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Merged
LibretroAdmin merged 3 commits into from
Dec 10, 2025
Merged

Updates1 #132

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613f5be
Refactor GB joypad code
negativeExponent Dec 5, 2025
d6d5d95
libretro: Fix input handling for multiplayer games
negativeExponent Dec 5, 2025
8ba0c5a
Revised gpio/eeprom/backup save checks / logic / range
negativeExponent Dec 10, 2025
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118 changes: 48 additions & 70 deletions src/core/gb/gb.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2207,82 +2207,60 @@ uint8_t gbReadMemory(uint16_t address)

int b = gbMemory[0xff00];

if ((b & 0x30) == 0x20) {
b &= 0xf0;

int joy = 0;
if (gbSgbMode && gbSgbMultiplayer) {
switch (gbSgbNextController) {
case 0x0f:
joy = 0;
break;
case 0x0e:
joy = 1;
break;
case 0x0d:
joy = 2;
break;
case 0x0c:
joy = 3;
break;
default:
joy = 0;
}
}
int joystate = gbJoymask[joy];
if (!(joystate & 128))
b |= 0x08;
if (!(joystate & 64))
b |= 0x04;
if (!(joystate & 32))
b |= 0x02;
if (!(joystate & 16))
b |= 0x01;

gbMemory[0xff00] = (uint8_t)b;
} else if ((b & 0x30) == 0x10) {
b &= 0xf0;

int joy = 0;
if (gbSgbMode && gbSgbMultiplayer) {
switch (gbSgbNextController) {
case 0x0f:
joy = 0;
break;
case 0x0e:
joy = 1;
break;
case 0x0d:
joy = 2;
break;
case 0x0c:
joy = 3;
break;
default:
joy = 0;
}
// Choose joystick index for SGB multiplayer if enabled, otherwise 0
int joy = 0;

if (gbSgbMode && gbSgbMultiplayer) {
switch (gbSgbNextController) {
case 0x0f: joy = 0; break;
case 0x0e: joy = 1; break;
case 0x0d: joy = 2; break;
case 0x0c: joy = 3; break;
default: joy = 0; break;
}
int joystate = gbJoymask[joy];
if (!(joystate & 8))
b |= 0x08;
if (!(joystate & 4))
b |= 0x04;
if (!(joystate & 2))
b |= 0x02;
if (!(joystate & 1))
b |= 0x01;

gbMemory[0xff00] = (uint8_t)b;
} else {
}

int joystate = gbJoymask[joy];

if (gbSgbMode && gbSgbMultiplayer) {
}

// Bit 7 - Not used
// Bit 6 - Not used
// Bit 5 - P15 Select Action buttons (0=Select)
// Bit 4 - P14 Select Direction buttons (0=Select)
// Bit 3 - P13 Input: Down or Start (0=Pressed) (Read Only)
// Bit 2 - P12 Input: Up or Select (0=Pressed) (Read Only)
// Bit 1 - P11 Input: Left or B (0=Pressed) (Read Only)
// Bit 0 - P10 Input: Right or A (0=Pressed) (Read Only)
uint8_t data_dir =
(!(joystate & 0x80) ? 0x08 : 0x00) | // Down -> bit3
(!(joystate & 0x40) ? 0x04 : 0x00) | // Up -> bit2
(!(joystate & 0x20) ? 0x02 : 0x00) | // Left -> bit1
(!(joystate & 0x10) ? 0x01 : 0x00); // Right-> bit0

uint8_t data_action =
(!(joystate & 0x08) ? 0x08 : 0x00) | // Start -> bit3
(!(joystate & 0x04) ? 0x04 : 0x00) | // Select -> bit2
(!(joystate & 0x02) ? 0x02 : 0x00) | // B -> bit1
(!(joystate & 0x01) ? 0x01 : 0x00); // A -> bit0

b &= 0xf0; // keep selector bits in upper nibble
switch (b & 0x30) {
case 0x00: b |= data_dir & data_action; break;
case 0x10: b |= data_action; break;
case 0x20: b |= data_dir; break;
case 0x30:
if (gbSgbMode && gbSgbMultiplayer) {
gbMemory[0xff00] = 0xf0 | gbSgbNextController;
b = 0xf0 | gbSgbNextController;
} else {
gbMemory[0xff00] = 0xff;
b = 0xff;
}
break;
}
gbMemory[0xff00] = b;
}
}
return gbMemory[0xff00];
break;
case 0x01:
return gbMemory[0xff01];
case 0x02:
Expand Down
125 changes: 84 additions & 41 deletions src/core/gba/gbaInline.h
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Original file line number Diff line number Diff line change
Expand Up @@ -123,6 +123,31 @@ static inline uint16_t ROMReadOOB(uint32_t address) {
return (address >> 1) & 0xFFFF;
}

static inline bool IsGPIO(uint32_t address) {
// TODO: Need to check which GPIO feature really is enabled
return (address == 0x80000c4 || address == 0x80000c6 || address == 0x80000c8);
}

