src/gba/gba.c (view raw)
1#include "gba.h"
2
3#include "gba-bios.h"
4#include "gba-io.h"
5
6#include "debugger.h"
7
8#include <limits.h>
9#include <stdarg.h>
10#include <stdio.h>
11#include <stdlib.h>
12#include <string.h>
13#include <sys/mman.h>
14#include <sys/stat.h>
15
16enum {
17 SP_BASE_SYSTEM = 0x03FFFF00,
18 SP_BASE_IRQ = 0x03FFFFA0,
19 SP_BASE_SUPERVISOR = 0x03FFFFE0
20};
21
22static void GBAProcessEvents(struct ARMBoard* board);
23static int32_t GBATimersProcessEvents(struct GBA* gba, int32_t cycles);
24static void GBAHitStub(struct ARMBoard* board, uint32_t opcode);
25
26void GBAInit(struct GBA* gba) {
27 gba->errno = GBA_NO_ERROR;
28 gba->errstr = 0;
29
30 ARMInit(&gba->cpu);
31
32 gba->memory.p = gba;
33 GBAMemoryInit(&gba->memory);
34 ARMAssociateMemory(&gba->cpu, &gba->memory.d);
35
36 gba->board.p = gba;
37 GBABoardInit(&gba->board);
38 ARMAssociateBoard(&gba->cpu, &gba->board.d);
39
40 gba->video.p = gba;
41 GBAVideoInit(&gba->video);
42
43 GBAIOInit(gba);
44
45 memset(gba->timers, 0, sizeof(gba->timers));
46
47 gba->springIRQ = 0;
48 gba->keySource = 0;
49
50 ARMReset(&gba->cpu);
51}
52
53void GBADeinit(struct GBA* gba) {
54 GBAMemoryDeinit(&gba->memory);
55}
56
57void GBABoardInit(struct GBABoard* board) {
58 board->d.reset = GBABoardReset;
59 board->d.processEvents = GBAProcessEvents;
60 board->d.swi16 = GBASwi16;
61 board->d.swi32 = GBASwi32;
62 board->d.hitStub = GBAHitStub;
63}
64
65void GBABoardReset(struct ARMBoard* board) {
66 struct ARMCore* cpu = board->cpu;
67 ARMSetPrivilegeMode(cpu, MODE_IRQ);
68 cpu->gprs[ARM_SP] = SP_BASE_IRQ;
69 ARMSetPrivilegeMode(cpu, MODE_SUPERVISOR);
70 cpu->gprs[ARM_SP] = SP_BASE_SUPERVISOR;
71 ARMSetPrivilegeMode(cpu, MODE_SYSTEM);
72 cpu->gprs[ARM_SP] = SP_BASE_SYSTEM;
73}
74
75static void GBAProcessEvents(struct ARMBoard* board) {
76 struct GBABoard* gbaBoard = (struct GBABoard*) board;
77 int32_t cycles = board->cpu->cycles;
78 int32_t nextEvent = INT_MAX;
79 int32_t testEvent;
80
81 if (gbaBoard->p->springIRQ) {
82 ARMRaiseIRQ(&gbaBoard->p->cpu);
83 gbaBoard->p->springIRQ = 0;
84 }
85
86 testEvent = GBAVideoProcessEvents(&gbaBoard->p->video, cycles);
87 if (testEvent < nextEvent) {
88 nextEvent = testEvent;
89 }
90
91 testEvent = GBAMemoryProcessEvents(&gbaBoard->p->memory, cycles);
92 if (testEvent < nextEvent) {
93 nextEvent = testEvent;
94 }
95
96 testEvent = GBATimersProcessEvents(gbaBoard->p, cycles);
97 if (testEvent < nextEvent) {
98 nextEvent = testEvent;
99 }
100
101 board->cpu->cycles = 0;
102 board->cpu->nextEvent = nextEvent;
103}
104
105static int32_t GBATimersProcessEvents(struct GBA* gba, int32_t cycles) {
106 int32_t nextEvent = INT_MAX;
107 if (gba->timersEnabled) {
108 struct GBATimer* timer;
109 struct GBATimer* nextTimer;
110
111 timer = &gba->timers[0];
112 if (timer->enable) {
113 timer->nextEvent -= cycles;
114 timer->lastEvent -= cycles;
115 if (timer->nextEvent <= 0) {
116 timer->lastEvent = timer->nextEvent;
117 timer->nextEvent += timer->overflowInterval;
118 gba->memory.io[REG_TM0CNT_LO >> 1] = timer->reload;
119 timer->oldReload = timer->reload;
120
121 if (timer->doIrq) {
122 GBARaiseIRQ(gba, IRQ_TIMER0);
123 }
124
125 nextTimer = &gba->timers[1];
126 if (nextTimer->countUp) {
127 ++gba->memory.io[REG_TM1CNT_LO >> 1];
128 if (!gba->memory.io[REG_TM1CNT_LO >> 1]) {
129 nextTimer->nextEvent = 0;
130 }
131 }
132 }
133 nextEvent = timer->nextEvent;
134 }
135
136 timer = &gba->timers[1];
