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 GBVideoDummyRendererWriteOAM(struct GBVideoRenderer* renderer, uint8_t oam);
19static void GBVideoDummyRendererDrawScanline(struct GBVideoRenderer* renderer, int y);
20static void GBVideoDummyRendererFinishFrame(struct GBVideoRenderer* renderer);
21static void GBVideoDummyRendererGetPixels(struct GBVideoRenderer* renderer, unsigned* stride, const void** pixels);
22
23static struct GBVideoRenderer dummyRenderer = {
24 .init = GBVideoDummyRendererInit,
25 .reset = GBVideoDummyRendererReset,
26 .deinit = GBVideoDummyRendererDeinit,
27 .writeVideoRegister = GBVideoDummyRendererWriteVideoRegister,
28 .writeVRAM = GBVideoDummyRendererWriteVRAM,
29 .writeOAM = GBVideoDummyRendererWriteOAM,
30 .drawScanline = GBVideoDummyRendererDrawScanline,
31 .finishFrame = GBVideoDummyRendererFinishFrame,
32 .getPixels = GBVideoDummyRendererGetPixels
33};
34
35void GBVideoInit(struct GBVideo* video) {
36 video->renderer = &dummyRenderer;
37 video->vram = 0;
38 video->frameskip = 0;
39}
40
41void GBVideoReset(struct GBVideo* video) {
42 video->ly = 0;
43 video->mode = 1;
44
45 video->nextEvent = INT_MAX;
46 video->eventDiff = 0;
47
48 video->nextMode = INT_MAX;
49
50 video->frameCounter = 0;
51 video->frameskipCounter = 0;
52
53 if (video->vram) {
54 mappedMemoryFree(video->vram, GB_SIZE_VRAM);
55 }
56 video->vram = anonymousMemoryMap(GB_SIZE_VRAM);
57 video->renderer->vram = video->vram;
58 memset(&video->oam, 0, sizeof(video->oam));
59 video->renderer->oam = &video->oam;
60
61 video->renderer->deinit(video->renderer);
62 video->renderer->init(video->renderer);
63}
64
65void GBVideoDeinit(struct GBVideo* video) {
66 GBVideoAssociateRenderer(video, &dummyRenderer);
67 mappedMemoryFree(video->vram, GB_SIZE_VRAM);
68}
69
70void GBVideoAssociateRenderer(struct GBVideo* video, struct GBVideoRenderer* renderer) {
71 video->renderer->deinit(video->renderer);
72 video->renderer = renderer;
73 renderer->vram = video->vram;
74 video->renderer->init(video->renderer);
75}
76
77int32_t GBVideoProcessEvents(struct GBVideo* video, int32_t cycles) {
78 video->eventDiff += cycles;
79 if (video->nextEvent != INT_MAX) {
80 video->nextEvent -= cycles;
81 }
82 if (video->nextEvent <= 0) {
83 if (video->nextEvent != INT_MAX) {
84 video->nextMode -= video->eventDiff;
85 }
86 if (video->nextMode <= 0) {
87 switch (video->mode) {
88 case 0:
89 ++video->ly;
90 video->p->memory.io[REG_LY] = video->ly;
91 int lyc = video->p->memory.io[REG_LYC];
92 video->stat = GBRegisterSTATSetLYC(video->stat, lyc == video->ly);
93 if (GBRegisterSTATIsLYCIRQ(video->stat) && lyc == video->ly) {
94 video->p->memory.io[REG_IF] |= (1 << GB_IRQ_LCDSTAT);
95 }
96 if (video->ly < GB_VIDEO_VERTICAL_PIXELS) {
97 video->renderer->drawScanline(video->renderer, video->ly);
98 video->nextMode = GB_VIDEO_MODE_2_LENGTH;
99 video->mode = 2;
100 if (GBRegisterSTATIsOAMIRQ(video->stat)) {
101 video->p->memory.io[REG_IF] |= (1 << GB_IRQ_LCDSTAT);
102 }
103 } else {
104 video->nextMode = GB_VIDEO_HORIZONTAL_LENGTH;
105 video->mode = 1;
106 ++video->frameCounter;
107 video->renderer->finishFrame(video->renderer);
108 if (GBRegisterSTATIsVblankIRQ(video->stat)) {
109 video->p->memory.io[REG_IF] |= (1 << GB_IRQ_LCDSTAT);
110 }
111 video->p->memory.io[REG_IF] |= (1 << GB_IRQ_VBLANK);
112 }
113 GBUpdateIRQs(video->p);
114 break;
115 case 1:
116 ++video->ly;
117 if (video->ly >= GB_VIDEO_VERTICAL_TOTAL_PIXELS) {
118 video->ly = 0;
119 video->renderer->drawScanline(video->renderer, video->ly);
