actually finish the audio interpolation feature

also fix up UI details while we're at it

src/SPU.cpp

@@ -18,6 +18,7 @@
 
 #include <stdio.h>
 #include <string.h>
+#include <cmath>
 #include "Platform.h"
 #include "NDS.h"
 #include "DSi.h"
@@ -27,7 +28,6 @@
 // SPU TODO
 // * capture addition modes, overflow bugs
 // * channel hold
-// * 'length less than 4' glitch
 
 namespace SPU
 {
@@ -62,6 +62,12 @@ const s16 PSGTable[8][8] =
     {-0x7FFF, -0x7FFF, -0x7FFF, -0x7FFF, -0x7FFF, -0x7FFF, -0x7FFF, -0x7FFF}
 };
 
+// audio interpolation is an improvement upon the original hardware
+// (which performs no interpolation)
+int InterpType;
+s16 InterpCos[0x100];
+s16 InterpCubic[0x100][4];
+
 const u32 OutputBufferSize = 2*2048;
 s16 OutputBackbuffer[2 * OutputBufferSize];
 u32 OutputBackbufferWritePosition;
@@ -90,6 +96,32 @@ bool Init()
 
     AudioLock = Platform::Mutex_Create();
 
+    InterpType = 0;
+
+    // generate interpolation tables
+    // values are 1:1:14 fixed-point
+
+    float m_pi = std::acos(-1.0f);
+    for (int i = 0; i < 0x100; i++)
+    {
+        float ratio = (i * m_pi) / 255.0f;
+        ratio = 1.0f - std::cos(ratio);
+
+        InterpCos[i] = (s16)(ratio * 0x2000);
+    }
+
+    for (int i = 0; i < 0x100; i++)
+    {
+        s32 i1 = i << 6;
+        s32 i2 = (i * i) >> 2;
+        s32 i3 = (i * i * i) >> 10;
+
+        InterpCubic[i][0] = -i3 + 2*i2 - i1;
+        InterpCubic[i][1] = i3 - 2*i2 + 0x4000;
+        InterpCubic[i][2] = -i3 + i2 + i1;
+        InterpCubic[i][3] = i3 - i2;
+    }
+
     return true;
 }
 
@@ -148,6 +180,11 @@ void DoSavestate(Savestate* file)
 }
 
 
+void SetInterpolation(int type)
+{
+    InterpType = type;
+}
+
 void SetBias(u16 bias)
 {
     Bias = bias;
@@ -202,6 +239,7 @@ void Channel::DoSavestate(Savestate* file)
     file->Var8((u8*)&KeyOn);
     file->Var32(&Timer);
     file->Var32((u32*)&Pos);
+    file->VarArray(PrevSample, sizeof(PrevSample));
     file->Var16((u16*)&CurSample);
     file->Var16(&NoiseVal);
 
@@ -215,7 +253,7 @@ void Channel::DoSavestate(Savestate* file)
     file->Var32(&FIFOWritePos);
     file->Var32(&FIFOReadOffset);
     file->Var32(&FIFOLevel);
-    file->VarArray(FIFO, 8*4);
+    file->VarArray(FIFO, sizeof(FIFO));
 }
 
 void Channel::FIFO_BufferData()
@@ -269,7 +307,9 @@ void Channel::Start()
         Pos = -3;
 
     NoiseVal = 0x7FFF;
-    PrevSample = 0;
+    PrevSample[0] = 0;
+    PrevSample[1] = 0;
+    PrevSample[2] = 0;
     CurSample = 0;
 
     FIFOReadPos = 0;
@@ -445,7 +485,15 @@ s32 Channel::Run()
     {
         Timer = TimerReload + (Timer - 0x10000);
 
-        PrevSample = CurSample;
+        // for optional interpolation: save previous samples
+        // the interpolated audio will be delayed by a couple samples,
+        // but it's easier to deal with this way
+        if ((type < 3) && (InterpType != 0))
+        {
+            PrevSample[2] = PrevSample[1];
+            PrevSample[1] = PrevSample[0];
+            PrevSample[0] = CurSample;
+        }
 
         switch (type)
         {
@@ -459,15 +507,31 @@ s32 Channel::Run()
 
     s32 val = (s32)CurSample;
 
