src/gb/gb.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 "gb.h"
7
8#include "gb/io.h"
9
10#include "core/core.h"
11#include "util/crc32.h"
12#include "util/memory.h"
13#include "util/math.h"
14#include "util/patch.h"
15#include "util/vfs.h"
16
17const uint32_t CGB_LR35902_FREQUENCY = 0x800000;
18const uint32_t SGB_LR35902_FREQUENCY = 0x418B1E;
19
20const uint32_t GB_COMPONENT_MAGIC = 0x400000;
21
22mLOG_DEFINE_CATEGORY(GB, "GB");
23
24static void GBInit(void* cpu, struct mCPUComponent* component);
25static void GBInterruptHandlerInit(struct LR35902InterruptHandler* irqh);
26static void GBProcessEvents(struct LR35902Core* cpu);
27static void GBSetInterrupts(struct LR35902Core* cpu, bool enable);
28static void GBIllegal(struct LR35902Core* cpu);
29static void GBHitStub(struct LR35902Core* cpu);
30
31#ifdef _3DS
32extern uint32_t* romBuffer;
33extern size_t romBufferSize;
34#endif
35
36void GBCreate(struct GB* gb) {
37 gb->d.id = GB_COMPONENT_MAGIC;
38 gb->d.init = GBInit;
39 gb->d.deinit = 0;
40}
41
42static void GBInit(void* cpu, struct mCPUComponent* component) {
43 struct GB* gb = (struct GB*) component;
44 gb->cpu = cpu;
45
46 GBInterruptHandlerInit(&gb->cpu->irqh);
47 GBMemoryInit(gb);
48
49 gb->video.p = gb;
50 GBVideoInit(&gb->video);
51
52 gb->audio.p = gb;
53 GBAudioInit(&gb->audio, 2048, &gb->memory.io[REG_NR52], GB_AUDIO_DMG); // TODO: Remove magic constant
54
55 gb->timer.p = gb;
56
57 gb->romVf = 0;
58 gb->sramVf = 0;
59
60 gb->pristineRom = 0;
61 gb->pristineRomSize = 0;
62 gb->yankedRomSize = 0;
63
64 gb->eiPending = false;
65 gb->doubleSpeed = 0;
66}
67
68bool GBLoadROM(struct GB* gb, struct VFile* vf) {
69 GBUnloadROM(gb);
70 gb->romVf = vf;
71 gb->pristineRomSize = vf->size(vf);
72 vf->seek(vf, 0, SEEK_SET);
73#ifdef _3DS
74 gb->pristineRom = 0;
75 if (gb->pristineRomSize <= romBufferSize) {
76 gb->pristineRom = romBuffer;
77 vf->read(vf, romBuffer, gb->pristineRomSize);
78 }
79#else
80 gb->pristineRom = vf->map(vf, gb->pristineRomSize, MAP_READ);
81#endif
82 if (!gb->pristineRom) {
83 return false;
84 }
85 gb->yankedRomSize = 0;
86 gb->memory.rom = gb->pristineRom;
87 gb->memory.romSize = gb->pristineRomSize;
88 gb->romCrc32 = doCrc32(gb->memory.rom, gb->memory.romSize);
89
90 // TODO: error check
91 return true;
92}
93
94bool GBLoadSave(struct GB* gb, struct VFile* vf) {
95 gb->sramVf = vf;
96 if (vf) {
97 // TODO: Do this in bank-switching code
98 if (vf->size(vf) < 0x20000) {
99 vf->truncate(vf, 0x20000);
100 }
101 gb->memory.sram = vf->map(vf, 0x20000, MAP_WRITE);
102 } else {
103 gb->memory.sram = anonymousMemoryMap(0x20000);
104 }
105 return gb->memory.sram;
106}
107
108void GBUnloadROM(struct GB* gb) {
109 // TODO: Share with GBAUnloadROM
110 if (gb->memory.rom && gb->pristineRom != gb->memory.rom) {
111 if (gb->yankedRomSize) {
112 gb->yankedRomSize = 0;
113 }
114 mappedMemoryFree(gb->memory.rom, 0x400000);
115 }
116 gb->memory.rom = 0;
117
118 if (gb->romVf) {
119#ifndef _3DS
120 gb->romVf->unmap(gb->romVf, gb->pristineRom, gb->pristineRomSize);
121#endif
122 gb->pristineRom = 0;
123 gb->romVf = 0;
124 }
125
126 if (gb->sramVf) {
127 gb->sramVf->unmap(gb->sramVf, gb->memory.sram, 0x8000);
