Add basic GBA GPIO support, solar sensor detection

2 files changed, 76 insertions, 3 deletions

diff --git a/src/GBACart.cpp b/src/GBACart.cpp
index b544519..75bc1dc 100644
--- a/src/GBACart.cpp
+++ b/src/GBACart.cpp
@@ -448,11 +448,34 @@ void Write32(u32 addr, u32 val)
 namespace GBACart

 {

 

+const char SOLAR_SENSOR_GAMECODES[10][5] =

+{

+    "U3IJ", // Bokura no Taiyou - Taiyou Action RPG (Japan)

+    "U3IE", // Boktai - The Sun Is in Your Hand (USA)

+    "U3IP", // Boktai - The Sun Is in Your Hand (Europe)

+    "U32J", // Zoku Bokura no Taiyou - Taiyou Shounen Django (Japan)

+    "U32E", // Boktai 2 - Solar Boy Django (USA)

+    "U32P", // Boktai 2 - Solar Boy Django (Europe)

+    "U33J", // Shin Bokura no Taiyou - Gyakushuu no Sabata (Japan)

+    "A3IJ"  // Boktai - The Sun Is in Your Hand (USA) (Sample)

+};

+

+

+struct GPIO

+{

+    bool has_solar_sensor;

+    u16 data;

+    u16 direction;

+    u16 control;

+};

+

+

 bool CartInserted;

 u8* CartROM;

 u32 CartROMSize;

 u32 CartCRC;

 u32 CartID;

+GPIO CartGPIO; // overridden GPIO parameters

 

 

 bool Init()

@@ -477,6 +500,7 @@ void Reset()
     if (CartROM) delete[] CartROM;

     CartROM = NULL;

     CartROMSize = 0;

+    CartGPIO = {};

 

     GBACart_SRAM::Reset();

 }

@@ -506,10 +530,20 @@ bool LoadROM(const char* path, const char* sram)
     while (CartROMSize < len)

         CartROMSize <<= 1;

 

-    u32 gamecode;

+    char gamecode[5] = { '\0' };

     fseek(f, 0xAC, SEEK_SET);

-    fread(&gamecode, 4, 1, f);

-    printf("Game code: %c%c%c%c\n", gamecode&0xFF, (gamecode>>8)&0xFF, (gamecode>>16)&0xFF, gamecode>>24);

+    fread(&gamecode, 1, 4, f);

+    printf("Game code: %s\n", gamecode);

+

+    for (int i = 0; i < sizeof(SOLAR_SENSOR_GAMECODES)/sizeof(SOLAR_SENSOR_GAMECODES[0]); i++)

+    {

+        if (strcmp(gamecode, SOLAR_SENSOR_GAMECODES[i]) == 0) CartGPIO.has_solar_sensor = true;

+    }

+

+    if (CartGPIO.has_solar_sensor)

+    {

+        printf("GBA solar sensor support detected!\n");

+    }

 

     CartROM = new u8[CartROMSize];

     memset(CartROM, 0, CartROMSize);

@@ -536,4 +570,41 @@ void RelocateSave(const char* path, bool write)
     GBACart_SRAM::RelocateSave(path, write);

 }

 

+// referenced from mGBA

+void WriteGPIO(u32 addr, u16 val)

+{

+    switch (addr)

+    {

+        case 0xC4:

+            CartGPIO.data &= ~CartGPIO.direction;

+            CartGPIO.data |= val & CartGPIO.direction;

+            // TODO: process pins

+            break;

+        case 0xC6:

+            CartGPIO.direction = val;

+            break;

+        case 0xC8:

+            CartGPIO.control = val;

+            break;

+        default:

+            printf("Unknown GBA GPIO write 0x%02X @ 0x%04X\n", val, addr);

+    }

+

+    // write the GPIO values in the ROM (if writable)

+    if (CartGPIO.control & 1)

+    {

+        *(u16*)&CartROM[addr] = CartGPIO.data;

+        *(u16*)&CartROM[addr + 2] = CartGPIO.direction;

+        *(u16*)&CartROM[addr + 4] = CartGPIO.control;

+    }

+    else

+    {

+        // GBATEK: "in write-only mode, reads return 00h (or [possibly] other data (...))"

+        // ambiguous, but mGBA sets ROM to 00h when switching to write-only, so do the same

+        *(u16*)&CartROM[addr] = 0;

+        *(u16*)&CartROM[addr + 2] = 0;

+        *(u16*)&CartROM[addr + 4] = 0;

+    }

+}

+

 }

diff --git a/src/GBACart.h b/src/GBACart.h
index 81fb222..22a3a60 100644
--- a/src/GBACart.h
+++ b/src/GBACart.h
@@ -55,6 +55,8 @@ void DoSavestate(Savestate* file);
 bool LoadROM(const char* path, const char* sram);

 void RelocateSave(const char* path, bool write);

 

+void WriteGPIO(u32 addr, u16 val);

+

 }

 

 #endif // GBACART_H