120 video->nextMode = GB_VIDEO_MODE_2_LENGTH;
121 video->mode = 2;
122 if (GBRegisterSTATIsOAMIRQ(video->stat)) {
123 video->p->memory.io[REG_IF] |= (1 << GB_IRQ_LCDSTAT);
124 GBUpdateIRQs(video->p);
125 }
126 } else {
127 video->nextMode = GB_VIDEO_HORIZONTAL_LENGTH;
128 }
129 video->p->memory.io[REG_LY] = video->ly;
130 break;
131 case 2:
132 video->nextMode = GB_VIDEO_MODE_3_LENGTH;
133 video->mode = 3;
134 break;
135 case 3:
136 video->nextMode = GB_VIDEO_MODE_0_LENGTH;
137 video->mode = 0;
138 if (GBRegisterSTATIsHblankIRQ(video->stat)) {
139 video->p->memory.io[REG_IF] |= (1 << GB_IRQ_LCDSTAT);
140 GBUpdateIRQs(video->p);
141 }
142 break;
143 }
144 video->stat = GBRegisterSTATSetMode(video->stat, video->mode);
145 video->p->memory.io[REG_STAT] = video->stat;
146 }
147
148 video->nextEvent = video->nextMode;
149 video->eventDiff = 0;
150 }
151 return video->nextEvent;
152}
153
154void GBVideoWriteLCDC(struct GBVideo* video, GBRegisterLCDC value) {
155 if (!GBRegisterLCDCIsEnable(video->p->memory.io[REG_LCDC]) && GBRegisterLCDCIsEnable(value)) {
156 // TODO: Does enabling the LCD start in vblank?
157 video->mode = 2;
158 video->nextMode = GB_VIDEO_MODE_2_LENGTH;
159 video->nextEvent = video->nextMode;
160 video->eventDiff = 0;
161 video->stat = GBRegisterSTATSetMode(video->stat, video->mode);
162 video->p->memory.io[REG_STAT] = video->stat;
163 video->eventDiff = 0;
164 if (video->p->cpu->cycles + video->nextEvent < video->p->cpu->nextEvent) {
165 video->p->cpu->nextEvent = video->p->cpu->cycles + video->nextEvent;
166 }
167 return;
168 }
169 if (GBRegisterLCDCIsEnable(video->p->memory.io[REG_LCDC]) && !GBRegisterLCDCIsEnable(value)) {
170 video->mode = 0;
171 video->nextMode = INT_MAX;
172 video->nextEvent = INT_MAX;
173 video->stat = GBRegisterSTATSetMode(video->stat, video->mode);
174 video->p->memory.io[REG_STAT] = video->stat;
175 video->ly = 0;
176 video->p->memory.io[REG_LY] = 0;
177 }
178}
179
180void GBVideoWriteSTAT(struct GBVideo* video, GBRegisterSTAT value) {
181 video->stat = (video->stat & 0x7) | (value & 0x78);
182}
183
184static void GBVideoDummyRendererInit(struct GBVideoRenderer* renderer) {
185 UNUSED(renderer);
186 // Nothing to do
187}
188
189static void GBVideoDummyRendererReset(struct GBVideoRenderer* renderer) {
190 UNUSED(renderer);
191 // Nothing to do
192}
193
194static void GBVideoDummyRendererDeinit(struct GBVideoRenderer* renderer) {
195 UNUSED(renderer);
196 // Nothing to do
197}
198
199static uint8_t GBVideoDummyRendererWriteVideoRegister(struct GBVideoRenderer* renderer, uint16_t address, uint8_t value) {
200 UNUSED(renderer);
201 UNUSED(address);
202 return value;
203}
204
205static void GBVideoDummyRendererWriteVRAM(struct GBVideoRenderer* renderer, uint16_t address) {
206 UNUSED(renderer);
207 UNUSED(address);
208 // Nothing to do
209}
210
211static void GBVideoDummyRendererWriteOAM(struct GBVideoRenderer* renderer, uint8_t oam) {
212 UNUSED(renderer);
213 UNUSED(oam);
214 // Nothing to do
215}
216
217static void GBVideoDummyRendererDrawScanline(struct GBVideoRenderer* renderer, int y) {
218 UNUSED(renderer);
219 UNUSED(y);
220 // Nothing to do
221}
222
223static void GBVideoDummyRendererFinishFrame(struct GBVideoRenderer* renderer) {
224 UNUSED(renderer);
225 // Nothing to do
226}
227
228static void GBVideoDummyRendererGetPixels(struct GBVideoRenderer* renderer, unsigned* stride, const void** pixels) {
229 UNUSED(renderer);
230 UNUSED(stride);
231 UNUSED(pixels);
232 // Nothing to do
233}