src/gba/dma.c (view raw)
1/* Copyright (c) 2013-2015 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 <mgba/internal/gba/dma.h>
7
8#include <mgba/internal/gba/gba.h>
9#include <mgba/internal/gba/io.h>
10
11static void _dmaEvent(struct mTiming* timing, void* context, uint32_t cyclesLate);
12
13static void GBADMAService(struct GBA* gba, int number, struct GBADMA* info);
14
15static const int DMA_OFFSET[] = { 1, -1, 0, 1 };
16
17void GBADMAInit(struct GBA* gba) {
18 gba->memory.dmaEvent.name = "GBA DMA";
19 gba->memory.dmaEvent.callback = _dmaEvent;
20 gba->memory.dmaEvent.context = gba;
21 gba->memory.dmaEvent.priority = 0x40;
22}
23
24void GBADMAReset(struct GBA* gba) {
25 memset(gba->memory.dma, 0, sizeof(gba->memory.dma));
26 int i;
27 for (i = 0; i < 4; ++i) {
28 gba->memory.dma[i].count = 0x4000;
29 }
30 gba->memory.dma[3].count = 0x10000;
31 gba->memory.activeDMA = -1;
32}
33static bool _isValidDMASAD(int dma, uint32_t address) {
34 if (dma == 0 && address >= BASE_CART0 && address < BASE_CART_SRAM) {
35 return false;
36 }
37 return address >= BASE_WORKING_RAM;
38}
39
40static bool _isValidDMADAD(int dma, uint32_t address) {
41 return dma == 3 || address < BASE_CART0;
42}
43
44uint32_t GBADMAWriteSAD(struct GBA* gba, int dma, uint32_t address) {
45 struct GBAMemory* memory = &gba->memory;
46 address &= 0x0FFFFFFE;
47 if (_isValidDMASAD(dma, address)) {
48 memory->dma[dma].source = address;
49 }
50 return memory->dma[dma].source;
51}
52
53uint32_t GBADMAWriteDAD(struct GBA* gba, int dma, uint32_t address) {
54 struct GBAMemory* memory = &gba->memory;
55 address &= 0x0FFFFFFE;
56 if (_isValidDMADAD(dma, address)) {
57 memory->dma[dma].dest = address;
58 }
59 return memory->dma[dma].dest;
60}
61
62void GBADMAWriteCNT_LO(struct GBA* gba, int dma, uint16_t count) {
63 struct GBAMemory* memory = &gba->memory;
64 memory->dma[dma].count = count ? count : (dma == 3 ? 0x10000 : 0x4000);
65}
66
67uint16_t GBADMAWriteCNT_HI(struct GBA* gba, int dma, uint16_t control) {
68 struct GBAMemory* memory = &gba->memory;
69 struct GBADMA* currentDma = &memory->dma[dma];
70 int wasEnabled = GBADMARegisterIsEnable(currentDma->reg);
71 if (dma < 3) {
72 control &= 0xF7E0;
73 } else {
74 control &= 0xFFE0;
75 }
76 currentDma->reg = control;
77
78 if (GBADMARegisterIsDRQ(currentDma->reg)) {
79 mLOG(GBA_MEM, STUB, "DRQ not implemented");
80 }
81
82 if (!wasEnabled && GBADMARegisterIsEnable(currentDma->reg)) {
83 currentDma->nextSource = currentDma->source;
84 currentDma->nextDest = currentDma->dest;
85 GBADMASchedule(gba, dma, currentDma);
86 }
87 // If the DMA has already occurred, this value might have changed since the function started
88 return currentDma->reg;
89};
90
91void GBADMASchedule(struct GBA* gba, int number, struct GBADMA* info) {
92 switch (GBADMARegisterGetTiming(info->reg)) {
93 case DMA_TIMING_NOW:
94 info->when = mTimingCurrentTime(&gba->timing) + 3; // DMAs take 3 cycles to start
95 info->nextCount = info->count;
96 break;
97 case DMA_TIMING_HBLANK:
98 case DMA_TIMING_VBLANK:
99 // Handled implicitly
100 return;
101 case DMA_TIMING_CUSTOM:
102 switch (number) {
103 case 0:
104 mLOG(GBA_MEM, WARN, "Discarding invalid DMA0 scheduling");
105 return;
106 case 1:
107 case 2:
108 GBAAudioScheduleFifoDma(&gba->audio, number, info);
109 break;
110 case 3:
111 // GBAVideoScheduleVCaptureDma(dma, info);
112 break;
113 }
114 }
115 GBADMAUpdate(gba);
116}
117
118void GBADMARunHblank(struct GBA* gba, int32_t cycles) {
119 struct GBAMemory* memory = &gba->memory;
120 struct GBADMA* dma;
121 int i;
122 for (i = 0; i < 4; ++i) {
123 dma = &memory->dma[i];
124 if (GBADMARegisterIsEnable(dma->reg) && GBADMARegisterGetTiming(dma->reg) == DMA_TIMING_HBLANK && !dma->nextCount) {
125 dma->when = mTimingCurrentTime(&gba->timing) + 3 + cycles;
126 dma->nextCount = dma->count;
127 }
128 }
129 GBADMAUpdate(gba);
130}
131
132void GBADMARunVblank(struct GBA* gba, int32_t cycles) {
133 struct GBAMemory* memory = &gba->memory;
134 struct GBADMA* dma;
135 int i;
136 for (i = 0; i < 4; ++i) {
137 dma = &memory->dma[i];
138 if (GBADMARegisterIsEnable(dma->reg) && GBADMARegisterGetTiming(dma->reg) == DMA_TIMING_VBLANK && !dma->nextCount) {
139 dma->when = mTimingCurrentTime(&gba->timing) + 3 + cycles;
