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GB MBC: Fix MBC2 saves (fixes #954)

This commit is contained in:
Vicki Pfau 2018-01-08 18:24:29 -08:00
parent 52be25028e
commit a74fe13506
3 changed files with 19 additions and 3 deletions
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1
CHANGES
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@ -13,6 +13,7 @@ Bugfixes:
- GBA Audio: Increase PSG volume (fixes mgba.io/i/932)
- GBA BIOS: Fix incorrect exit condition in LZ77
- 3DS: Fix opening files in directory names with trailing slashes
- GB MBC: Fix MBC2 saves (fixes mgba.io/i/954)
Misc:
- GBA: Improve multiboot image detection
- GB MBC: Remove erroneous bank 0 wrapping

19
src/gb/mbc.c
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@ -30,6 +30,7 @@ static void _GBMBC7(struct GB*, uint16_t address, uint8_t value);
static void _GBHuC3(struct GB*, uint16_t address, uint8_t value);
static void _GBPocketCam(struct GB* gb, uint16_t address, uint8_t value);
static uint8_t _GBMBC2Read(struct GBMemory*, uint16_t address);
static uint8_t _GBMBC7Read(struct GBMemory*, uint16_t address);
static uint8_t _GBPocketCamRead(struct GBMemory*, uint16_t address);
@ -183,7 +184,8 @@ void GBMBCInit(struct GB* gb) {
break;
case GB_MBC2:
gb->memory.mbcWrite = _GBMBC2;
gb->sramSize = 0x200;
gb->memory.mbcRead = _GBMBC2Read;
gb->sramSize = 0x100;
break;
case GB_MBC3:
gb->memory.mbcWrite = _GBMBC3;
@ -355,6 +357,7 @@ void _GBMBC1(struct GB* gb, uint16_t address, uint8_t value) {
void _GBMBC2(struct GB* gb, uint16_t address, uint8_t value) {
struct GBMemory* memory = &gb->memory;
int shift = (address & 1) * 4;
int bank = value & 0xF;
switch (address >> 13) {
case 0x0:
@ -364,7 +367,6 @@ void _GBMBC2(struct GB* gb, uint16_t address, uint8_t value) {
break;
case 0xA:
memory->sramAccess = true;
GBMBCSwitchSramBank(gb, memory->sramCurrentBank);
break;
default:
// TODO
@ -378,6 +380,13 @@ void _GBMBC2(struct GB* gb, uint16_t address, uint8_t value) {
}
GBMBCSwitchBank(gb, bank);
break;
case 0x5:
if (!memory->sramAccess) {
return;
}
address &= 0x1FF;
memory->sramBank[(address >> 1)] &= 0xF0 >> shift;
memory->sramBank[(address >> 1)] |= (value & 0xF) << shift;
default:
// TODO
mLOG(GB_MBC, STUB, "MBC2 unknown address: %04X:%02X", address, value);
@ -385,6 +394,12 @@ void _GBMBC2(struct GB* gb, uint16_t address, uint8_t value) {
}
}
static uint8_t _GBMBC2Read(struct GBMemory* memory, uint16_t address) {
address &= 0x1FF;
int shift = (address & 1) * 4;
return (memory->sramBank[(address >> 1)] >> shift) | 0xF0;
}
void _GBMBC3(struct GB* gb, uint16_t address, uint8_t value) {
struct GBMemory* memory = &gb->memory;
int bank = value & 0x7F;

2
src/gb/memory.c
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@ -289,7 +289,7 @@ void GBStore8(struct LR35902Core* cpu, uint16_t address, int8_t value) {
case GB_REGION_EXTERNAL_RAM + 1:
if (memory->rtcAccess) {
memory->rtcRegs[memory->activeRtcReg] = value;
} else if (memory->sramAccess && memory->sram) {
} else if (memory->sramAccess && memory->sram && memory->mbcType != GB_MBC2) {
memory->sramBank[address & (GB_SIZE_EXTERNAL_RAM - 1)] = value;
} else if (memory->mbcType == GB_MBC7) {
GBMBC7Write(memory, address, value);