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}
66
67bool GBLoadROM(struct GB* gb, struct VFile* vf) {
68 GBUnloadROM(gb);
69 gb->romVf = vf;
70 gb->pristineRomSize = vf->size(vf);
71 vf->seek(vf, 0, SEEK_SET);
72#ifdef _3DS
73 gb->pristineRom = 0;
74 if (gb->pristineRomSize <= romBufferSize) {
75 gb->pristineRom = romBuffer;
76 vf->read(vf, romBuffer, gb->pristineRomSize);
77 }
78#else
79 gb->pristineRom = vf->map(vf, gb->pristineRomSize, MAP_READ);
80#endif
81 if (!gb->pristineRom) {
82 return false;
83 }
84 gb->yankedRomSize = 0;
85 gb->memory.rom = gb->pristineRom;
86 gb->memory.romSize = gb->pristineRomSize;
87 gb->romCrc32 = doCrc32(gb->memory.rom, gb->memory.romSize);
88
89 // TODO: error check
90 return true;
91}
92
93bool GBLoadSave(struct GB* gb, struct VFile* vf) {
94 gb->sramVf = vf;
95 if (vf) {
96 // TODO: Do this in bank-switching code
97 if (vf->size(vf) < 0x20000) {
98 vf->truncate(vf, 0x20000);
99 }
100 gb->memory.sram = vf->map(vf, 0x20000, MAP_WRITE);
101 } else {
102 gb->memory.sram = anonymousMemoryMap(0x20000);
103 }
104 return gb->memory.sram;
105}
106
107void GBUnloadROM(struct GB* gb) {
108 // TODO: Share with GBAUnloadROM
109 if (gb->memory.rom && gb->pristineRom != gb->memory.rom) {
110 if (gb->yankedRomSize) {
111 gb->yankedRomSize = 0;
112 }
113 mappedMemoryFree(gb->memory.rom, 0x400000);
114 }
115 gb->memory.rom = 0;
116
117 if (gb->romVf) {
118#ifndef _3DS
119 gb->romVf->unmap(gb->romVf, gb->pristineRom, gb->pristineRomSize);
120#endif
121 gb->pristineRom = 0;
122 gb->romVf = 0;
123 }
124
125 if (gb->sramVf) {
126 gb->sramVf->unmap(gb->sramVf, gb->memory.sram, 0x8000);
127 gb->sramVf = 0;
128 } else if (gb->memory.sram) {
129 mappedMemoryFree(gb->memory.sram, 0x8000);
130 }
131 gb->memory.sram = 0;
132}
133
134void GBApplyPatch(struct GB* gb, struct Patch* patch) {
135 size_t patchedSize = patch->outputSize(patch, gb->memory.romSize);
136 if (!patchedSize) {
137 return;
138 }
139 if (patchedSize > 0x400000) {
140 patchedSize = 0x400000;
141 }
142 gb->memory.rom = anonymousMemoryMap(0x400000);
143 if (!patch->applyPatch(patch, gb->pristineRom, gb->pristineRomSize, gb->memory.rom, patchedSize)) {
144 mappedMemoryFree(gb->memory.rom, patchedSize);
145 gb->memory.rom = gb->pristineRom;
146 return;
147 }
148 gb->memory.romSize = patchedSize;
149 gb->romCrc32 = doCrc32(gb->memory.rom, gb->memory.romSize);
150}
151
152void GBDestroy(struct GB* gb) {
153 GBUnloadROM(gb);
154
155 GBMemoryDeinit(gb);
156}
157
158void GBInterruptHandlerInit(struct LR35902InterruptHandler* irqh) {
159 irqh->reset = GBReset;
160 irqh->processEvents = GBProcessEvents;
161 irqh->setInterrupts = GBSetInterrupts;
162 irqh->hitIllegal = GBIllegal;
163 irqh->hitStub = GBHitStub;
164 irqh->halt = GBHalt;
165}
166
167void GBReset(struct LR35902Core* cpu) {
168 cpu->a = 1;
169 cpu->f.packed = 0xB0;
170 cpu->b = 0;
171 cpu->c = 0x13;
172 cpu->d = 0;
173 cpu->e = 0xD8;
174 cpu->h = 1;
175 cpu->l = 0x4D;
176 cpu->sp = 0xFFFE;
177 cpu->pc = 0x100;
178
179 struct GB* gb = (struct GB*) cpu->master;
180
181 if (gb->yankedRomSize) {
182 gb->memory.romSize = gb->yankedRomSize;
183 gb->yankedRomSize = 0;
184 }
185 GBMemoryReset(gb);
186 GBVideoReset(&gb->video);
187 GBTimerReset(&gb->timer);
188 GBIOReset(gb);
189 GBAudioReset(&gb->audio);
190}
191
192void GBUpdateIRQs(struct GB* gb) {
193 int irqs = gb->memory.ie & gb->memory.io[REG_IF];
194 if (!irqs) {
195 return;
196 }
197 gb->cpu->halted = false;
198