140 dma->nextCount = dma->count;
141 }
142 }
143 GBADMAUpdate(gba);
144}
145
146void _dmaEvent(struct mTiming* timing, void* context, uint32_t cyclesLate) {
147 UNUSED(timing);
148 UNUSED(cyclesLate);
149 struct GBA* gba = context;
150 struct GBAMemory* memory = &gba->memory;
151 struct GBADMA* dma = &memory->dma[memory->activeDMA];
152 if (dma->nextCount == dma->count) {
153 dma->when = mTimingCurrentTime(&gba->timing);
154 }
155 if (dma->nextCount & 0xFFFFF) {
156 GBADMAService(gba, memory->activeDMA, dma);
157 } else {
158 dma->nextCount = 0;
159 if (!GBADMARegisterIsRepeat(dma->reg) || GBADMARegisterGetTiming(dma->reg) == DMA_TIMING_NOW) {
160 dma->reg = GBADMARegisterClearEnable(dma->reg);
161
162 // Clear the enable bit in memory
163 memory->io[(REG_DMA0CNT_HI + memory->activeDMA * (REG_DMA1CNT_HI - REG_DMA0CNT_HI)) >> 1] &= 0x7FE0;
164 }
165 if (GBADMARegisterGetDestControl(dma->reg) == DMA_INCREMENT_RELOAD) {
166 dma->nextDest = dma->dest;
167 }
168 if (GBADMARegisterIsDoIRQ(dma->reg)) {
169 GBARaiseIRQ(gba, IRQ_DMA0 + memory->activeDMA);
170 }
171 GBADMAUpdate(gba);
172 }
173}
174
175void GBADMAUpdate(struct GBA* gba) {
176 int i;
177 struct GBAMemory* memory = &gba->memory;
178 memory->activeDMA = -1;
179 uint32_t currentTime = mTimingCurrentTime(&gba->timing);
180 for (i = 0; i < 4; ++i) {
181 struct GBADMA* dma = &memory->dma[i];
182 if (GBADMARegisterIsEnable(dma->reg) && dma->nextCount) {
183 memory->activeDMA = i;
184 break;
185 }
186 }
187
188 if (memory->activeDMA >= 0) {
189 mTimingDeschedule(&gba->timing, &memory->dmaEvent);
190 mTimingSchedule(&gba->timing, &memory->dmaEvent, memory->dma[memory->activeDMA].when - currentTime);
191 } else {
192 gba->cpuBlocked = false;
193 }
194}
195
196void GBADMAService(struct GBA* gba, int number, struct GBADMA* info) {
197 struct GBAMemory* memory = &gba->memory;
198 struct ARMCore* cpu = gba->cpu;
199 uint32_t width = 2 << GBADMARegisterGetWidth(info->reg);
200 int32_t wordsRemaining = info->nextCount;
201 uint32_t source = info->nextSource;
202 uint32_t dest = info->nextDest;
203 uint32_t sourceRegion = source >> BASE_OFFSET;
204 uint32_t destRegion = dest >> BASE_OFFSET;
205 int32_t cycles = 2;
206
207 gba->cpuBlocked = true;
208 if (info->count == info->nextCount) {
209 if (sourceRegion < REGION_CART0 || destRegion < REGION_CART0) {
210 cycles += 2;
211 }
212 if (width == 4) {
213 cycles += memory->waitstatesNonseq32[sourceRegion] + memory->waitstatesNonseq32[destRegion];
214 } else {
215 cycles += memory->waitstatesNonseq16[sourceRegion] + memory->waitstatesNonseq16[destRegion];
216 }
217 source &= -width;
218 dest &= -width;
219 } else {
220 if (width == 4) {
221 cycles += memory->waitstatesSeq32[sourceRegion] + memory->waitstatesSeq32[destRegion];
222 } else {
223 cycles += memory->waitstatesSeq16[sourceRegion] + memory->waitstatesSeq16[destRegion];
224 }
225 }
226 info->when += cycles;
227
228 gba->performingDMA = 1 | (number << 1);
229 uint32_t word;
230 if (width == 4) {
231 word = cpu->memory.load32(cpu, source, 0);
232 gba->bus = word;
233 cpu->memory.store32(cpu, dest, word, 0);
234 } else {
235 if (sourceRegion == REGION_CART2_EX && memory->savedata.type == SAVEDATA_EEPROM) {
236 word = GBASavedataReadEEPROM(&memory->savedata);
237 cpu->memory.store16(cpu, dest, word, 0);
238 } else if (destRegion == REGION_CART2_EX) {
239 if (memory->savedata.type == SAVEDATA_AUTODETECT) {
240 mLOG(GBA_MEM, INFO, "Detected EEPROM savegame");
241 GBASavedataInitEEPROM(&memory->savedata, gba->realisticTiming);
242 }
243 word = cpu->memory.load16(cpu, source, 0);
244 GBASavedataWriteEEPROM(&memory->savedata, word, wordsRemaining);
245 } else {
246 word = cpu->memory.load16(cpu, source, 0);
247 cpu->memory.store16(cpu, dest, word, 0);
248 }
249 gba->bus = word | (word << 16);
250 }
251 int sourceOffset = DMA_OFFSET[GBADMARegisterGetSrcControl(info->reg)] * width;
252 int destOffset = DMA_OFFSET[GBADMARegisterGetDestControl(info->reg)] * width;
253 source += sourceOffset;
254 dest += destOffset;
255 --wordsRemaining;
256 gba->performingDMA = 0;
257
258 info->nextCount = wordsRemaining;
259 info->nextSource = source;
260 info->nextDest = dest;
261 if (!wordsRemaining) {
262 info->nextCount |= 0x80000000;
263 }
264 GBADMAUpdate(gba);
265}