src/gb/video.c (view raw)
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 video->renderer->deinit(video->renderer);
68 video->renderer = renderer;
69 renderer->vram = video->vram;
70 video->renderer->init(video->renderer);
71}
72
73int32_t GBVideoProcessEvents(struct GBVideo* video, int32_t cycles) {
74 video->eventDiff += cycles;
75 if (video->nextEvent != INT_MAX) {
76 video->nextEvent -= cycles;
77 }
78 if (video->nextEvent <= 0) {
79 if (video->nextEvent != INT_MAX) {
80 video->nextMode -= video->eventDiff;
81 }
82 if (video->nextMode <= 0) {
83 switch (video->mode) {
84 case 0:
85 ++video->ly;
86 video->p->memory.io[REG_LY] = video->ly;
87 if (video->ly < GB_VIDEO_VERTICAL_PIXELS) {
88 video->renderer->drawScanline(video->renderer, video->ly);
89 video->nextMode = GB_VIDEO_MODE_2_LENGTH;
90 video->mode = 2;
91 if (GBRegisterSTATIsOAMIRQ(video->stat)) {
92 video->p->memory.io[REG_IF] |= (1 << GB_IRQ_LCDSTAT);
93 GBUpdateIRQs(video->p);
94 }
95 } else {
96 video->nextMode = GB_VIDEO_HORIZONTAL_LENGTH;
97 video->mode = 1;
98 ++video->frameCounter;
99 video->renderer->finishFrame(video->renderer);
100 if (GBRegisterSTATIsVblankIRQ(video->stat)) {
101 video->p->memory.io[REG_IF] |= (1 << GB_IRQ_LCDSTAT);
102 }
103 video->p->memory.io[REG_IF] |= (1 << GB_IRQ_VBLANK);
104 GBUpdateIRQs(video->p);
105 }
106 break;
107 case 1:
108 ++video->ly;
109 if (video->ly >= GB_VIDEO_VERTICAL_TOTAL_PIXELS) {
110 video->ly = 0;
111 video->nextMode = GB_VIDEO_MODE_2_LENGTH;
112 video->mode = 2;
113 if (GBRegisterSTATIsOAMIRQ(video->stat)) {
114 video->p->memory.io[REG_IF] |= (1 << GB_IRQ_LCDSTAT);
115 GBUpdateIRQs(video->p);
116 }
117 } else {
118 video->nextMode = GB_VIDEO_HORIZONTAL_LENGTH;
119 }
120 video->p->memory.io[REG_LY] = video->ly;
121 break;
122 case 2:
123 video->nextMode = GB_VIDEO_MODE_3_LENGTH;
124 video->mode = 3;
125 break;
126 case 3:
127 video->nextMode = GB_VIDEO_MODE_0_LENGTH;
128 video->mode = 0;
129 if (GBRegisterSTATIsHblankIRQ(video->stat)) {
130 video->p->memory.io[REG_IF] |= (1 << GB_IRQ_LCDSTAT);
131 GBUpdateIRQs(video->p);
132 }
133 break;
134 }
135 video->stat = GBRegisterSTATSetMode(video->stat, video->mode);
136 video->p->memory.io[REG_STAT] = video->stat;
137 }
138
139 video->nextEvent = video->nextMode;
140 video->eventDiff = 0;
141 }
142 return video->nextEvent;
143}
144
145void GBVideoWriteLCDC(struct GBVideo* video, GBRegisterLCDC value) {
146 if (!GBRegisterLCDCIsEnable(video->p->memory.io[REG_LCDC]) && GBRegisterLCDCIsEnable(value)) {
147 // TODO: Does enabling the LCD start in vblank?
148 video->mode = 2;
149 video->nextMode = GB_VIDEO_MODE_2_LENGTH;
150 video->nextEvent = video->nextMode;
151 video->eventDiff = 0;
152 video->stat = GBRegisterSTATSetMode(video->stat, video->mode);
153 video->p->memory.io[REG_STAT] = video->stat;
154 video->eventDiff = 0;
155 if (video->p->cpu->cycles + video->nextEvent < video->p->cpu->nextEvent) {
156 video->p->cpu->nextEvent = video->p->cpu->cycles + video->nextEvent;
157 }
158 return;
159 }
160 if (GBRegisterLCDCIsEnable(video->p->memory.io[REG_LCDC]) && !GBRegisterLCDCIsEnable(value)) {
161 video->mode = 0;
162 video->nextMode = INT_MAX;
163 video->nextEvent = INT_MAX;
164 video->stat = GBRegisterSTATSetMode(video->stat, video->mode);
165 video->p->memory.io[REG_STAT] = video->stat;
166 video->ly = 0;
167 video->p->memory.io[REG_LY] = 0;
168 }
169}
170
171void GBVideoWriteSTAT(struct GBVideo* video, GBRegisterSTAT value) {
172 video->stat = (video->stat & 0x7) | (value & 0x78);
173}
174
175static void GBVideoDummyRendererInit(struct GBVideoRenderer* renderer) {
176 UNUSED(renderer);
177 // Nothing to do
178}
179
180static void GBVideoDummyRendererReset(struct GBVideoRenderer* renderer) {
181 UNUSED(renderer);
182 // Nothing to do
183}
184
185static void GBVideoDummyRendererDeinit(struct GBVideoRenderer* renderer) {
186 UNUSED(renderer);
187 // Nothing to do
188}
189
190static uint8_t GBVideoDummyRendererWriteVideoRegister(struct GBVideoRenderer* renderer, uint16_t address, uint8_t value) {
191 UNUSED(renderer);
192 UNUSED(address);
193 return value;
194}
195
196static void GBVideoDummyRendererWriteVRAM(struct GBVideoRenderer* renderer, uint16_t address) {
197 UNUSED(renderer);
198 UNUSED(address);
199 // Nothing to do
200}
201
202static void GBVideoDummyRendererDrawScanline(struct GBVideoRenderer* renderer, int y) {
203 UNUSED(renderer);
204 UNUSED(y);
205 // Nothing to do
206}
207
208static void GBVideoDummyRendererFinishFrame(struct GBVideoRenderer* renderer) {
209 UNUSED(renderer);
210 // Nothing to do
211}
212
213static void GBVideoDummyRendererGetPixels(struct GBVideoRenderer* renderer, unsigned* stride, const void** pixels) {
214 UNUSED(renderer);
215 UNUSED(stride);
216 UNUSED(pixels);
217 // Nothing to do
218}