137 if (timer->enable) {
138 timer->nextEvent -= cycles;
139 timer->lastEvent -= cycles;
140 if (timer->nextEvent <= 0) {
141 timer->lastEvent = timer->nextEvent;
142 timer->nextEvent += timer->overflowInterval;
143 gba->memory.io[REG_TM1CNT_LO >> 1] = timer->reload;
144 timer->oldReload = timer->reload;
145
146 if (timer->doIrq) {
147 GBARaiseIRQ(gba, IRQ_TIMER1);
148 }
149
150 if (timer->countUp) {
151 timer->nextEvent = INT_MAX;
152 }
153
154 nextTimer = &gba->timers[2];
155 if (nextTimer->countUp) {
156 ++gba->memory.io[REG_TM2CNT_LO >> 1];
157 if (!gba->memory.io[REG_TM2CNT_LO >> 1]) {
158 nextTimer->nextEvent = 0;
159 }
160 }
161 }
162 if (timer->nextEvent < nextEvent) {
163 nextEvent = timer->nextEvent;
164 }
165 }
166
167 timer = &gba->timers[2];
168 if (timer->enable) {
169 timer->nextEvent -= cycles;
170 timer->lastEvent -= cycles;
171 nextEvent = timer->nextEvent;
172 if (timer->nextEvent <= 0) {
173 timer->lastEvent = timer->nextEvent;
174 timer->nextEvent += timer->overflowInterval;
175 gba->memory.io[REG_TM2CNT_LO >> 1] = timer->reload;
176 timer->oldReload = timer->reload;
177
178 if (timer->doIrq) {
179 GBARaiseIRQ(gba, IRQ_TIMER2);
180 }
181
182 if (timer->countUp) {
183 timer->nextEvent = INT_MAX;
184 }
185
186 nextTimer = &gba->timers[3];
187 if (nextTimer->countUp) {
188 ++gba->memory.io[REG_TM3CNT_LO >> 1];
189 if (!gba->memory.io[REG_TM3CNT_LO >> 1]) {
190 nextTimer->nextEvent = 0;
191 }
192 }
193 }
194 if (timer->nextEvent < nextEvent) {
195 nextEvent = timer->nextEvent;
196 }
197 }
198
199 timer = &gba->timers[3];
200 if (timer->enable) {
201 timer->nextEvent -= cycles;
202 timer->lastEvent -= cycles;
203 nextEvent = timer->nextEvent;
204 if (timer->nextEvent <= 0) {
205 timer->lastEvent = timer->nextEvent;
206 timer->nextEvent += timer->overflowInterval;
207 gba->memory.io[REG_TM3CNT_LO >> 1] = timer->reload;
208 timer->oldReload = timer->reload;
209
210 if (timer->doIrq) {
211 GBARaiseIRQ(gba, IRQ_TIMER3);
212 }
213
214 if (timer->countUp) {
215 timer->nextEvent = INT_MAX;
216 }
217 }
218 if (timer->nextEvent < nextEvent) {
219 nextEvent = timer->nextEvent;
220 }
221 }
222 }
223 return nextEvent;
224}
225
226void GBAAttachDebugger(struct GBA* gba, struct ARMDebugger* debugger) {
227 ARMDebuggerInit(debugger, &gba->cpu);
228 gba->debugger = debugger;
229}
230
231void GBALoadROM(struct GBA* gba, int fd) {
232 struct stat info;
233 gba->memory.rom = mmap(0, SIZE_CART0, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
234 fstat(fd, &info);
235 gba->memory.romSize = info.st_size;
236 // TODO: error check
237}
238
239void GBATimerUpdateRegister(struct GBA* gba, int timer) {
240 struct GBATimer* currentTimer = &gba->timers[timer];
241 if (currentTimer->enable && !currentTimer->countUp) {
242 gba->memory.io[(REG_TM0CNT_LO + (timer << 2)) >> 1] = currentTimer->oldReload + ((gba->cpu.cycles - currentTimer->lastEvent) >> currentTimer->prescaleBits);
243 }
244}
245
246void GBATimerWriteTMCNT_LO(struct GBA* gba, int timer, uint16_t reload) {
247 gba->timers[timer].reload = reload;
248}
249
250void GBATimerWriteTMCNT_HI(struct GBA* gba, int timer, uint16_t control) {
251 struct GBATimer* currentTimer = &gba->timers[timer];
252 GBATimerUpdateRegister(gba, timer);
253
254 int oldPrescale = currentTimer->prescaleBits;
255 switch (control & 0x0003) {
256 case 0x0000:
257 currentTimer->prescaleBits = 0;
258 break;
259 case 0x0001:
260 currentTimer->prescaleBits = 6;
261 break;