-    // interpolation
-    // now you get to enjoy Electric Angel in high quality I guess.
-    // TODO MAKE CONDITIONAL!!!
-    if (true)
+    // interpolation (emulation improvement, not a hardware feature)
+    if ((type < 3) && (InterpType != 0))
     {
-        s32 samplepos = ((Timer - TimerReload) * 0x1000) / (0x10000 - TimerReload);
-//printf("CHANNEL %d POS=%d SAMPLEPOS=%08X (%04X/%04X)\n", Num, Pos, samplepos, Timer, TimerReload);
-        val = ((val * samplepos) + (PrevSample * (0x1000-samplepos))) >> 12;
-        //printf("ASSDERP = %08X/%08X => %08X\n", CurSample, PrevSample, val);
+        s32 samplepos = ((Timer - TimerReload) * 0x100) / (0x10000 - TimerReload);
+        if (samplepos > 0xFF) samplepos = 0xFF;
+
+        switch (InterpType)
+        {
+        case 1: // linear
+            val = ((val           * samplepos) +
+                   (PrevSample[0] * (0xFF-samplepos))) >> 8;
+            break;
+
+        case 2: // cosine
+            val = ((val           * InterpCos[samplepos]) +
+                   (PrevSample[0] * InterpCos[0xFF-samplepos])) >> 14;
+            break;
+
+        case 3: // cubic
+            val = ((PrevSample[2] * InterpCubic[samplepos][0]) +
+                   (PrevSample[1] * InterpCubic[samplepos][1]) +
+                   (PrevSample[0] * InterpCubic[samplepos][2]) +
+                   (val           * InterpCubic[samplepos][3])) >> 14;
+            break;
+        }
     }
 
     val <<= VolumeShift;

src/SPU.h

@@ -31,6 +31,9 @@ void Stop();
 
 void DoSavestate(Savestate* file);
 
+// 0=none 1=linear 2=cosine 3=cubic
+void SetInterpolation(int type);
+
 void SetBias(u16 bias);
 
 void Mix(u32 dummy);
@@ -73,7 +76,7 @@ public:
     bool KeyOn;
     u32 Timer;
     s32 Pos;
-    s16 PrevSample;
+    s16 PrevSample[3];
     s16 CurSample;
     u16 NoiseVal;
 

src/frontend/qt_sdl/AudioSettingsDialog.cpp

@@ -38,8 +38,15 @@ AudioSettingsDialog::AudioSettingsDialog(QWidget* parent) : QDialog(parent), ui(
     ui->setupUi(this);
     setAttribute(Qt::WA_DeleteOnClose);
 
+    oldInterp = Config::AudioInterp;
     oldVolume = Config::AudioVolume;
 
+    ui->cbInterpolation->addItem("None");
+    ui->cbInterpolation->addItem("Linear");
+    ui->cbInterpolation->addItem("Cosine");
+    ui->cbInterpolation->addItem("Cubic");
+    ui->cbInterpolation->setCurrentIndex(Config::AudioInterp);
+
     ui->slVolume->setValue(Config::AudioVolume);
 
     grpMicMode = new QButtonGroup(this);
@@ -73,11 +80,22 @@ void AudioSettingsDialog::on_AudioSettingsDialog_accepted()
 
 void AudioSettingsDialog::on_AudioSettingsDialog_rejected()
 {
+    Config::AudioInterp = oldInterp;
     Config::AudioVolume = oldVolume;
 
     closeDlg();
 }
 
+void AudioSettingsDialog::on_cbInterpolation_currentIndexChanged(int idx)
+{
+    // prevent a spurious change
+    if (ui->cbInterpolation->count() < 4) return;
+
+    Config::AudioInterp = ui->cbInterpolation->currentIndex();
+
+    emit updateAudioSettings();
+}
+
 void AudioSettingsDialog::on_slVolume_valueChanged(int val)
 {
     Config::AudioVolume = val;

src/frontend/qt_sdl/AudioSettingsDialog.h

@@ -51,10 +51,14 @@ public:
         currentDlg = nullptr;
     }
 
+signals:
+    void updateAudioSettings();
+
 private slots:
     void on_AudioSettingsDialog_accepted();
     void on_AudioSettingsDialog_rejected();
 
