all repos — mgba @ 3cfdad192c2e54ad6a94430008bf8f99c1c831cc

mGBA Game Boy Advance Emulator

GB Video: Improved video timings
Jeffrey Pfau jeffrey@endrift.com
Sun, 25 Sep 2016 19:18:46 -0700
commit

3cfdad192c2e54ad6a94430008bf8f99c1c831cc

parent

6f9a0d9758537b80df5291bd05dff26a626113ff

3 files changed, 10 insertions(+), 7 deletions(-)

jump to
M CHANGES → CHANGES 
@@ -22,6 +22,7 @@ - All: Only update version info if needed
  - FFmpeg: Encoding cleanup
  - GB Memory: Initialize RAM pattern for GBC
  - SDL: Remove scancode key input
+ - GB Video: Improved video timings
 
 0.5.0: (2016-09-19)
 Features:
M src/gb/video.c → src/gb/video.c 
@@ -110,7 +110,7 @@ ++video->ly;
 				video->p->memory.io[REG_LY] = video->ly;
 				video->stat = GBRegisterSTATSetLYC(video->stat, lyc == video->ly);
 				if (video->ly < GB_VIDEO_VERTICAL_PIXELS) {
-					video->nextMode = GB_VIDEO_MODE_2_LENGTH;
+					video->nextMode = GB_VIDEO_MODE_2_LENGTH + (video->p->memory.io[REG_SCX] & 7);
 					video->mode = 2;
 					if (!GBRegisterSTATIsHblankIRQ(video->stat) && GBRegisterSTATIsOAMIRQ(video->stat)) {
 						video->p->memory.io[REG_IF] |= (1 << GB_IRQ_LCDSTAT);

@@ -142,7 +142,8 @@ ++video->ly;
 				if (video->ly == GB_VIDEO_VERTICAL_TOTAL_PIXELS + 1) {
 					video->ly = 0;
 					video->p->memory.io[REG_LY] = video->ly;
-					video->nextMode = GB_VIDEO_MODE_2_LENGTH;
+					// TODO: Cache SCX & 7 in case it changes during mode 2
+					video->nextMode = GB_VIDEO_MODE_2_LENGTH + (video->p->memory.io[REG_SCX] & 7);
 					video->mode = 2;
 					if (GBRegisterSTATIsOAMIRQ(video->stat)) {
 						video->p->memory.io[REG_IF] |= (1 << GB_IRQ_LCDSTAT);

@@ -175,11 +176,12 @@ _cleanOAM(video, video->ly);
 				video->dotCounter = 0;
 				video->nextEvent = GB_VIDEO_HORIZONTAL_LENGTH;
 				video->x = 0;
-				video->nextMode = GB_VIDEO_MODE_3_LENGTH_BASE + video->objMax * 12;
+				// TODO: Estimate sprite timings better
+				video->nextMode = GB_VIDEO_MODE_3_LENGTH_BASE + video->objMax * 11 - (video->p->memory.io[REG_SCX] & 7);
 				video->mode = 3;
 				break;
 			case 3:
-				video->nextMode = GB_VIDEO_MODE_0_LENGTH_BASE - video->objMax * 12;
+				video->nextMode = GB_VIDEO_MODE_0_LENGTH_BASE - video->objMax * 11;
 				video->mode = 0;
 				if (GBRegisterSTATIsHblankIRQ(video->stat)) {
 					video->p->memory.io[REG_IF] |= (1 << GB_IRQ_LCDSTAT);
M src/gb/video.h → src/gb/video.h 
@@ -19,9 +19,9 @@ GB_VIDEO_VBLANK_PIXELS = 10,
 	GB_VIDEO_VERTICAL_TOTAL_PIXELS = GB_VIDEO_VERTICAL_PIXELS + GB_VIDEO_VBLANK_PIXELS,
 
 	// TODO: Figure out exact lengths
-	GB_VIDEO_MODE_2_LENGTH = 78,
-	GB_VIDEO_MODE_3_LENGTH_BASE = 160,
-	GB_VIDEO_MODE_0_LENGTH_BASE = 218,
+	GB_VIDEO_MODE_2_LENGTH = 83,
+	GB_VIDEO_MODE_3_LENGTH_BASE = 158,
+	GB_VIDEO_MODE_0_LENGTH_BASE = 215,
 
 	GB_VIDEO_HORIZONTAL_LENGTH = GB_VIDEO_MODE_0_LENGTH_BASE + GB_VIDEO_MODE_2_LENGTH + GB_VIDEO_MODE_3_LENGTH_BASE,