preliminary microphone code. requires an actual microphone. resulting audio is farty and blargy as fuck.

src/NDS.cpp

@@ -74,6 +74,7 @@ ARMv4* ARM7;
 u32 NumFrames;
 u64 SysClockCycles;
 u64 LastSysClockCycles;
+u32 FrameSysClockCycles;
 
 s32 CurIterationCycles;
 s32 ARM7Offset;
@@ -760,6 +761,8 @@ void RunSystem(s32 cycles)
 
 u32 RunFrame()
 {
+    FrameSysClockCycles = 0;
+
     if (!Running) return 263; // dorp
 
     GPU::StartFrame();
@@ -848,6 +851,7 @@ u32 RunFrame()
 
         SysClockCycles += ndscyclestorun;
         LastSysClockCycles += ndscyclestorun;
+        FrameSysClockCycles += ndscyclestorun;
     }
 
 #ifdef DEBUG_CHECK_DESYNC
@@ -949,6 +953,11 @@ void SetKeyMask(u32 mask)
     KeyInput |= key_lo | (key_hi << 16);
 }
 
+void MicInputFrame(s16* data, int samples)
+{
+    return SPI_TSC::MicInputFrame(data, samples);
+}
+
 
 void Halt()
 {
@@ -1111,14 +1120,15 @@ u64 GetSysClockCycles(int num)
 {
     u64 ret;
 
-    if (num == 0)
+    if (num == 0 || num == 2)
     {
-        ret = SysClockCycles;
+        if      (num == 0) ret = SysClockCycles;
+        else if (num == 2) ret = FrameSysClockCycles;
 
         if      (CurCPU == 1) ret += (ARM9->Cycles >> 1);
         else if (CurCPU == 2) ret += ARM7->Cycles;
     }
-    else
+    else if (num == 1)
     {
         ret = LastSysClockCycles;
         LastSysClockCycles = 0;

src/NDS.h

@@ -152,6 +152,8 @@ void ReleaseScreen();
 
 void SetKeyMask(u32 mask);
 
+void MicInputFrame(s16* data, int samples);
+
 void ScheduleEvent(u32 id, bool periodic, s32 delay, void (*func)(u32), u32 param);
 void CancelEvent(u32 id);
 
@@ -170,6 +172,7 @@ void GXFIFOStall();
 void GXFIFOUnstall();
 
 u32 GetPC(u32 cpu);
+u64 GetSysClockCycles(int num);
 void NocashPrint(u32 cpu, u32 addr);
 
 bool DMAsInMode(u32 cpu, u32 mode);

src/SPI.cpp

@@ -453,6 +453,9 @@ u16 ConvResult;
 
 u16 TouchX, TouchY;
 
+s16 MicBuffer[1024];
+int MicBufferLen;
+
 
 bool Init()
 {
@@ -469,6 +472,8 @@ void Reset()
     Data = 0;
 
     ConvResult = 0;
+
+    MicBufferLen = 0;
 }
 
 void DoSavestate(Savestate* file)
@@ -497,6 +502,13 @@ void SetTouchCoords(u16 x, u16 y)
     TouchY <<= 4;
 }
 
+void MicInputFrame(s16* data, int samples)
+{
+    if (samples > 1024) samples = 1024;
+    memcpy(MicBuffer, data, samples*sizeof(s16));
+    MicBufferLen = samples;
+}
+
 u8 Read()
 {
     return Data;
@@ -520,7 +532,30 @@ void Write(u8 val, u32 hold)
         {
         case 0x10: ConvResult = TouchY; break;
         case 0x50: ConvResult = TouchX; break;
-        case 0x60: ConvResult = 0x800; break; // TODO: mic
+
+        case 0x60:
+            {
+                if (MicBufferLen == 0)
+                    ConvResult = 0x800;
+                else
+                {
+                    // 560190 cycles per frame
+                    u32 cyclepos = (u32)NDS::GetSysClockCycles(2);
+                    u32 samplepos = (cyclepos * MicBufferLen) / 560190;
+                    s16 sample = MicBuffer[samplepos];
+
+                    // make it louder
+                    //if (sample > 0x3FFF) sample = 0x7FFF;
+                    //else if (sample < -0x4000) sample = -0x8000;
+                    //else sample <<= 1;
+
+                    // make it unsigned 12-bit
+                    sample ^= 0x8000;
+                    ConvResult = sample >> 4;
+                }
+            }
+            break;
+
         default: ConvResult = 0xFFF; break;
         }
 

src/SPI.h

@@ -36,6 +36,7 @@ namespace SPI_TSC
 {
 
 void SetTouchCoords(u16 x, u16 y);
+void MicInputFrame(s16* data, int samples);
 