// used for ROM boundary check
static inline bool IsEEPROM(uint32_t address) {
return (cpuEEPROMEnabled && (address & eepromMask) == eepromMask);
}

static inline bool isSaveGame() {
return (coreOptions.saveType != 5) && (!eepromInUse || cpuSramEnabled || cpuFlashEnabled);
}

// Reads sram or flash
static inline uint8_t CPUReadBackup(uint32_t address) {
return flashRead(address);
}

// writes sram or flash
static inline void CPUWriteBackup(uint32_t address, uint8_t value) {
if (cpuSaveGameFunc)
(*cpuSaveGameFunc)(address, value);
}

static inline uint32_t CPUReadMemory(uint32_t address)
{
#ifdef VBAM_ENABLE_DEBUGGER
Expand All @@ -133,7 +158,7 @@ static inline uint32_t CPUReadMemory(uint32_t address)
}
}
#endif
uint32_t value = 0xFFFFFFFF;
uint32_t value = 0;

switch (address >> 24) {
case REGION_BIOS:
Expand Down Expand Up @@ -194,27 +219,34 @@ static inline uint32_t CPUReadMemory(uint32_t address)
case REGION_ROM1:
case REGION_ROM1EX:
case REGION_ROM2:
if ((address & 0x01FFFFFC) <= (gbaGetRomSize() - 4))
if (IsEEPROM(address))
return 0; // ignore reads from eeprom region outside 0x0D page reads
else if ((address & 0x01FFFFFC) <= (gbaGetRomSize() - 4))
value = READ32LE(((uint32_t *)&g_rom[address & 0x01FFFFFC]));
else if (cpuEEPROMEnabled && ((address & eepromMask) == eepromMask))
return 0; // ignore reads from eeprom region outside 0x0D page reads
else {
value = (uint16_t)ROMReadOOB(address & 0x01FFFFFC);
value |= (uint16_t)ROMReadOOB((address & 0x01FFFFFC) + 2) << 16;
}
break;
case REGION_ROM2EX:
if (cpuEEPROMEnabled)
// no need to swap this
return eepromRead(address);
goto unreadable;
case REGION_SRAM:
case REGION_SRAMEX:
if (cpuFlashEnabled | cpuSramEnabled) { // no need to swap this
value = flashRead(address) * 0x01010101;
if (isSaveGame()) {
value = CPUReadBackup(address) * 0x01010101;
break;
}
/* fallthrough */
#ifdef GBA_LOGGING
// Just normal log, not openbus
if (systemVerbose & VERBOSE_ILLEGAL_READ) {
log("Illegal word read: %08x at %08x\n",
address,
armMode ? armNextPC - 4 : armNextPC - 2);
}
#endif
return 0xffffffff;
default:
unreadable:
#ifdef GBA_LOGGING
Expand Down Expand Up @@ -274,7 +306,7 @@ static inline uint32_t CPUReadHalfWord(uint32_t address)
}
#endif

uint32_t value = 0xFFFFFFFF;
uint32_t value = 0;

switch (address >> 24) {
case REGION_BIOS:
Expand Down Expand Up @@ -349,28 +381,35 @@ static inline uint32_t CPUReadHalfWord(uint32_t address)
case REGION_ROM1:
case REGION_ROM1EX:
case REGION_ROM2:
if ((address & 0x01FFFFFE) <= (gbaGetRomSize() - 2))
value = READ16LE(((uint16_t *)&g_rom[address & 0x01FFFFFE]));
else if (address == 0x80000c4 || address == 0x80000c6 || address == 0x80000c8)
if (IsGPIO(address))
value = rtcRead(address);
else if (cpuEEPROMEnabled && ((address & eepromMask) == eepromMask))
else if (IsEEPROM(address))
return 0; // ignore reads from eeprom region outside 0x0D page reads
else if ((address & 0x01FFFFFE) <= (gbaGetRomSize() - 2))
value = READ16LE(((uint16_t *)&g_rom[address & 0x01FFFFFE]));
else
value = (uint16_t)ROMReadOOB(address & 0x01FFFFFE);
break;
case REGION_ROM2EX:
if (cpuEEPROMEnabled)
// no need to swap this
return eepromRead(address);
goto unreadable;
case REGION_SRAM:
case REGION_SRAMEX:
if (cpuFlashEnabled | cpuSramEnabled) {
// no need to swap this
value = flashRead(address) * 0x0101;
if (isSaveGame()) {
value = CPUReadBackup(address) * 0x0101;
break;
}
/* fallthrough */
#ifdef GBA_LOGGING
// Just normal log, not openbus
if (systemVerbose & VERBOSE_ILLEGAL_READ) {
log("Illegal halfword read: %08x at %08x (%08x)\n",
address,
reg[15].I,
value);
}
#endif
return 0xffff;
default:
unreadable:
#ifdef GBA_LOGGING
Expand Down Expand Up @@ -469,20 +508,21 @@ static inline uint8_t CPUReadByte(uint32_t address)
case REGION_ROM1:
case REGION_ROM1EX:
case REGION_ROM2:
if ((address & 0x01FFFFFF) <= gbaGetRomSize())
return g_rom[address & 0x01FFFFFF];
else if (cpuEEPROMEnabled && ((address & eepromMask) == eepromMask))
if (IsEEPROM(address))
return 0; // ignore reads from eeprom region outside 0x0D page reads
return (uint8_t)ROMReadOOB(address & 0x01FFFFFE);
else if ((address & 0x01FFFFFF) <= gbaGetRomSize())
return g_rom[address & 0x01FFFFFF];
else
return (uint8_t)ROMReadOOB(address & 0x01FFFFFE);
case REGION_ROM2EX:
if (cpuEEPROMEnabled)
return DowncastU8(eepromRead(address));
goto unreadable;
case REGION_SRAM:
case REGION_SRAMEX:
if (cpuSramEnabled | cpuFlashEnabled)
return flashRead(address);

