Add accelerator input MMIO register, fix MMIO PCM modes

Source/Core/Core/DSP/DSPAccelerator.cpp

@@ -118,16 +118,6 @@ u16 Accelerator::ReadSample(const s16* coefs)
   if (m_reads_stopped)
     return 0x0000;
 
-  if (m_sample_format.raw_only)
-  {
-    // Seems to return garbage on hardware
-    ERROR_LOG_FMT(
-        DSPLLE,
-        "dsp_read_accelerator_sample() tried sample read with raw only bit set for format {:#x}",
-        m_sample_format.hex);
-    return 0x0000;
-  }
-
   if (m_sample_format.unk != 0)
   {
     WARN_LOG_FMT(DSPLLE, "dsp_read_accelerator_sample() format {:#x} has unknown upper bits set",
@@ -136,8 +126,18 @@ u16 Accelerator::ReadSample(const s16* coefs)
 
   u16 val = 0;
   u8 step_size = 0;
+  s16 raw_sample;
+  if (m_sample_format.decode == FormatDecode::MMIOPCMHalt ||
+      m_sample_format.decode == FormatDecode::MMIOPCMInc)
+  {
+    // The addresses can be complete nonsense in either of these modes
+    raw_sample = m_input;
+  }
+  else
+  {
+    raw_sample = GetCurrentSample();
+  }
 
-  s16 raw_sample = GetCurrentSample();
   int coef_idx = (m_pred_scale >> 4) & 0x7;
 
   s32 coef1 = coefs[coef_idx * 2 + 0];
@@ -184,7 +184,9 @@ u16 Accelerator::ReadSample(const s16* coefs)
     }
     break;
   }
+  case FormatDecode::MMIOPCMHalt:
   case FormatDecode::PCM:  // 16-bit PCM audio
+  case FormatDecode::MMIOPCMInc:
   {
     // Gain seems to only apply for PCM decoding
     u8 gain_shift = 0;
@@ -210,7 +212,10 @@ u16 Accelerator::ReadSample(const s16* coefs)
     m_yn2 = m_yn1;
     m_yn1 = val;
     step_size = 2;
-    m_current_address += 1;
+    if (m_sample_format.decode != FormatDecode::MMIOPCMHalt)
+    {
+      m_current_address += 1;
+    }
     break;
   }
   }
@@ -286,4 +291,10 @@ void Accelerator::SetPredScale(u16 pred_scale)
 {
   m_pred_scale = pred_scale & 0x7f;
 }
+
+void Accelerator::SetInput(u16 input)
+{
+  m_input = input;
+}
+
 }  // namespace DSP

Source/Core/Core/DSP/DSPAccelerator.h

@@ -28,6 +28,7 @@ public:
   s16 GetYn1() const { return m_yn1; }
   s16 GetYn2() const { return m_yn2; }
   u16 GetPredScale() const { return m_pred_scale; }
+  u16 GetInput() const { return m_input; }
   void SetStartAddress(u32 address);
   void SetEndAddress(u32 address);
   void SetCurrentAddress(u32 address);
@@ -36,6 +37,7 @@ public:
   void SetYn1(s16 yn1);
   void SetYn2(s16 yn2);
   void SetPredScale(u16 pred_scale);
+  void SetInput(u16 input);
 
   void DoState(PointerWrap& p);
 
@@ -62,8 +64,10 @@ protected:
 
   enum class FormatDecode : u16
   {
-    ADPCM = 0,
-    PCM = 1,
+    ADPCM = 0,        // ADPCM reads from ARAM, ACCA increments
+    MMIOPCMHalt = 1,  // PCM Reads from ACIN, ACCA doesn't increment
+    PCM = 2,          // PCM reads from ARAM, ACCA increments
+    MMIOPCMInc = 3    // PCM reads from ACIN, ACCA increments
   };
 
   // When reading samples (at least in PCM mode), they are multiplied by the gain, then shifted
@@ -80,9 +84,7 @@ protected:
   {
     u16 hex;
     BitField<0, 2, FormatSize> size;
-    BitField<2, 1, bool, u16>
-        raw_only;  // When this bit is set, sample reads seem broken, while raw accesses work
-    BitField<3, 1, FormatDecode> decode;
+    BitField<2, 2, FormatDecode> decode;
     BitField<4, 2, FormatGainCfg> gain_cfg;
     BitField<6, 10, u16> unk;
   } m_sample_format{0};
@@ -91,6 +93,7 @@ protected:
   s16 m_yn1 = 0;
   s16 m_yn2 = 0;
   u16 m_pred_scale = 0;
+  u16 m_input = 0;
 
   // When an ACCOV is triggered, the accelerator stops reading back anything
   // and updating the current address register, unless the YN2 register is written to.

Source/Core/Core/DSP/DSPCore.h

@@ -166,7 +166,7 @@ enum : u32
   DSP_YN2 = 0xdc,
   DSP_ACDSAMP = 0xdd,  // Accelerator sample reads, processed differently depending on FORMAT
   DSP_GAIN = 0xde,
-  DSP_ACUNK2 = 0xdf,  // Set to 0xc on my dumps
+  DSP_ACIN = 0xdf,  // Feeds PCM samples written here
 
   DSP_AMDM = 0xef,  // ARAM DMA Request Mask 0: DMA with ARAM unmasked 1: masked
 

Source/Core/Core/DSP/DSPHWInterface.cpp

@@ -170,6 +170,9 @@ void SDSP::WriteIFX(u32 address, u16 value)
   case DSP_ACDRAW:  // Raw accelerator write
     m_accelerator->WriteRaw(value);
     break;
+  case DSP_ACIN:
+    m_accelerator->SetInput(value);
+    break;
 
   default:
     if ((address & 0xff) >= 0xa0)
@@ -240,6 +243,8 @@ u16 SDSP::ReadIFXImpl(u16 address)
     return m_accelerator->ReadSample(reinterpret_cast<s16*>(&m_ifx_regs[DSP_COEF_A1_0]));
   case DSP_ACDRAW:  // Raw accelerator read
     return m_accelerator->ReadRaw();
+  case DSP_ACIN:
+    return m_accelerator->GetInput();
 
   default:
   {

Source/Core/Core/DSP/DSPTables.cpp

@@ -414,7 +414,7 @@ const std::array<pdlabel_t, 96> pdlabels =
   {0xffdc, "yn2", "yn2",},
   {0xffdd, "ARAM", "Direct Read from ARAM (uses ADPCM)",},
   {0xffde, "GAIN", "Gain",},
-  {0xffdf, "0xffdf", nullptr,},
+  {0xffdf, "ACIN", "Accelerator MMIO PCM input value",},
 
   {0xffe0, "0xffe0",nullptr,},
   {0xffe1, "0xffe1",nullptr,},