1#include "gba-video.h"
  2
  3#include "gba.h"
  4
  5#include <limits.h>
  6
  7static void GBAVideoDummyRendererInit(struct GBAVideoRenderer* renderer);
  8static void GBAVideoDummyRendererDeinit(struct GBAVideoRenderer* renderer);
  9static uint16_t GBAVideoDummyRendererWriteVideoRegister(struct GBAVideoRenderer* renderer, uint32_t address, uint16_t value);
 10static void GBAVideoDummyRendererDrawScanline(struct GBAVideoRenderer* renderer, int y);
 11static void GBAVideoDummyRendererFinishFrame(struct GBAVideoRenderer* renderer);
 12
 13static struct GBAVideoRenderer dummyRenderer = {
 14	.init = GBAVideoDummyRendererInit,
 15	.deinit = GBAVideoDummyRendererDeinit,
 16	.writeVideoRegister = GBAVideoDummyRendererWriteVideoRegister,
 17	.drawScanline = GBAVideoDummyRendererDrawScanline,
 18	.finishFrame = GBAVideoDummyRendererFinishFrame
 19};
 20
 21void GBAVideoInit(struct GBAVideo* video) {
 22	video->renderer = &dummyRenderer;
 23
 24	video->inHblank = 0;
 25	video->inVblank = 0;
 26	video->vcounter = 0;
 27	video->vblankIRQ = 0;
 28	video->hblankIRQ = 0;
 29	video->vcounterIRQ = 0;
 30	video->vcountSetting = 0;
 31
 32	video->vcount = -1;
 33
 34	video->lastHblank = 0;
 35	video->nextHblank = VIDEO_HDRAW_LENGTH;
 36	video->nextEvent = video->nextHblank;
 37	video->eventDiff = video->nextEvent;
 38
 39	video->nextHblankIRQ = 0;
 40	video->nextVblankIRQ = 0;
 41	video->nextVcounterIRQ = 0;
 42}
 43
 44int32_t GBAVideoProcessEvents(struct GBAVideo* video, int32_t cycles) {
 45	video->nextEvent -= cycles;
 46	if (video->nextEvent <= 0) {
 47		video->lastHblank -= video->eventDiff;
 48		video->nextHblank -= video->eventDiff;
 49		video->nextHblankIRQ -= video->eventDiff;
 50		video->nextVcounterIRQ -= video->eventDiff;
 51
 52		if (video->inHblank) {
 53			// End Hblank
 54			video->inHblank = 0;
 55			video->nextEvent = video->nextHblank;
 56
 57			++video->vcount;
 58
 59			switch (video->vcount) {
 60			case VIDEO_VERTICAL_PIXELS:
 61				video->inVblank = 1;
 62				video->renderer->finishFrame(video->renderer);
 63				video->nextVblankIRQ = video->nextEvent + VIDEO_TOTAL_LENGTH;
 64				//video->cpu.mmu.runVblankDmas();
 65				if (video->vblankIRQ) {
 66					GBARaiseIRQ(video->p, IRQ_VBLANK);
 67				}
 68				//video->vblankCallback();
 69				break;
 70			case VIDEO_VERTICAL_TOTAL_PIXELS - 1:
 71				video->inVblank = 0;
 72				break;
 73			case VIDEO_VERTICAL_TOTAL_PIXELS:
 74				video->vcount = 0;
 75				//video->renderPath.startDraw();
 76				break;
 77			}
 78
 79			video->vcounter = video->vcount == video->vcountSetting;
 80			if (video->vcounter && video->vcounterIRQ) {
 81				GBARaiseIRQ(video->p, IRQ_VCOUNTER);
 82				video->nextVcounterIRQ += VIDEO_TOTAL_LENGTH;
 83			}
 84
 85			if (video->vcount < VIDEO_VERTICAL_PIXELS) {
 86				video->renderer->drawScanline(video->renderer, video->vcount);
 87			}
 88		} else {
 89			// Begin Hblank
 90			video->inHblank = 1;
 91			video->lastHblank = video->nextHblank;
 92			video->nextEvent = video->lastHblank + VIDEO_HBLANK_LENGTH;
 93			video->nextHblank = video->nextEvent + VIDEO_HDRAW_LENGTH;
 94			video->nextHblankIRQ = video->nextHblank;
 95
 96			if (video->vcount < VIDEO_VERTICAL_PIXELS) {
 97				//video->cpu.mmu.runHblankDmas();
 98			}
 99			if (video->hblankIRQ) {
100				GBARaiseIRQ(video->p, IRQ_HBLANK);
101			}
102		}
103
104		video->eventDiff = video->nextEvent;
105	}
106	return video->nextEvent;
107}
108
109void GBAVideoWriteDISPSTAT(struct GBAVideo* video, uint16_t value) {
110	video->vblankIRQ = value & 0x0008;
111	video->hblankIRQ = value & 0x0010;
112	video->vcounterIRQ = value & 0x0020;
113	video->vcountSetting = (value & 0xFF00) >> 8;
114
115	if (video->vcounterIRQ) {
116		// FIXME: this can be too late if we're in the middle of an Hblank
117		video->nextVcounterIRQ = video->nextHblank + VIDEO_HBLANK_LENGTH + (video->vcountSetting - video->vcount) * VIDEO_HORIZONTAL_LENGTH;
118		if (video->nextVcounterIRQ < video->nextEvent) {
119			video->nextVcounterIRQ += VIDEO_TOTAL_LENGTH;
120		}
121	}
122}
123
124uint16_t GBAVideoReadDISPSTAT(struct GBAVideo* video) {
125	return (video->inVblank) | (video->inHblank << 1) | (video->vcounter << 2);
126}
127
128static void GBAVideoDummyRendererInit(struct GBAVideoRenderer* renderer) {
129	(void)(renderer);
130	// Nothing to do
131}
132
133static void GBAVideoDummyRendererDeinit(struct GBAVideoRenderer* renderer) {
134	(void)(renderer);
135	// Nothing to do
136}
137static uint16_t GBAVideoDummyRendererWriteVideoRegister(struct GBAVideoRenderer* renderer, uint32_t address, uint16_t value) {
138	(void)(renderer);
139	(void)(address);
140	return value;
141}
142
143static void GBAVideoDummyRendererDrawScanline(struct GBAVideoRenderer* renderer, int y) {
144	(void)(renderer);
145	(void)(y);
146	// Nothing to do
147}
148
149static void GBAVideoDummyRendererFinishFrame(struct GBAVideoRenderer* renderer) {
150	(void)(renderer);
151	printf("Drawing a frame\n");
152	// Nothing to do
153}