1/* Copyright (c) 2013-2016 Jeffrey Pfau
  2 *
  3 * This Source Code Form is subject to the terms of the Mozilla Public
  4 * License, v. 2.0. If a copy of the MPL was not distributed with this
  5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
  6#include "video.h"
  7
  8#include "gb/gb.h"
  9#include "gb/io.h"
 10
 11#include "util/memory.h"
 12
 13static void GBVideoDummyRendererInit(struct GBVideoRenderer* renderer);
 14static void GBVideoDummyRendererReset(struct GBVideoRenderer* renderer);
 15static void GBVideoDummyRendererDeinit(struct GBVideoRenderer* renderer);
 16static uint8_t GBVideoDummyRendererWriteVideoRegister(struct GBVideoRenderer* renderer, uint16_t address, uint8_t value);
 17static void GBVideoDummyRendererWriteVRAM(struct GBVideoRenderer* renderer, uint16_t address);
 18static void GBVideoDummyRendererDrawScanline(struct GBVideoRenderer* renderer, int y);
 19static void GBVideoDummyRendererFinishFrame(struct GBVideoRenderer* renderer);
 20static void GBVideoDummyRendererGetPixels(struct GBVideoRenderer* renderer, unsigned* stride, const void** pixels);
 21
 22static struct GBVideoRenderer dummyRenderer = {
 23	.init = GBVideoDummyRendererInit,
 24	.reset = GBVideoDummyRendererReset,
 25	.deinit = GBVideoDummyRendererDeinit,
 26	.writeVideoRegister = GBVideoDummyRendererWriteVideoRegister,
 27	.writeVRAM = GBVideoDummyRendererWriteVRAM,
 28	.drawScanline = GBVideoDummyRendererDrawScanline,
 29	.finishFrame = GBVideoDummyRendererFinishFrame,
 30	.getPixels = GBVideoDummyRendererGetPixels
 31};
 32
 33void GBVideoInit(struct GBVideo* video) {
 34	video->renderer = &dummyRenderer;
 35	video->vram = 0;
 36	video->frameskip = 0;
 37}
 38
 39void GBVideoReset(struct GBVideo* video) {
 40	video->ly = 0;
 41	video->mode = 1;
 42
 43	video->nextEvent = INT_MAX;
 44	video->eventDiff = 0;
 45
 46	video->nextMode = INT_MAX;
 47
 48	video->frameCounter = 0;
 49	video->frameskipCounter = 0;
 50
 51	if (video->vram) {
 52		mappedMemoryFree(video->vram, GB_SIZE_VRAM);
 53	}
 54	video->vram = anonymousMemoryMap(GB_SIZE_VRAM);
 55	video->renderer->vram = video->vram;
 56
 57	video->renderer->deinit(video->renderer);
 58	video->renderer->init(video->renderer);
 59}
 60
 61void GBVideoDeinit(struct GBVideo* video) {
 62	GBVideoAssociateRenderer(video, &dummyRenderer);
 63	mappedMemoryFree(video->vram, GB_SIZE_VRAM);
 64}
 65
 66void GBVideoAssociateRenderer(struct GBVideo* video, struct GBVideoRenderer* renderer) {
 67	// TODO
 68}
 69
 70int32_t GBVideoProcessEvents(struct GBVideo* video, int32_t cycles) {
 71	video->eventDiff += cycles;
 72	if (video->nextEvent != INT_MAX) {
 73		video->nextEvent -= cycles;
 74	}
 75	if (video->nextEvent <= 0) {
 76		if (video->nextEvent != INT_MAX) {
 77			video->nextMode -= video->eventDiff;
 78		}
 79		if (video->nextMode <= 0) {
 80			switch (video->mode) {
 81			case 0:
 82				++video->ly;
 83				video->p->memory.io[REG_LY] = video->ly;
 84				if (video->ly >= GB_VIDEO_VERTICAL_TOTAL_PIXELS) {
 85					video->ly = 0;
 86					++video->frameCounter;
 87					video->nextMode = GB_VIDEO_HORIZONTAL_LENGTH;
 88					video->mode = 1;
 89					if (GBRegisterSTATIsVblankIRQ(video->stat)) {
 90						video->p->memory.io[REG_IF] |= (1 << GB_IRQ_LCDSTAT);
 91					}
 92					video->p->memory.io[REG_IF] |= (1 << GB_IRQ_VBLANK);
 93					GBUpdateIRQs(video->p);
 94				} else {
 95					video->nextMode = GB_VIDEO_MODE_2_LENGTH;
 96					video->mode = 2;