199 if (!gb->memory.ime) {
200 return;
201 }
202
203 if (irqs & (1 << GB_IRQ_VBLANK)) {
204 LR35902RaiseIRQ(gb->cpu, GB_VECTOR_VBLANK);
205 gb->memory.io[REG_IF] &= ~(1 << GB_IRQ_VBLANK);
206 return;
207 }
208 if (irqs & (1 << GB_IRQ_LCDSTAT)) {
209 LR35902RaiseIRQ(gb->cpu, GB_VECTOR_LCDSTAT);
210 gb->memory.io[REG_IF] &= ~(1 << GB_IRQ_LCDSTAT);
211 return;
212 }
213 if (irqs & (1 << GB_IRQ_TIMER)) {
214 LR35902RaiseIRQ(gb->cpu, GB_VECTOR_TIMER);
215 gb->memory.io[REG_IF] &= ~(1 << GB_IRQ_TIMER);
216 return;
217 }
218 if (irqs & (1 << GB_IRQ_SIO)) {
219 LR35902RaiseIRQ(gb->cpu, GB_VECTOR_SIO);
220 gb->memory.io[REG_IF] &= ~(1 << GB_IRQ_SIO);
221 return;
222 }
223 if (irqs & (1 << GB_IRQ_KEYPAD)) {
224 LR35902RaiseIRQ(gb->cpu, GB_VECTOR_KEYPAD);
225 gb->memory.io[REG_IF] &= ~(1 << GB_IRQ_KEYPAD);
226 }
227}
228
229void GBProcessEvents(struct LR35902Core* cpu) {
230 struct GB* gb = (struct GB*) cpu->master;
231 do {
232 int32_t cycles = cpu->nextEvent;
233 int32_t nextEvent = INT_MAX;
234 int32_t testEvent;
235
236 if (gb->eiPending) {
237 gb->eiPending -= cycles;
238 if (gb->eiPending <= 0) {
239 gb->memory.ime = true;
240 GBUpdateIRQs(gb);
241 gb->eiPending = 0;
242 }
243 }
244
245 testEvent = GBVideoProcessEvents(&gb->video, cycles);
246 if (testEvent < nextEvent) {
247 nextEvent = testEvent;
248 }
249
250 testEvent = GBAudioProcessEvents(&gb->audio, cycles);
251 if (testEvent < nextEvent) {
252 nextEvent = testEvent;
253 }
254
255 testEvent = GBTimerProcessEvents(&gb->timer, cycles);
256 if (testEvent < nextEvent) {
257 nextEvent = testEvent;
258 }
259
260 testEvent = GBMemoryProcessEvents(gb, cycles);
261 if (testEvent < nextEvent) {
262 nextEvent = testEvent;
263 }
264
265 cpu->cycles -= cycles;
266 cpu->nextEvent = nextEvent;
267
268 if (cpu->halted) {
269 cpu->cycles = cpu->nextEvent;
270 }
271 } while (cpu->cycles >= cpu->nextEvent);
272}
273
274void GBSetInterrupts(struct LR35902Core* cpu, bool enable) {
275 struct GB* gb = (struct GB*) cpu->master;
276 if (!enable) {
277 gb->memory.ime = enable;
278 gb->eiPending = 0;
279 GBUpdateIRQs(gb);
280 } else {
281 if (cpu->nextEvent > cpu->cycles + 4) {
282 cpu->nextEvent = cpu->cycles + 4;
283 }
284 gb->eiPending = cpu->cycles + 4;
285 }
286}
287
288void GBHalt(struct LR35902Core* cpu) {
289 cpu->cycles = cpu->nextEvent;
290 cpu->halted = true;
291}
292
293void GBIllegal(struct LR35902Core* cpu) {
294 // TODO
295 mLOG(GB, GAME_ERROR, "Hit illegal opcode at address %04X:%02X\n", cpu->pc, cpu->bus);
296}
297
298void GBHitStub(struct LR35902Core* cpu) {
299 // TODO
300 mLOG(GB, STUB, "Hit stub at address %04X:%02X\n", cpu->pc, cpu->bus);
301}
302
303bool GBIsROM(struct VFile* vf) {
304 vf->seek(vf, 0x104, SEEK_SET);
305 uint8_t header[4];
306 static const uint8_t knownHeader[4] = { 0xCE, 0xED, 0x66, 0x66};
307
308 if (vf->read(vf, &header, sizeof(header)) < (ssize_t) sizeof(header)) {
309 return false;
310 }
311 if (memcmp(header, knownHeader, sizeof(header))) {
312 return false;
313 }
314 return true;
315}
316
317void GBGetGameTitle(struct GB* gb, char* out) {
318 const struct GBCartridge* cart = NULL;
319 if (gb->memory.rom) {
320 cart = (const struct GBCartridge*) &gb->memory.rom[0x100];
321 }
322 if (gb->pristineRom) {
323 cart = (const struct GBCartridge*) &gb->pristineRom[0x100];
324 }
325 if (!cart) {
326 return;
327 }
328 if (cart->oldLicensee != 0x33) {
329 memcpy(out, cart->titleLong, 16);
330 } else {
331 memcpy(out, cart->titleShort, 11);
332 }
333}