1#include "gba-video.h"
  2
  3#include "gba.h"
  4#include "gba-io.h"
  5
  6#include <limits.h>
  7#include <string.h>
  8#include <sys/mman.h>
  9
 10static void GBAVideoDummyRendererInit(struct GBAVideoRenderer* renderer);
 11static void GBAVideoDummyRendererDeinit(struct GBAVideoRenderer* renderer);
 12static uint16_t GBAVideoDummyRendererWriteVideoRegister(struct GBAVideoRenderer* renderer, uint32_t address, uint16_t value);
 13static void GBAVideoDummyRendererDrawScanline(struct GBAVideoRenderer* renderer, int y);
 14static void GBAVideoDummyRendererFinishFrame(struct GBAVideoRenderer* renderer);
 15
 16static struct GBAVideoRenderer dummyRenderer = {
 17	.init = GBAVideoDummyRendererInit,
 18	.deinit = GBAVideoDummyRendererDeinit,
 19	.writeVideoRegister = GBAVideoDummyRendererWriteVideoRegister,
 20	.drawScanline = GBAVideoDummyRendererDrawScanline,
 21	.finishFrame = GBAVideoDummyRendererFinishFrame
 22};
 23
 24void GBAVideoInit(struct GBAVideo* video) {
 25	video->renderer = &dummyRenderer;
 26
 27	video->inHblank = 0;
 28	video->inVblank = 0;
 29	video->vcounter = 0;
 30	video->vblankIRQ = 0;
 31	video->hblankIRQ = 0;
 32	video->vcounterIRQ = 0;
 33	video->vcountSetting = 0;
 34
 35	video->vcount = -1;
 36
 37	video->lastHblank = 0;
 38	video->nextHblank = VIDEO_HDRAW_LENGTH;
 39	video->nextEvent = video->nextHblank;
 40	video->eventDiff = video->nextEvent;
 41
 42	video->nextHblankIRQ = 0;
 43	video->nextVblankIRQ = 0;
 44	video->nextVcounterIRQ = 0;
 45
 46	video->vram = mmap(0, SIZE_VRAM, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON, -1, 0);
 47}
 48
 49void GBAVideoDeinit(struct GBAVideo* video) {
 50	GBAVideoAssociateRenderer(video, &dummyRenderer);
 51	munmap(video->vram, SIZE_VRAM);
 52}
 53
 54void GBAVideoAssociateRenderer(struct GBAVideo* video, struct GBAVideoRenderer* renderer) {
 55	video->renderer->deinit(video->renderer);
 56	video->renderer = renderer;
 57	renderer->palette = video->palette;
 58	renderer->vram = video->vram;
 59	renderer->oam = &video->oam;
 60	video->renderer->init(video->renderer);
 61}
 62
 63int32_t GBAVideoProcessEvents(struct GBAVideo* video, int32_t cycles) {
 64	video->nextEvent -= cycles;
 65	if (video->nextEvent <= 0) {
 66		video->lastHblank -= video->eventDiff;
 67		video->nextHblank -= video->eventDiff;
 68		video->nextHblankIRQ -= video->eventDiff;
 69		video->nextVcounterIRQ -= video->eventDiff;
 70
 71		if (video->inHblank) {
 72			// End Hblank
 73			video->inHblank = 0;
 74			video->nextEvent = video->nextHblank;
 75
 76			++video->vcount;
 77			video->p->memory.io[REG_VCOUNT >> 1] = video->vcount;
 78
 79			switch (video->vcount) {
 80			case VIDEO_VERTICAL_PIXELS:
 81				video->inVblank = 1;
 82				video->renderer->finishFrame(video->renderer);
 83				video->nextVblankIRQ = video->nextEvent + VIDEO_TOTAL_LENGTH;
 84				GBAMemoryRunVblankDMAs(&video->p->memory);
 85				if (video->vblankIRQ) {
 86					GBARaiseIRQ(video->p, IRQ_VBLANK);
 87				}
 88				//video->vblankCallback();
 89				break;
 90			case VIDEO_VERTICAL_TOTAL_PIXELS - 1:
 91				video->inVblank = 0;
 92				break;
 93			case VIDEO_VERTICAL_TOTAL_PIXELS:
 94				video->vcount = 0;
 95				//video->renderPath.startDraw();
 96				break;
 97			}
 98
 99			video->vcounter = video->vcount == video->vcountSetting;
100			if (video->vcounter && video->vcounterIRQ) {
101				GBARaiseIRQ(video->p, IRQ_VCOUNTER);
102				video->nextVcounterIRQ += VIDEO_TOTAL_LENGTH;
103			}
104
105			if (video->vcount < VIDEO_VERTICAL_PIXELS) {
106				video->renderer->drawScanline(video->renderer, video->vcount);
107			}
108		} else {
109			// Begin Hblank
110			video->inHblank = 1;
111			video->lastHblank = video->nextHblank;
112			video->nextEvent = video->lastHblank + VIDEO_HBLANK_LENGTH;
113			video->nextHblank = video->nextEvent + VIDEO_HDRAW_LENGTH;
114			video->nextHblankIRQ = video->nextHblank;
115
116			if (video->vcount < VIDEO_VERTICAL_PIXELS) {
117				GBAMemoryRunHblankDMAs(&video->p->memory);
118			}
119			if (video->hblankIRQ) {
120				GBARaiseIRQ(video->p, IRQ_HBLANK);
121			}
122		}
123
124		video->eventDiff = video->nextEvent;
125	}
126	return video->nextEvent;
127}
128
129void GBAVideoWriteDISPSTAT(struct GBAVideo* video, uint16_t value) {
130	video->vblankIRQ = value & 0x0008;
131	video->hblankIRQ = value & 0x0010;
132	video->vcounterIRQ = value & 0x0020;
133	video->vcountSetting = (value & 0xFF00) >> 8;
134
135	if (video->vcounterIRQ) {
136		// FIXME: this can be too late if we're in the middle of an Hblank
137		video->nextVcounterIRQ = video->nextHblank + VIDEO_HBLANK_LENGTH + (video->vcountSetting - video->vcount) * VIDEO_HORIZONTAL_LENGTH;
138		if (video->nextVcounterIRQ < video->nextEvent) {
139			video->nextVcounterIRQ += VIDEO_TOTAL_LENGTH;
140		}
141	}
142}
143
144uint16_t GBAVideoReadDISPSTAT(struct GBAVideo* video) {
145	return (video->inVblank) | (video->inHblank << 1) | (video->vcounter << 2);
146}
147
148static void GBAVideoDummyRendererInit(struct GBAVideoRenderer* renderer) {
149	(void)(renderer);
150	// Nothing to do
151}
152
153static void GBAVideoDummyRendererDeinit(struct GBAVideoRenderer* renderer) {
154	(void)(renderer);
155	// Nothing to do
156}
157
158static uint16_t GBAVideoDummyRendererWriteVideoRegister(struct GBAVideoRenderer* renderer, uint32_t address, uint16_t value) {
159	(void)(renderer);
160	(void)(address);
161	return value;
162}
163
164static void GBAVideoDummyRendererDrawScanline(struct GBAVideoRenderer* renderer, int y) {
165	(void)(renderer);
166	(void)(y);
167	// Nothing to do
168}
169
170static void GBAVideoDummyRendererFinishFrame(struct GBAVideoRenderer* renderer) {
171	(void)(renderer);
172	// Nothing to do
173}