		struct GBAOAMMatrix mat;
 		LOAD_16(mat.a, 0, &renderer->d.oam->mat[GBAObjAttributesBGetMatIndex(sprite->b)].a);
 		LOAD_16(mat.b, 0, &renderer->d.oam->mat[GBAObjAttributesBGetMatIndex(sprite->b)].b);
@@ -212,6 +216,10 @@ int GBAVideoSoftwareRendererPreprocessSprite(struct GBAVideoSoftwareRenderer* re
 			}
 		}
 	} else {
+		renderer->spriteCyclesRemaining -= width;
+		if (renderer->spriteCyclesRemaining <= 0) {
+			return 0;
+		}
 		int outX = x >= start ? x : start;
 		int condition = x + width;
 		int mosaicH = 1;

src/gba/renderers/video-software.c

@@ -748,6 +748,7 @@ static void _drawScanline(struct GBAVideoSoftwareRenderer* renderer, int y) {
 		if (renderer->oamDirty) {
 			_cleanOAM(renderer);
 		}
+		renderer->spriteCyclesRemaining = GBARegisterDISPCNTIsHblankIntervalFree(renderer->dispcnt) ? OBJ_HBLANK_FREE_LENGTH : OBJ_LENGTH;
 		int mosaicV = GBAMosaicControlGetObjV(renderer->mosaic) + 1;
 		int mosaicY = y - (y % mosaicV);
 		for (w = 0; w < renderer->nWindows; ++w) {
@@ -761,6 +762,9 @@ static void _drawScanline(struct GBAVideoSoftwareRenderer* renderer, int y) {
 			int drawn;
 			for (i = 0; i < renderer->oamMax; ++i) {
 				int localY = y;
+				if (renderer->spriteCyclesRemaining <= 0) {
+					break;
+				}
 				struct GBAVideoSoftwareSprite* sprite = &renderer->sprites[i];
 				if (GBAObjAttributesAIsMosaic(sprite->obj.a)) {
 					localY = mosaicY;

src/gba/renderers/video-software.h

@@ -122,6 +122,7 @@ struct GBAVideoSoftwareRenderer {
 
 	uint32_t row[VIDEO_HORIZONTAL_PIXELS];
 	uint32_t spriteLayer[VIDEO_HORIZONTAL_PIXELS];
+	int32_t spriteCyclesRemaining;
 
 	// BLDCNT
 	unsigned target1Obj;

src/gba/video.h

@@ -38,6 +38,9 @@ enum {
 
 	VIDEO_TOTAL_LENGTH = VIDEO_HORIZONTAL_LENGTH * VIDEO_VERTICAL_TOTAL_PIXELS,
 
+	OBJ_HBLANK_FREE_LENGTH = 954,
+	OBJ_LENGTH = 1210,
+
 	BASE_TILE = 0x00010000
 };