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 DMG_LR35902_FREQUENCY = 0x400000;
18const uint32_t CGB_LR35902_FREQUENCY = 0x800000;
19const uint32_t SGB_LR35902_FREQUENCY = 0x418B1E;
20
21const uint32_t GB_COMPONENT_MAGIC = 0x400000;
22
23mLOG_DEFINE_CATEGORY(GB, "GB");
24
25static void GBInit(struct LR35902Core* cpu, struct LR35902Component* component);
26static void GBInterruptHandlerInit(struct LR35902InterruptHandler* irqh);
27static void GBProcessEvents(struct LR35902Core* cpu);
28static void GBSetInterrupts(struct LR35902Core* cpu, bool enable);
29static void GBIllegal(struct LR35902Core* cpu);
30static void GBHitStub(struct LR35902Core* cpu);
31
32void GBCreate(struct GB* gb) {
33 gb->d.id = GB_COMPONENT_MAGIC;
34 gb->d.init = GBInit;
35 gb->d.deinit = 0;
36}
37
38static void GBInit(struct LR35902Core* cpu, struct LR35902Component* component) {
39 struct GB* gb = (struct GB*) component;
40 gb->cpu = cpu;
41
42 GBInterruptHandlerInit(&cpu->irqh);
43 GBMemoryInit(gb);
44
45 gb->video.p = gb;
46 GBVideoInit(&gb->video);
47
48 gb->audio.p = gb;
49 GBAudioInit(&gb->audio, 2048); // TODO: Remove magic constant
50
51 gb->timer.p = gb;
52
53 gb->romVf = 0;
54 gb->sramVf = 0;
55
56 gb->pristineRom = 0;
57 gb->pristineRomSize = 0;
58 gb->yankedRomSize = 0;
59
60 gb->eiPending = false;
61}
62
63bool GBLoadROM(struct GB* gb, struct VFile* vf) {
64 GBUnloadROM(gb);
65 gb->romVf = vf;
66 gb->pristineRomSize = vf->size(vf);
67 vf->seek(vf, 0, SEEK_SET);
68#ifdef _3DS
69 gb->pristineRom = 0;
70 if (gb->pristineRomSize <= romBufferSize) {
71 gb->pristineRom = romBuffer;
72 vf->read(vf, romBuffer, gb->pristineRomSize);
73 }
74#else
75 gb->pristineRom = vf->map(vf, gb->pristineRomSize, MAP_READ);
76#endif
77 if (!gb->pristineRom) {
78 return false;
79 }
80 gb->yankedRomSize = 0;
81 gb->memory.rom = gb->pristineRom;
82 gb->memory.romSize = gb->pristineRomSize;
83 gb->romCrc32 = doCrc32(gb->memory.rom, gb->memory.romSize);
84
85 // TODO: error check
86 return true;
87}
88
89bool GBLoadSave(struct GB* gb, struct VFile* vf) {
90 gb->sramVf = vf;
91 if (vf) {
92 // TODO: Do this in bank-switching code
93 if (vf->size(vf) < 0x20000) {
94 vf->truncate(vf, 0x20000);
95 }
96 gb->memory.sram = vf->map(vf, 0x20000, MAP_WRITE);
97 } else {
98 gb->memory.sram = anonymousMemoryMap(0x20000);
99 }
100 return gb->memory.sram;
101}
102
103void GBUnloadROM(struct GB* gb) {
104 // TODO: Share with GBAUnloadROM
105 if (gb->memory.rom && gb->pristineRom != gb->memory.rom) {
106 if (gb->yankedRomSize) {
107 gb->yankedRomSize = 0;
108 }
109 mappedMemoryFree(gb->memory.rom, 0x400000);
110 }
111 gb->memory.rom = 0;
112
113 if (gb->romVf) {
114#ifndef _3DS
115 gb->romVf->unmap(gb->romVf, gb->pristineRom, gb->pristineRomSize);
116#endif
117 gb->pristineRom = 0;
118 gb->romVf = 0;
119 }
120
121 if (gb->sramVf) {
122 gb->sramVf->unmap(gb->sramVf, gb->memory.sram, 0x8000);
123 } else if (gb->memory.sram) {
124 mappedMemoryFree(gb->memory.sram, 0x8000);
125 }
126 gb->memory.sram = 0;
127}
128
129void GBApplyPatch(struct GB* gb, struct Patch* patch) {
130 size_t patchedSize = patch->outputSize(patch, gb->memory.romSize);
131 if (!patchedSize) {
132 return;
133 }
134 if (patchedSize > 0x400000) {
135 patchedSize = 0x400000;
136 }
137 gb->memory.rom = anonymousMemoryMap(0x400000);
138 if (!patch->applyPatch(patch, gb->pristineRom, gb->pristineRomSize, gb->memory.rom, patchedSize)) {
139 mappedMemoryFree(gb->memory.rom, patchedSize);
140 gb->memory.rom = gb->pristineRom;
141 return;
142 }
143 gb->memory.romSize = patchedSize;
144 gb->romCrc32 = doCrc32(gb->memory.rom, gb->memory.romSize);
145}
146
147void GBDestroy(struct GB* gb) {
148 GBUnloadROM(gb);
149
150 GBMemoryDeinit(gb);
151}
152
153void GBInterruptHandlerInit(struct LR35902InterruptHandler* irqh) {
154 irqh->reset = GBReset;
155 irqh->processEvents = GBProcessEvents;
