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			video->mode = (video->mode + 1) & 3;
 81			switch (video->mode) {
 82			case 0:
 83				video->nextMode = GB_VIDEO_MODE_0_LENGTH;
 84				break;
 85			case 1:
 86				video->nextMode = GB_VIDEO_MODE_1_LENGTH;
 87				break;
 88			case 2:
 89				video->nextMode = GB_VIDEO_MODE_2_LENGTH;
 90				++video->ly;
 91				if (video->ly >= GB_VIDEO_VERTICAL_TOTAL_PIXELS) {
 92					video->ly = 0;
 93					++video->frameCounter;
 94				}
 95				video->p->memory.io[REG_LY] = video->ly;
 96				break;
 97			case 3:
 98				video->nextMode = GB_VIDEO_MODE_3_LENGTH;
 99				break;
100			}
101		}
102
103		video->nextEvent = video->nextMode;
104		video->eventDiff = 0;
105	}
106	return video->nextEvent;
107}
108
109void GBVideoWriteLCDC(struct GBVideo* video, GBRegisterLCDC value) {
110	if (!GBRegisterLCDCIsEnable(video->p->memory.io[REG_LCDC]) && GBRegisterLCDCIsEnable(value)) {
111		// TODO: Does enabling the LCD start in vblank?
112		video->mode = 2;
113		video->nextMode = GB_VIDEO_MODE_2_LENGTH;
114		video->nextEvent = video->nextMode;
115		video->eventDiff = 0;
116		if (video->nextEvent < video->p->cpu->nextEvent) {
117			video->p->cpu->nextEvent = video->nextEvent;
118		}
119		return;
120	}
121}
122
123static void GBVideoDummyRendererInit(struct GBVideoRenderer* renderer) {
124	UNUSED(renderer);
125	// Nothing to do
126}
127
128static void GBVideoDummyRendererReset(struct GBVideoRenderer* renderer) {
129	UNUSED(renderer);
130	// Nothing to do
131}
132
133static void GBVideoDummyRendererDeinit(struct GBVideoRenderer* renderer) {
134	UNUSED(renderer);
135	// Nothing to do
136}
137
138static uint8_t GBVideoDummyRendererWriteVideoRegister(struct GBVideoRenderer* renderer, uint16_t address, uint8_t value) {
139	UNUSED(renderer);
140	UNUSED(address);
141	return value;
142}
143
144static void GBVideoDummyRendererWriteVRAM(struct GBVideoRenderer* renderer, uint16_t address) {
145	UNUSED(renderer);
146	UNUSED(address);
147	// Nothing to do
148}
149
150static void GBVideoDummyRendererDrawScanline(struct GBVideoRenderer* renderer, int y) {
151	UNUSED(renderer);
152	UNUSED(y);
153	// Nothing to do
154}
155
156static void GBVideoDummyRendererFinishFrame(struct GBVideoRenderer* renderer) {
157	UNUSED(renderer);
158	// Nothing to do
159}
160
161static void GBVideoDummyRendererGetPixels(struct GBVideoRenderer* renderer, unsigned* stride, const void** pixels) {
162	UNUSED(renderer);
163	UNUSED(stride);
164	UNUSED(pixels);
165	// Nothing to do
166}