 }
 

src/libui_sdl/main.cpp

@@ -109,6 +109,10 @@ bool Touching = false;
 u32 KeyInputMask;
 SDL_Joystick* Joystick;
 
+const u32 kMicBufferSize = 2048; // must be power of two
+s16 MicBuffer[kMicBufferSize];
+u32 MicBufferReadPos, MicBufferWritePos;
+
 
 void SetupScreenRects(int width, int height);
 
@@ -147,7 +151,6 @@ void AudioCallback(void* data, Uint8* stream, int len)
     // buffer length is 1024 samples
     // which is 710 samples at the original sample rate
 
-    //SPU::ReadOutput((s16*)stream, len>>2);
     s16 buf_in[710*2];
     s16* buf_out = (s16*)stream;
 
@@ -185,6 +188,23 @@ void AudioCallback(void* data, Uint8* stream, int len)
     }
 }
 
+void MicCallback(void* data, Uint8* stream, int len)
+{
+    s16* input = (s16*)stream;
+    len /= sizeof(s16);
+
+    if ((MicBufferWritePos + len) > kMicBufferSize)
+    {
+        u32 len1 = kMicBufferSize-MicBufferWritePos;
+        memcpy(&MicBuffer[MicBufferWritePos], &input[0], len1*sizeof(s16));
+        memcpy(&MicBuffer[0], &input[len1], (len-len1)*sizeof(s16));
+    }
+    else
+        memcpy(&MicBuffer[MicBufferWritePos], input, len*sizeof(s16));
+    MicBufferWritePos += len;
+    MicBufferWritePos &= (kMicBufferSize-1);
+}
+
 int EmuThreadFunc(void* burp)
 {
     NDS::Init();
@@ -254,6 +274,20 @@ int EmuThreadFunc(void* burp)
             }
             NDS::SetKeyMask(keymask & joymask);
 
+            // microphone input
+            if ((MicBufferReadPos + 735) > kMicBufferSize)
+            {
+                s16 tmp[735];
+                u32 len1 = kMicBufferSize-MicBufferReadPos;
+                memcpy(&tmp[0], &MicBuffer[MicBufferReadPos], len1*sizeof(s16));
+                memcpy(&tmp[len1], &MicBuffer[0], (735-len1)*sizeof(s16));
+                NDS::MicInputFrame(tmp, 735);
+            }
+            else
+                NDS::MicInputFrame(&MicBuffer[MicBufferReadPos], 735);
+            MicBufferReadPos += 735;
+            MicBufferReadPos &= (kMicBufferSize-1);
+
             // emulate
             u32 nlines = NDS::RunFrame();
 
@@ -1594,6 +1628,26 @@ int main(int argc, char** argv)
         SDL_PauseAudioDevice(audio, 0);
     }
 
+    memset(&whatIwant, 0, sizeof(SDL_AudioSpec));
+    whatIwant.freq = 44100;
+    whatIwant.format = AUDIO_S16LSB;
+    whatIwant.channels = 1;
+    whatIwant.samples = 1024;
+    whatIwant.callback = MicCallback;
+    audio = SDL_OpenAudioDevice(NULL, 1, &whatIwant, &whatIget, 0);
+    if (!audio)
+    {
+        printf("Mic init failed: %s\n", SDL_GetError());
+    }
+    else
+    {
+        SDL_PauseAudioDevice(audio, 0);
+    }
+
+    memset(MicBuffer, 0, sizeof(MicBuffer));
+    MicBufferReadPos = 0;
+    MicBufferWritePos = 0;
+
     // TODO: support more joysticks
     if (SDL_NumJoysticks() > 0)
         Joystick = SDL_JoystickOpen(0);