156 irqh->setInterrupts = GBSetInterrupts;
157 irqh->hitIllegal = GBIllegal;
158 irqh->hitStub = GBHitStub;
159 irqh->halt = GBHalt;
160}
161
162void GBReset(struct LR35902Core* cpu) {
163 cpu->a = 1;
164 cpu->f.packed = 0xB0;
165 cpu->b = 0;
166 cpu->c = 0x13;
167 cpu->d = 0;
168 cpu->e = 0xD8;
169 cpu->h = 1;
170 cpu->l = 0x4D;
171 cpu->sp = 0xFFFE;
172 cpu->pc = 0x100;
173
174 struct GB* gb = (struct GB*) cpu->master;
175
176 if (gb->yankedRomSize) {
177 gb->memory.romSize = gb->yankedRomSize;
178 gb->yankedRomSize = 0;
179 }
180 GBMemoryReset(gb);
181 GBVideoReset(&gb->video);
182 GBTimerReset(&gb->timer);
183 GBIOReset(gb);
184 GBAudioReset(&gb->audio);
185}
186
187void GBUpdateIRQs(struct GB* gb) {
188 int irqs = gb->memory.ie & gb->memory.io[REG_IF];
189 if (!irqs) {
190 return;
191 }
192 gb->cpu->halted = false;
193
194 if (!gb->memory.ime) {
195 return;
196 }
197
198 if (irqs & (1 << GB_IRQ_VBLANK)) {
199 LR35902RaiseIRQ(gb->cpu, GB_VECTOR_VBLANK);
200 gb->memory.io[REG_IF] &= ~(1 << GB_IRQ_VBLANK);
201 return;
202 }
203 if (irqs & (1 << GB_IRQ_LCDSTAT)) {
204 LR35902RaiseIRQ(gb->cpu, GB_VECTOR_LCDSTAT);
205 gb->memory.io[REG_IF] &= ~(1 << GB_IRQ_LCDSTAT);
206 return;
207 }
208 if (irqs & (1 << GB_IRQ_TIMER)) {
209 LR35902RaiseIRQ(gb->cpu, GB_VECTOR_TIMER);
210 gb->memory.io[REG_IF] &= ~(1 << GB_IRQ_TIMER);
211 return;
212 }
213 if (irqs & (1 << GB_IRQ_SIO)) {
214 LR35902RaiseIRQ(gb->cpu, GB_VECTOR_SIO);
215 gb->memory.io[REG_IF] &= ~(1 << GB_IRQ_SIO);
216 return;
217 }
218 if (irqs & (1 << GB_IRQ_KEYPAD)) {
219 LR35902RaiseIRQ(gb->cpu, GB_VECTOR_KEYPAD);
220 gb->memory.io[REG_IF] &= ~(1 << GB_IRQ_KEYPAD);
221 }
222}
223
224void GBProcessEvents(struct LR35902Core* cpu) {
225 struct GB* gb = (struct GB*) cpu->master;
226 do {
227 int32_t cycles = cpu->nextEvent;
228 int32_t nextEvent = INT_MAX;
229 int32_t testEvent;
230
231 if (gb->eiPending) {
232 gb->eiPending -= cycles;
233 if (gb->eiPending <= 0) {
234 gb->memory.ime = true;
235 GBUpdateIRQs(gb);
236 gb->eiPending = 0;
237 }
238 }
239
240 testEvent = GBVideoProcessEvents(&gb->video, cycles);
241 if (testEvent < nextEvent) {
242 nextEvent = testEvent;
243 }
244
245 testEvent = GBAudioProcessEvents(&gb->audio, cycles);
246 if (testEvent < nextEvent) {
247 nextEvent = testEvent;
248 }
249
250 testEvent = GBTimerProcessEvents(&gb->timer, cycles);
251 if (testEvent < nextEvent) {
252 nextEvent = testEvent;
253 }
254
255 testEvent = GBMemoryProcessEvents(gb, cycles);
256 if (testEvent < nextEvent) {
257 nextEvent = testEvent;
258 }
259
260 cpu->cycles -= cycles;
261 cpu->nextEvent = nextEvent;
262
263 if (cpu->halted) {
264 cpu->cycles = cpu->nextEvent;
265 }
266 } while (cpu->cycles >= cpu->nextEvent);
267}
268
269void GBSetInterrupts(struct LR35902Core* cpu, bool enable) {
270 struct GB* gb = (struct GB*) cpu->master;
271 if (!enable) {
272 gb->memory.ime = enable;
273 gb->eiPending = 0;
274 GBUpdateIRQs(gb);
275 } else {
276 if (cpu->nextEvent > cpu->cycles + 4) {
277 cpu->nextEvent = cpu->cycles + 4;
278 }
279 gb->eiPending = cpu->cycles + 4;
280 }
281}
282
283void GBHalt(struct LR35902Core* cpu) {
284 cpu->cycles = cpu->nextEvent;
285 cpu->halted = true;
286}
287
288void GBIllegal(struct LR35902Core* cpu) {
289 // TODO
290 mLOG(GB, GAME_ERROR, "Hit illegal opcode at address %04X:%02X\n", cpu->pc, cpu->bus);
291}
292
293void GBHitStub(struct LR35902Core* cpu) {
294 // TODO
295 mLOG(GB, STUB, "Hit stub at address %04X:%02X\n", cpu->pc, cpu->bus);
296}
297
298bool GBIsROM(struct VFile* vf) {
299 vf->seek(vf, 0x104, SEEK_SET);
300 uint8_t header[4];
301 static const uint8_t knownHeader[4] = { 0xCE, 0xED, 0x66, 0x66};
302
303 if (vf->read(vf, &header, sizeof(header)) < (ssize_t) sizeof(header)) {
304 return false;
305 }
306 if (memcmp(header, knownHeader, sizeof(header))) {
307 return false;
308 }
309 return true;
310}