ShuriZma
/
mgba
mirror of https://github.com/mgba-emu/mgba.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

GB Memory: Implement DMA

This commit is contained in:
Jeffrey Pfau 2016-01-21 19:28:56 -08:00
parent 52adcb68db
commit d2867c26a0
4 changed files with 89 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
src/gb/gb.c
View File

@ -184,6 +184,11 @@ void GBProcessEvents(struct LR35902Core* cpu) {
nextEvent = testEvent;
}
testEvent = GBMemoryProcessEvents(gb, cycles);
if (testEvent < nextEvent) {
nextEvent = testEvent;
}
cpu->cycles -= cycles;
cpu->nextEvent = nextEvent;
}

3
src/gb/io.c
View File

@ -71,6 +71,9 @@ void GBIOWrite(struct GB* gb, unsigned address, uint8_t value) {
value = gb->video.renderer->writeVideoRegister(gb->video.renderer, address, value);
GBVideoWriteLCDC(&gb->video, value);
break;
case REG_DMA:
GBMemoryDMA(gb, value << 8);
break;
case REG_SCY:
case REG_SCX:
case REG_WY:

77
src/gb/memory.c
View File

@ -27,11 +27,12 @@ static void GBSetActiveRegion(struct LR35902Core* cpu, uint16_t address) {
// TODO
}
static void _GBMemoryDMAService(struct GB* gb);
void GBMemoryInit(struct GB* gb) {
struct LR35902Core* cpu = gb->cpu;
cpu->memory.load16 = GBLoad16;
cpu->memory.load8 = GBLoad8;
cpu->memory.store16 = GBStore16;
cpu->memory.store8 = GBStore8;
cpu->memory.setActiveRegion = GBSetActiveRegion;
@ -43,6 +44,9 @@ void GBMemoryInit(struct GB* gb) {
gb->memory.mbcType = GB_MBC_NONE;
gb->memory.mbc = 0;
gb->memory.dmaNext = INT_MAX;
gb->memory.dmaRemaining = 0;
memset(gb->memory.hram, 0, sizeof(gb->memory.hram));
GBIOInit(gb);
@ -115,10 +119,6 @@ void GBMemoryReset(struct GB* gb) {
}
}
uint16_t GBLoad16(struct LR35902Core* cpu, uint16_t address) {
// TODO
}
uint8_t GBLoad8(struct LR35902Core* cpu, uint16_t address) {
struct GB* gb = (struct GB*) cpu->master;
struct GBMemory* memory = &gb->memory;
@ -163,10 +163,6 @@ uint8_t GBLoad8(struct LR35902Core* cpu, uint16_t address) {
}
}
void GBStore16(struct LR35902Core* cpu, uint16_t address, int16_t value) {
// TODO
}
void GBStore8(struct LR35902Core* cpu, uint16_t address, int8_t value) {
struct GB* gb = (struct GB*) cpu->master;
struct GBMemory* memory = &gb->memory;
@ -213,10 +209,67 @@ void GBStore8(struct LR35902Core* cpu, uint16_t address, int8_t value) {
}
}
uint16_t GBView16(struct LR35902Core* cpu, uint16_t address);
int32_t GBMemoryProcessEvents(struct GB* gb, int32_t cycles) {
if (!gb->memory.dmaRemaining) {
return INT_MAX;
}
gb->memory.dmaNext -= cycles;
if (gb->memory.dmaNext <= 0) {
_GBMemoryDMAService(gb);
}
return gb->memory.dmaNext;
}
void GBMemoryDMA(struct GB* gb, uint16_t base) {
if (base > 0xF100) {
return;
}
gb->cpu->memory.store8 = GBDMAStore8;
gb->cpu->memory.load8 = GBDMALoad8;
gb->memory.dmaNext = gb->cpu->cycles + 4;
if (gb->memory.dmaNext < gb->cpu->nextEvent) {
gb->cpu->nextEvent = gb->memory.dmaNext;
}
gb->memory.dmaSource = base;
gb->memory.dmaDest = GB_BASE_OAM;
gb->memory.dmaRemaining = 0xA0;
}
void _GBMemoryDMAService(struct GB* gb) {
uint8_t b = GBLoad8(gb->cpu, gb->memory.dmaSource);
GBStore8(gb->cpu, gb->memory.dmaDest, b);
++gb->memory.dmaSource;
++gb->memory.dmaDest;
--gb->memory.dmaRemaining;
if (gb->memory.dmaRemaining) {
gb->memory.dmaNext += 4;
} else {
gb->memory.dmaNext = INT_MAX;
gb->cpu->memory.store8 = GBStore8;
gb->cpu->memory.load8 = GBLoad8;
}
}
uint8_t GBDMALoad8(struct LR35902Core* cpu, uint16_t address) {
struct GB* gb = (struct GB*) cpu->master;
struct GBMemory* memory = &gb->memory;
if (address < 0xFF80 || address == 0xFFFF) {
return 0xFF;
}
return memory->hram[address & GB_SIZE_HRAM];
}
void GBDMAStore8(struct LR35902Core* cpu, uint16_t address, int8_t value) {
struct GB* gb = (struct GB*) cpu->master;
struct GBMemory* memory = &gb->memory;
if (address < 0xFF80 || address == 0xFFFF) {
return;
}
memory->hram[address & GB_SIZE_HRAM] = value;
}
uint8_t GBView8(struct LR35902Core* cpu, uint16_t address);
void GBPatch16(struct LR35902Core* cpu, uint16_t address, int16_t value, int16_t* old);
void GBPatch8(struct LR35902Core* cpu, uint16_t address, int8_t value, int8_t* old);
static void _switchBank(struct GBMemory* memory, int bank) {

19
src/gb/memory.h
View File

@ -71,12 +71,22 @@ struct GBMemory {
uint8_t* wram;
uint8_t* wramBank;
bool sramAccess;
uint8_t* sram;
uint8_t* sramBank;
int sramCurrentBank;
uint8_t io[GB_SIZE_IO];
bool ime;
uint8_t ie;
uint8_t hram[GB_SIZE_HRAM];
int32_t dmaNext;
uint16_t dmaSource;
uint16_t dmaDest;
int dmaRemaining;
size_t romSize;
};
@ -85,12 +95,15 @@ void GBMemoryDeinit(struct GB* gb);
void GBMemoryReset(struct GB* gb);
uint16_t GBLoad16(struct LR35902Core* cpu, uint16_t address);
uint8_t GBLoad8(struct LR35902Core* cpu, uint16_t address);
void GBStore16(struct LR35902Core* cpu, uint16_t address, int16_t value);
void GBStore8(struct LR35902Core* cpu, uint16_t address, int8_t value);
int32_t GBMemoryProcessEvents(struct GB* gb, int32_t cycles);
void GBMemoryDMA(struct GB* gb, uint16_t base);
uint8_t GBDMALoad8(struct LR35902Core* cpu, uint16_t address);
void GBDMAStore8(struct LR35902Core* cpu, uint16_t address, int8_t value);
uint16_t GBView16(struct LR35902Core* cpu, uint16_t address);
uint8_t GBView8(struct LR35902Core* cpu, uint16_t address);