if (isSaveGame()) {
return CPUReadBackup(address);
}
switch (address & 0x00008f00) {
case 0x8200:
return DowncastU8(systemGetSensorX());
Expand All @@ -493,7 +533,15 @@ static inline uint8_t CPUReadByte(uint32_t address)
case 0x8500:
return DowncastU8(systemGetSensorY() >> 8);
}
return 0xFF;
#ifdef GBA_LOGGING
// Just normal log, not openbus
if (systemVerbose & VERBOSE_ILLEGAL_READ) {
log("Illegal byte read: %08x at %08x\n",
address,
armMode ? armNextPC - 4 : armNextPC - 2);
}
#endif
return 0xff;
default:
unreadable:
#ifdef GBA_LOGGING
Expand Down Expand Up @@ -603,12 +651,11 @@ static inline void CPUWriteMemory(uint32_t address, uint32_t value)
goto unwritable;
case REGION_SRAM:
case REGION_SRAMEX:
if ((!eepromInUse) | cpuSramEnabled | cpuFlashEnabled) {
(*cpuSaveGameFunc)(address, (uint8_t)(value >> (8 * (address & 3))));
if (isSaveGame()) {
CPUWriteBackup(address, (uint8_t)(value >> (8 * (address & 3))));
break;
}
goto unwritable;
// fallthrough
// fallthrough
default:
unwritable:
#ifdef GBA_LOGGING
Expand Down Expand Up @@ -704,7 +751,7 @@ static inline void CPUWriteHalfWord(uint32_t address, uint16_t value)
GBAMatrixWrite16(&GBAMatrix, address & 0x3C, value);
break;
}
if (address == 0x80000c4 || address == 0x80000c6 || address == 0x80000c8) {
if (IsGPIO(address)) {
if (!rtcWrite(address, value))
goto unwritable;
} else if (!agbPrintWrite(address, value))
Expand All @@ -727,11 +774,11 @@ static inline void CPUWriteHalfWord(uint32_t address, uint16_t value)
goto unwritable;
case REGION_SRAM:
case REGION_SRAMEX:
if ((!eepromInUse) | cpuSramEnabled | cpuFlashEnabled) {
(*cpuSaveGameFunc)(address, (uint8_t)(value >> (8 * (address & 1))));
if (isSaveGame()) {
CPUWriteBackup(address, (uint8_t)(value >> (8 * (address & 1))));
break;
}
/* fallthrough */
// fallthrough
default:
unwritable:
#ifdef GBA_LOGGING
Expand Down Expand Up @@ -867,9 +914,6 @@ static inline void CPUWriteByte(uint32_t address, uint8_t b)
}
break;
case REGION_OAM:
// no need to switch
// byte writes to OAM are ignored
// *((uint16_t *)&g_oam[address & 0x3FE]) = (b << 8) | b;
break;
case REGION_ROM2EX:
if (cpuEEPROMEnabled) {
Expand All @@ -879,12 +923,11 @@ static inline void CPUWriteByte(uint32_t address, uint8_t b)
goto unwritable;
case REGION_SRAM:
case REGION_SRAMEX:
if ((coreOptions.saveType != 5) && ((!eepromInUse) | cpuSramEnabled | cpuFlashEnabled)) {
(*cpuSaveGameFunc)(address, b);
if (isSaveGame()) {
CPUWriteBackup(address, b);
break;
}
goto unwritable;
// default
// fallthrough
default:
unwritable:
#ifdef GBA_LOGGING
Expand Down
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