128 gb->sramVf = 0;
129 } else if (gb->memory.sram) {
130 mappedMemoryFree(gb->memory.sram, 0x8000);
131 }
132 gb->memory.sram = 0;
133}
134
135void GBApplyPatch(struct GB* gb, struct Patch* patch) {
136 size_t patchedSize = patch->outputSize(patch, gb->memory.romSize);
137 if (!patchedSize) {
138 return;
139 }
140 if (patchedSize > 0x400000) {
141 patchedSize = 0x400000;
142 }
143 gb->memory.rom = anonymousMemoryMap(0x400000);
144 if (!patch->applyPatch(patch, gb->pristineRom, gb->pristineRomSize, gb->memory.rom, patchedSize)) {
145 mappedMemoryFree(gb->memory.rom, patchedSize);
146 gb->memory.rom = gb->pristineRom;
147 return;
148 }
149 gb->memory.romSize = patchedSize;
150 gb->romCrc32 = doCrc32(gb->memory.rom, gb->memory.romSize);
151}
152
153void GBDestroy(struct GB* gb) {
154 GBUnloadROM(gb);
155
156 GBMemoryDeinit(gb);
157}
158
159void GBInterruptHandlerInit(struct LR35902InterruptHandler* irqh) {
160 irqh->reset = GBReset;
161 irqh->processEvents = GBProcessEvents;
162 irqh->setInterrupts = GBSetInterrupts;
163 irqh->hitIllegal = GBIllegal;
164 irqh->stop = GBStop;
165 irqh->halt = GBHalt;
166}
167
168void GBReset(struct LR35902Core* cpu) {
169 struct GB* gb = (struct GB*) cpu->master;
170
171 const struct GBCartridge* cart = (const struct GBCartridge*) &gb->memory.rom[0x100];
172 if (cart->cgb & 0x80) {
173 gb->model = GB_MODEL_CGB;
174 gb->audio.style = GB_AUDIO_CGB;
175 cpu->a = 0x11;
176 } else {
177 // TODO: SGB
178 gb->model = GB_MODEL_DMG;
179 gb->audio.style = GB_AUDIO_DMG;
180 cpu->a = 1;
181 }
182
183 cpu->f.packed = 0xB0;
184 cpu->b = 0;
185 cpu->c = 0x13;
186 cpu->d = 0;
187 cpu->e = 0xD8;
188 cpu->h = 1;
189 cpu->l = 0x4D;
190 cpu->sp = 0xFFFE;
191 cpu->pc = 0x100;
192
193 if (gb->yankedRomSize) {
194 gb->memory.romSize = gb->yankedRomSize;
195 gb->yankedRomSize = 0;
196 }
197 GBMemoryReset(gb);
198 GBVideoReset(&gb->video);
199 GBTimerReset(&gb->timer);
200 GBIOReset(gb);
201 GBAudioReset(&gb->audio);
202}
203
204void GBUpdateIRQs(struct GB* gb) {
205 int irqs = gb->memory.ie & gb->memory.io[REG_IF];
206 if (!irqs) {
207 return;
208 }
209 gb->cpu->halted = false;
210
211 if (!gb->memory.ime) {
212 return;
213 }
214
215 if (irqs & (1 << GB_IRQ_VBLANK)) {
216 LR35902RaiseIRQ(gb->cpu, GB_VECTOR_VBLANK);
217 gb->memory.io[REG_IF] &= ~(1 << GB_IRQ_VBLANK);
218 return;
219 }
220 if (irqs & (1 << GB_IRQ_LCDSTAT)) {
221 LR35902RaiseIRQ(gb->cpu, GB_VECTOR_LCDSTAT);
222 gb->memory.io[REG_IF] &= ~(1 << GB_IRQ_LCDSTAT);
223 return;
224 }
225 if (irqs & (1 << GB_IRQ_TIMER)) {
226 LR35902RaiseIRQ(gb->cpu, GB_VECTOR_TIMER);
227 gb->memory.io[REG_IF] &= ~(1 << GB_IRQ_TIMER);
228 return;
229 }
230 if (irqs & (1 << GB_IRQ_SIO)) {
231 LR35902RaiseIRQ(gb->cpu, GB_VECTOR_SIO);
232 gb->memory.io[REG_IF] &= ~(1 << GB_IRQ_SIO);
233 return;
234 }
235 if (irqs & (1 << GB_IRQ_KEYPAD)) {
236 LR35902RaiseIRQ(gb->cpu, GB_VECTOR_KEYPAD);
237 gb->memory.io[REG_IF] &= ~(1 << GB_IRQ_KEYPAD);
238 }
239}
240
241void GBProcessEvents(struct LR35902Core* cpu) {
242 struct GB* gb = (struct GB*) cpu->master;
243 do {
244 int32_t cycles = cpu->nextEvent;
245 int32_t nextEvent = INT_MAX;
246 int32_t testEvent;
247
248 if (gb->eiPending) {