 97					if (GBRegisterSTATIsOAMIRQ(video->stat)) {
 98						video->p->memory.io[REG_IF] |= (1 << GB_IRQ_LCDSTAT);
 99						GBUpdateIRQs(video->p);
100					}
101				}
102				break;
103			case 1:
104				video->nextMode = GB_VIDEO_MODE_2_LENGTH;
105				video->mode = 2;
106				if (GBRegisterSTATIsOAMIRQ(video->stat)) {
107					video->p->memory.io[REG_IF] |= (1 << GB_IRQ_LCDSTAT);
108					GBUpdateIRQs(video->p);
109				}
110				break;
111			case 2:
112				video->nextMode = GB_VIDEO_MODE_3_LENGTH;
113				video->mode = 3;
114				break;
115			case 3:
116				video->nextMode = GB_VIDEO_MODE_0_LENGTH;
117				video->mode = 0;
118				if (GBRegisterSTATIsHblankIRQ(video->stat)) {
119					video->p->memory.io[REG_IF] |= (1 << GB_IRQ_LCDSTAT);
120					GBUpdateIRQs(video->p);
121				}
122				break;
123			}
124			video->stat = GBRegisterSTATSetMode(video->stat, video->mode);
125			video->p->memory.io[REG_STAT] = video->stat;
126		}
127
128		video->nextEvent = video->nextMode;
129		video->eventDiff = 0;
130	}
131	return video->nextEvent;
132}
133
134void GBVideoWriteLCDC(struct GBVideo* video, GBRegisterLCDC value) {
135	if (!GBRegisterLCDCIsEnable(video->p->memory.io[REG_LCDC]) && GBRegisterLCDCIsEnable(value)) {
136		// TODO: Does enabling the LCD start in vblank?
137		video->mode = 2;
138		video->nextMode = GB_VIDEO_MODE_2_LENGTH;
139		video->nextEvent = video->nextMode;
140		video->stat = GBRegisterSTATSetMode(video->stat, video->mode);
141		video->p->memory.io[REG_STAT] = video->stat;
142		video->eventDiff = 0;
143		if (video->p->cpu->cycles + video->nextEvent < video->p->cpu->nextEvent) {
144			video->p->cpu->nextEvent = video->p->cpu->cycles + video->nextEvent;
145		}
146		return;
147	}
148	if (GBRegisterLCDCIsEnable(video->p->memory.io[REG_LCDC]) && !GBRegisterLCDCIsEnable(value)) {
149		video->mode = 0;
150		video->nextMode = INT_MAX;
151		video->nextEvent = INT_MAX;
152		video->stat = GBRegisterSTATSetMode(video->stat, video->mode);
153		video->p->memory.io[REG_STAT] = video->stat;
154		video->ly = 0;
155		video->p->memory.io[REG_LY] = 0;
156	}
157}
158
159void GBVideoWriteSTAT(struct GBVideo* video, GBRegisterSTAT value) {
160	video->stat = (video->stat & 0x7) | (value & 0x78);
161}
162
163static void GBVideoDummyRendererInit(struct GBVideoRenderer* renderer) {
164	UNUSED(renderer);
165	// Nothing to do
166}
167
168static void GBVideoDummyRendererReset(struct GBVideoRenderer* renderer) {
169	UNUSED(renderer);
170	// Nothing to do
171}
172
173static void GBVideoDummyRendererDeinit(struct GBVideoRenderer* renderer) {
174	UNUSED(renderer);
175	// Nothing to do
176}
177
178static uint8_t GBVideoDummyRendererWriteVideoRegister(struct GBVideoRenderer* renderer, uint16_t address, uint8_t value) {
179	UNUSED(renderer);
180	UNUSED(address);
181	return value;
182}
183
184static void GBVideoDummyRendererWriteVRAM(struct GBVideoRenderer* renderer, uint16_t address) {
185	UNUSED(renderer);
186	UNUSED(address);
187	// Nothing to do
188}
189
190static void GBVideoDummyRendererDrawScanline(struct GBVideoRenderer* renderer, int y) {
191	UNUSED(renderer);
192	UNUSED(y);
193	// Nothing to do
194}
195
196static void GBVideoDummyRendererFinishFrame(struct GBVideoRenderer* renderer) {
197	UNUSED(renderer);
198	// Nothing to do
199}
200
201static void GBVideoDummyRendererGetPixels(struct GBVideoRenderer* renderer, unsigned* stride, const void** pixels) {
202	UNUSED(renderer);
203	UNUSED(stride);
204	UNUSED(pixels);
205	// Nothing to do
206}