+    void on_cbInterpolation_currentIndexChanged(int idx);
     void on_slVolume_valueChanged(int val);
     void onChangeMicMode(int mode);
     void on_btnMicWavBrowse_clicked();
@@ -62,6 +66,7 @@ private slots:
 private:
     Ui::AudioSettingsDialog* ui;
 
+    int oldInterp;
     int oldVolume;
     QButtonGroup* grpMicMode;
 };

src/frontend/qt_sdl/AudioSettingsDialog.ui

@@ -7,7 +7,7 @@
     <x>0</x>
     <y>0</y>
     <width>482</width>
-    <height>230</height>
+    <height>256</height>
    </rect>
   </property>
   <property name="sizePolicy">
@@ -29,14 +29,14 @@
       <string>Audio output</string>
      </property>
      <layout class="QGridLayout" name="gridLayout_2">
-      <item row="0" column="0">
+      <item row="1" column="0">
        <widget class="QLabel" name="label">
         <property name="text">
          <string>Volume:</string>
         </property>
        </widget>
       </item>
-      <item row="0" column="1">
+      <item row="1" column="1">
        <widget class="QSlider" name="slVolume">
         <property name="whatsThis">
          <string>&lt;html&gt;&lt;head/&gt;&lt;body&gt;&lt;p&gt;Controls the volume of the audio output.&lt;/p&gt;&lt;/body&gt;&lt;/html&gt;</string>
@@ -52,6 +52,20 @@
         </property>
        </widget>
       </item>
+      <item row="0" column="0">
+       <widget class="QLabel" name="label_2">
+        <property name="text">
+         <string>Interpolation:</string>
+        </property>
+       </widget>
+      </item>
+      <item row="0" column="1">
+       <widget class="QComboBox" name="cbInterpolation">
+        <property name="whatsThis">
+         <string>&lt;html&gt;&lt;head/&gt;&lt;body&gt;&lt;p&gt;Applies interpolation to audio samples for better quality. Option &amp;quot;None&amp;quot; is accurate to DS hardware.&lt;/p&gt;&lt;/body&gt;&lt;/html&gt;</string>
+        </property>
+       </widget>
+      </item>
      </layout>
     </widget>
    </item>

src/frontend/qt_sdl/EmuSettingsDialog.ui

@@ -354,21 +354,21 @@
        <item row="2" column="0">
         <widget class="QCheckBox" name="chkJITBranchOptimisations">
          <property name="text">
-          <string>Branch Optimisations</string>
+          <string>Branch optimisations</string>
          </property>
         </widget>
        </item>
        <item row="3" column="0">
         <widget class="QCheckBox" name="chkJITLiteralOptimisations">
          <property name="text">
-          <string>Literal Optimisations</string>
+          <string>Literal optimisations</string>
          </property>
         </widget>
        </item>
        <item row="4" column="0">
         <widget class="QCheckBox" name="chkJITFastMemory">
          <property name="text">
-          <string>Fast Memory</string>
+          <string>Fast memory</string>
          </property>
         </widget>
        </item>

src/frontend/qt_sdl/PlatformConfig.cpp

@@ -69,6 +69,7 @@ int DirectLAN;
 
 int SavestateRelocSRAM;
 
+int AudioInterp;
 int AudioVolume;
 int MicInputType;
 char MicWavPath[1024];
@@ -177,6 +178,7 @@ ConfigEntry PlatformConfigFile[] =
 
     {"SavStaRelocSRAM", 0, &SavestateRelocSRAM, 0, NULL, 0},
 
+    {"AudioInterp", 0, &AudioInterp, 0, NULL, 0},
     {"AudioVolume", 0, &AudioVolume, 256, NULL, 0},
     {"MicInputType", 0, &MicInputType, 1, NULL, 0},
     {"MicWavPath", 1, MicWavPath, 0, "", 1023},
@@ -199,7 +201,7 @@ ConfigEntry PlatformConfigFile[] =
     {"MouseHide",        0, &MouseHide,        0, NULL, 0},
     {"MouseHideSeconds", 0, &MouseHideSeconds, 5, NULL, 0},
     {"PauseLostFocus",   0, &PauseLostFocus,   0, NULL, 0},
-    
+
     {"", -1, NULL, 0, NULL, 0}
 };
 

src/frontend/qt_sdl/PlatformConfig.h

@@ -85,6 +85,7 @@ extern int DirectLAN;
 
 extern int SavestateRelocSRAM;
 