249 gb->eiPending -= cycles;
250 if (gb->eiPending <= 0) {
251 gb->memory.ime = true;
252 GBUpdateIRQs(gb);
253 gb->eiPending = 0;
254 }
255 }
256
257 testEvent = GBVideoProcessEvents(&gb->video, cycles >> gb->doubleSpeed);
258 if (testEvent != INT_MAX) {
259 testEvent <<= gb->doubleSpeed;
260 if (testEvent < nextEvent) {
261 nextEvent = testEvent;
262 }
263 }
264
265 testEvent = GBAudioProcessEvents(&gb->audio, cycles >> gb->doubleSpeed);
266 if (testEvent != INT_MAX) {
267 testEvent <<= gb->doubleSpeed;
268 if (testEvent < nextEvent) {
269 nextEvent = testEvent;
270 }
271 }
272
273 testEvent = GBTimerProcessEvents(&gb->timer, cycles);
274 if (testEvent < nextEvent) {
275 nextEvent = testEvent;
276 }
277
278 testEvent = GBMemoryProcessEvents(gb, cycles);
279 if (testEvent < nextEvent) {
280 nextEvent = testEvent;
281 }
282
283 cpu->cycles -= cycles;
284 cpu->nextEvent = nextEvent;
285
286 if (cpu->halted) {
287 cpu->cycles = cpu->nextEvent;
288 }
289 } while (cpu->cycles >= cpu->nextEvent);
290}
291
292void GBSetInterrupts(struct LR35902Core* cpu, bool enable) {
293 struct GB* gb = (struct GB*) cpu->master;
294 if (!enable) {
295 gb->memory.ime = enable;
296 gb->eiPending = 0;
297 GBUpdateIRQs(gb);
298 } else {
299 if (cpu->nextEvent > cpu->cycles + 4) {
300 cpu->nextEvent = cpu->cycles + 4;
301 }
302 gb->eiPending = cpu->cycles + 4;
303 }
304}
305
306void GBHalt(struct LR35902Core* cpu) {
307 cpu->cycles = cpu->nextEvent;
308 cpu->halted = true;
309}
310
311void GBStop(struct LR35902Core* cpu) {
312 struct GB* gb = (struct GB*) cpu->master;
313 if (gb->memory.io[REG_KEY1] & 1) {
314 gb->doubleSpeed ^= 1;
315 gb->memory.io[REG_KEY1] &= 1;
316 gb->memory.io[REG_KEY1] |= gb->doubleSpeed << 7;
317 }
318 // TODO: Actually stop
319}
320
321void GBIllegal(struct LR35902Core* cpu) {
322 // TODO
323 mLOG(GB, GAME_ERROR, "Hit illegal opcode at address %04X:%02X\n", cpu->pc, cpu->bus);
324}
325
326bool GBIsROM(struct VFile* vf) {
327 vf->seek(vf, 0x104, SEEK_SET);
328 uint8_t header[4];
329 static const uint8_t knownHeader[4] = { 0xCE, 0xED, 0x66, 0x66};
330
331 if (vf->read(vf, &header, sizeof(header)) < (ssize_t) sizeof(header)) {
332 return false;
333 }
334 if (memcmp(header, knownHeader, sizeof(header))) {
335 return false;
336 }
337 return true;
338}
339
340void GBGetGameTitle(struct GB* gb, char* out) {
341 const struct GBCartridge* cart = NULL;
342 if (gb->memory.rom) {
343 cart = (const struct GBCartridge*) &gb->memory.rom[0x100];
344 }
345 if (gb->pristineRom) {
346 cart = (const struct GBCartridge*) &gb->pristineRom[0x100];
347 }
348 if (!cart) {
349 return;
350 }
351 if (cart->oldLicensee != 0x33) {
352 memcpy(out, cart->titleLong, 16);
353 } else {
354 memcpy(out, cart->titleShort, 11);
355 }
356}
357
358void GBGetGameCode(struct GB* gb, char* out) {
359 memset(out, 0, 4);
360 const struct GBCartridge* cart = NULL;
361 if (gb->memory.rom) {
362 cart = (const struct GBCartridge*) &gb->memory.rom[0x100];
363 }
364 if (gb->pristineRom) {
365 cart = (const struct GBCartridge*) &gb->pristineRom[0x100];
366 }
367 if (!cart) {
368 return;
369 }
370 if (cart->oldLicensee == 0x33) {
371 memcpy(out, cart->maker, 11);
372 }
373}