basic implementation of SNDExCnt

isn't hooked up to the DSP or microphone though
fixes memory abort in TwilightMenu

src/DSi.cpp

@@ -2638,6 +2638,9 @@ u8 ARM7IORead8(u32 addr)
     case 0x04004D06: if (SCFG_BIOS & (1<<10)) return 0; return (ConsoleID >> 48) & 0xFF;
     case 0x04004D07: if (SCFG_BIOS & (1<<10)) return 0; return ConsoleID >> 56;
     case 0x04004D08: return 0;
+
+    case 0x4004700: return DSi_DSP::SNDExCnt;
+    case 0x4004701: return DSi_DSP::SNDExCnt >> 8;
     }
 
     return NDS::ARM7IORead8(addr);
@@ -2670,6 +2673,8 @@ u16 ARM7IORead16(u32 addr)
     case 0x04004D04: if (SCFG_BIOS & (1<<10)) return 0; return (ConsoleID >> 32) & 0xFFFF;
     case 0x04004D06: if (SCFG_BIOS & (1<<10)) return 0; return ConsoleID >> 48;
     case 0x04004D08: return 0;
+    
+    case 0x4004700: return DSi_DSP::SNDExCnt;
     }
 
     if (addr >= 0x04004800 && addr < 0x04004A00)
@@ -2741,6 +2746,10 @@ u32 ARM7IORead32(u32 addr)
     case 0x04004D00: if (SCFG_BIOS & (1<<10)) return 0; return ConsoleID & 0xFFFFFFFF;
     case 0x04004D04: if (SCFG_BIOS & (1<<10)) return 0; return ConsoleID >> 32;
     case 0x04004D08: return 0;
+
+    case 0x4004700:
+        printf("32-Bit SNDExCnt read? %08X\n", NDS::ARM7->R[15]);
+        return DSi_DSP::SNDExCnt;
     }
 
     if (addr >= 0x04004800 && addr < 0x04004A00)
@@ -2788,6 +2797,13 @@ void ARM7IOWrite8(u32 addr, u8 val)
 
     case 0x04004500: DSi_I2C::WriteData(val); return;
     case 0x04004501: DSi_I2C::WriteCnt(val); return;
+
+    case 0x4004700:
+        DSi_DSP::WriteSNDExCnt((u16)val | (DSi_DSP::SNDExCnt & 0xFF00));
+        return;
+    case 0x4004701:
+        DSi_DSP::WriteSNDExCnt(((u16)val << 8) | (DSi_DSP::SNDExCnt & 0x00FF));
+        return;
     }
 
     return NDS::ARM7IOWrite8(addr, val);
@@ -2819,11 +2835,17 @@ void ARM7IOWrite16(u32 addr, u16 val)
         case 0x04004062:
             if (!(SCFG_EXT[1] & (1 << 31))) /* no access to SCFG Registers if disabled*/
                 return;
-            u32 tmp = MBK[0][8];
-            tmp &= ~(0xffff << ((addr % 4) * 8));
-            tmp |= (val << ((addr % 4) * 8));
-            MBK[0][8] = tmp & 0x00FFFF0F;
-            MBK[1][8] = MBK[0][8];
+            {
+                u32 tmp = MBK[0][8];
+                tmp &= ~(0xffff << ((addr % 4) * 8));
+                tmp |= (val << ((addr % 4) * 8));
+                MBK[0][8] = tmp & 0x00FFFF0F;
+                MBK[1][8] = MBK[0][8];
+            }
+            return;
+
+        case 0x4004700:
+            DSi_DSP::WriteSNDExCnt(val);
             return;
     }
 
@@ -2924,6 +2946,11 @@ void ARM7IOWrite32(u32 addr, u32 val)
     case 0x04004400: DSi_AES::WriteCnt(val); return;
     case 0x04004404: DSi_AES::WriteBlkCnt(val); return;
     case 0x04004408: DSi_AES::WriteInputFIFO(val); return;
+
+    case 0x4004700:
+        printf("32-Bit SNDExCnt write? %08X %08X\n", val, NDS::ARM7->R[15]);
+        DSi_DSP::WriteSNDExCnt(val);
+        return;
     }
 
     if (addr >= 0x04004420 && addr < 0x04004430)

src/DSi_DSP.cpp

@@ -27,6 +27,9 @@
 namespace DSi_DSP
 {
 
+// not sure whether to not rather put it somewhere else
+u16 SNDExCnt;
+
 Teakra::Teakra* TeakraCore;
 
 bool SCFG_RST;
@@ -151,6 +154,8 @@ void Reset()
     TeakraCore->Reset();
 
     NDS::CancelEvent(NDS::Event_DSi_DSP);
+
+    SNDExCnt = 0;
 }
 
 bool IsRstReleased()
@@ -548,6 +553,21 @@ void Write32(u32 addr, u32 val)
     Write16(addr, val & 0xFFFF);
 }
 
+void WriteSNDExCnt(u16 val)
+{
+    // it can be written even in NDS mode
+
+    // mic frequency can only be changed if it was disabled
+    // before the write
+    if (SNDExCnt & 0x8000)
+    {
+        val &= ~0x2000;
+        val |= SNDExCnt & 0x2000;
+    }
+
+    SNDExCnt = val & 0xE00F;
+}
+
 void Run(u32 cycles)
 {
     if (!IsDSPCoreEnabled())

src/DSi_DSP.h

@@ -24,11 +24,12 @@
 
 // TODO: for actual sound output
 // * audio callbacks
-// * SNDEXCNT
 
 namespace DSi_DSP
 {
 
+extern u16 SNDExCnt;
+
 extern u16 DSP_PDATA;
 extern u16 DSP_PADR;
 extern u16 DSP_PCFG;
@@ -65,6 +66,8 @@ void Write16(u32 addr, u16 val);
 u32 Read32(u32 addr);
 void Write32(u32 addr, u32 val);
 
+void WriteSNDExCnt(u16 val);
+
 // NOTE: checks SCFG_CLK9
 void Run(u32 cycles);