+extern int AudioInterp;
 extern int AudioVolume;
 extern int MicInputType;
 extern char MicWavPath[1024];

src/frontend/qt_sdl/WifiSettingsDialog.cpp

@@ -144,12 +144,12 @@ void WifiSettingsDialog::on_cbxDirectAdapter_currentIndexChanged(int sel)
     LAN_PCap::AdapterData* adapter = &LAN_PCap::Adapters[sel];
     char tmp[64];
 
-    sprintf(tmp, "MAC: %02X:%02X:%02X:%02X:%02X:%02X",
+    sprintf(tmp, "%02X:%02X:%02X:%02X:%02X:%02X",
             adapter->MAC[0], adapter->MAC[1], adapter->MAC[2],
             adapter->MAC[3], adapter->MAC[4], adapter->MAC[5]);
     ui->lblAdapterMAC->setText(QString(tmp));
 
-    sprintf(tmp, "IP: %d.%d.%d.%d",
+    sprintf(tmp, "%d.%d.%d.%d",
             adapter->IP_v4[0], adapter->IP_v4[1],
             adapter->IP_v4[2], adapter->IP_v4[3]);
     ui->lblAdapterIP->setText(QString(tmp));

src/frontend/qt_sdl/WifiSettingsDialog.ui

@@ -61,7 +61,7 @@
       <item row="3" column="0" rowspan="3" colspan="2">
        <widget class="QGroupBox" name="groupBox_3">
         <property name="title">
-         <string>Direct Mode Settings</string>
+         <string>Direct mode settings</string>
         </property>
         <layout class="QGridLayout" name="gridLayout_3">
          <item row="0" column="0">
@@ -127,7 +127,7 @@
          <string>&lt;html&gt;&lt;head/&gt;&lt;body&gt;&lt;p&gt;Indirect mode uses libslirp. It requires no extra setup and is easy to use.&lt;/p&gt;&lt;/body&gt;&lt;/html&gt;</string>
         </property>
         <property name="text">
-         <string>Indirect Mode (uses libslirp, recommended)</string>
+         <string>Indirect mode (uses libslirp, recommended)</string>
         </property>
        </widget>
       </item>

src/frontend/qt_sdl/main.cpp

@@ -363,6 +363,8 @@ void EmuThread::run()
     GPU::InitRenderer(videoRenderer);
     GPU::SetRenderSettings(videoRenderer, videoSettings);
 
+    SPU::SetInterpolation(Config::AudioInterp);
+
     Input::Init();
 
     u32 nframes = 0;
@@ -2388,11 +2390,19 @@ void MainWindow::onOpenVideoSettings()
 void MainWindow::onOpenAudioSettings()
 {
     AudioSettingsDialog* dlg = AudioSettingsDialog::openDlg(this);
+    connect(dlg, &AudioSettingsDialog::updateAudioSettings, this, &MainWindow::onUpdateAudioSettings);
     connect(dlg, &AudioSettingsDialog::finished, this, &MainWindow::onAudioSettingsFinished);
 }
 
+void MainWindow::onUpdateAudioSettings()
+{
+    SPU::SetInterpolation(Config::AudioInterp);
+}
+
 void MainWindow::onAudioSettingsFinished(int res)
 {
+    SPU::SetInterpolation(Config::AudioInterp);
+
     if (Config::MicInputType == 3)
     {
         micLoadWav(Config::MicWavPath);
@@ -2710,6 +2720,7 @@ int main(int argc, char** argv)
     );
     SANITIZE(Config::ScreenVSyncInterval, 1, 20);
     SANITIZE(Config::GL_ScaleFactor, 1, 16);
+    SANITIZE(Config::AudioInterp, 0, 3);
     SANITIZE(Config::AudioVolume, 0, 256);
     SANITIZE(Config::MicInputType, 0, 3);
     SANITIZE(Config::ScreenRotation, 0, 3);

src/frontend/qt_sdl/main.h

@@ -243,6 +243,7 @@ private slots:
     void onInputConfigFinished(int res);
     void onOpenVideoSettings();
     void onOpenAudioSettings();
+    void onUpdateAudioSettings();
     void onAudioSettingsFinished(int res);
     void onOpenWifiSettings();
     void onWifiSettingsFinished(int res);