262 case 0x0002:
263 currentTimer->prescaleBits = 8;
264 break;
265 case 0x0003:
266 currentTimer->prescaleBits = 10;
267 break;
268 }
269 currentTimer->countUp = !!(control & 0x0004);
270 currentTimer->doIrq = !!(control & 0x0040);
271 currentTimer->overflowInterval = (0x10000 - currentTimer->reload) << currentTimer->prescaleBits;
272 int wasEnabled = currentTimer->enable;
273 currentTimer->enable = !!(control & 0x0080);
274 if (!wasEnabled && currentTimer->enable) {
275 if (!currentTimer->countUp) {
276 currentTimer->nextEvent = gba->cpu.cycles + currentTimer->overflowInterval;
277 } else {
278 currentTimer->nextEvent = INT_MAX;
279 }
280 gba->memory.io[(REG_TM0CNT_LO + (timer << 2)) >> 1] = currentTimer->reload;
281 currentTimer->oldReload = currentTimer->reload;
282 gba->timersEnabled |= 1 << timer;
283 } else if (wasEnabled && !currentTimer->enable) {
284 if (!currentTimer->countUp) {
285 gba->memory.io[(REG_TM0CNT_LO + (timer << 2)) >> 1] = currentTimer->oldReload + ((gba->cpu.cycles - currentTimer->lastEvent) >> oldPrescale);
286 }
287 gba->timersEnabled &= ~(1 << timer);
288 } else if (currentTimer->prescaleBits != oldPrescale && !currentTimer->countUp) {
289 // FIXME: this might be before present
290 currentTimer->nextEvent = currentTimer->lastEvent + currentTimer->overflowInterval;
291 }
292
293 if (currentTimer->nextEvent < gba->cpu.nextEvent) {
294 gba->cpu.nextEvent = currentTimer->nextEvent;
295 }
296};
297
298void GBAWriteIE(struct GBA* gba, uint16_t value) {
299 if (value & (1 << IRQ_SIO)) {
300 GBALog(GBA_LOG_STUB, "SIO interrupts not implemented");
301 }
302
303 if (value & (1 << IRQ_KEYPAD)) {
304 GBALog(GBA_LOG_STUB, "Keypad interrupts not implemented");
305 }
306
307 if (value & (1 << IRQ_GAMEPAK)) {
308 GBALog(GBA_LOG_STUB, "Gamepak interrupts not implemented");
309 }
310
311 if (gba->memory.io[REG_IME >> 1] && value & gba->memory.io[REG_IF >> 1]) {
312 ARMRaiseIRQ(&gba->cpu);
313 }
314}
315
316void GBAWriteIME(struct GBA* gba, uint16_t value) {
317 if (value && gba->memory.io[REG_IE >> 1] & gba->memory.io[REG_IF >> 1]) {
318 ARMRaiseIRQ(&gba->cpu);
319 }
320}
321
322void GBARaiseIRQ(struct GBA* gba, enum GBAIRQ irq) {
323 gba->memory.io[REG_IF >> 1] |= 1 << irq;
324
325 if (gba->memory.io[REG_IME >> 1] && (gba->memory.io[REG_IE >> 1] & 1 << irq)) {
326 ARMRaiseIRQ(&gba->cpu);
327 }
328}
329
330int GBATestIRQ(struct GBA* gba) {
331 if (gba->memory.io[REG_IME >> 1] && gba->memory.io[REG_IE >> 1] & gba->memory.io[REG_IF >> 1]) {
332 gba->springIRQ = 1;
333 gba->cpu.nextEvent = gba->cpu.cycles;
334 return 1;
335 }
336 return 0;
337}
338
339int GBAWaitForIRQ(struct GBA* gba) {
340 while (1) {
341 if (gba->cpu.nextEvent == INT_MAX) {
342 return 0;
343 } else {
344 gba->cpu.cycles = gba->cpu.nextEvent;
345 GBAProcessEvents(&gba->board.d);
346 if (gba->memory.io[REG_IF >> 1]) {
347 return 1;
348 }
349 }
350 }
351}
352
353int GBAHalt(struct GBA* gba) {
354 return GBAWaitForIRQ(gba);
355}
356
357void GBALog(int level, const char* format, ...) {
358 (void)(level);
359 va_list args;
360 va_start(args, format);
361 vprintf(format, args);
362 va_end(args);
363 printf("\n");
364}
365
366void GBAHitStub(struct ARMBoard* board, uint32_t opcode) {
367 GBALog(GBA_LOG_STUB, "Stub opcode: %08x", opcode);
368 struct GBABoard* gbaBoard = (struct GBABoard*) board;
369 if (!gbaBoard->p->debugger) {
370 abort();
371 } else {
372 ARMDebuggerEnter(gbaBoard->p->debugger);
373 }
374}