Added sync-tone function

AidanHockey5 · Jan 20, 2022 · 1eeb521 · 1eeb521
1 parent 84429d2
commit 1eeb521
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Showing 10 changed files with 424 additions and 8 deletions.
diff --git a/lib/VGMEngine/SN76489.cpp b/lib/VGMEngine/SN76489.cpp
@@ -39,8 +39,6 @@ void SN76489::write(uint8_t data)
         writeRaw(data);
 }
 
-
-
 void SN76489::writeRaw(uint8_t data)
 {
     //32 clock cycles is 280.11nS
@@ -53,4 +51,149 @@ void SN76489::writeRaw(uint8_t data)
     sleepClocks(NTSC_COLORBURST, 1);      //Safety delay so we don't slam into the second write cycle before the PSG is finished with the first
 }
 
+bool SN76489::UpdateNoiseControl()
+{
+    byte noiseControlData;
+
+    switch (currentNote[noiseCh]) 
+    {
+        case 60:
+            // Note: C4, Periodic noise, shift rate = clock speed (Hz) / 512
+            noiseControlData = 0x00;
+            break;
+
+        case 62:
+            // Note: D4, Periodic noise, shift rate = clock speed (Hz) / 1024
+            noiseControlData = 0x01;
+            break;
+
+        case 64:
+            // Note: E4, Periodic noise, shift rate = clock speed (Hz) / 2048
+            noiseControlData = 0x02;
+            break;
+
+        case 65:
+            // Note: F4, Perioic noise, shift rate = Square voice 3 frequency
+            noiseControlData = 0x03;
+            break;
+
+        case 67:
+            // Note: G4, White noise, shift rate = clock speed (Hz) / 512
+            noiseControlData = 0x04;
+            break;
+
+        case 69:
+            // Note: A4, White noise, shift rate = clock speed (Hz) / 1024
+            noiseControlData = 0x05;
+            break;
+
+        case 71:
+            // Note: B4, White noise, shift rate = clock speed (Hz) / 2048
+            noiseControlData = 0x06;
+            break;
+
+        case 72:
+            // Note: C5, White noise, shift rate = Square voice 3 frequency
+            noiseControlData = 0x07;
+            break;
+
+        default:
+            return false;
+    }
+
+    // Send the noise control byte to the SN76489 and return true
+    writeRaw(0x80 | 0x60 | noiseControlData);
+    return true;
+}
+
+void SN76489::SetNoiseOn(uint8_t key)
+{
+    currentNote[noiseCh] = key;
+    currentVelocity[noiseCh] = 127;
+    bool updateAttenuationFlag = UpdateNoiseControl();
+    if(updateAttenuationFlag)
+        UpdateAttenuation(noiseCh);
+}
+
+void SN76489::SetNoiseOff(uint8_t key)
+{
+    currentNote[noiseCh] = key;
+    currentVelocity[noiseCh] = 0;
+    bool updateAttenuationFlag = UpdateNoiseControl();
+    if(updateAttenuationFlag)
+        UpdateAttenuation(noiseCh);
+}
+
+void SN76489::SetChannelOn(uint8_t key, uint8_t voice)
+{
+    bool updateAttenuationFlag;
+    if(voice < MAX_CHANNELS_PSG)
+    {
+        currentNote[voice] = key;
+        currentVelocity[voice] = 127;
+        updateAttenuationFlag = UpdateSquarePitch(voice);
+        if (updateAttenuationFlag) 
+            UpdateAttenuation(voice);
+    }
+}
+
+void SN76489::SetChannelOff(uint8_t key, uint8_t voice)
+{
+    if (key != currentNote[voice])
+        return;
+    currentVelocity[voice] = 0;
+    UpdateAttenuation(voice);
+}
+
+bool SN76489::UpdateSquarePitch(uint8_t voice)
+{
+    float pitchInHz;
+    unsigned int frequencyData;
+    if (voice < 0 || voice > 2)
+        return false;
+    pitchInHz = 440 * pow(2, (float(currentNote[voice] - 69) / 12)); //removed pitch bend
+    frequencyData = clkfrq / float(32 * pitchInHz);
+    if (frequencyData > 1023)
+        return false;
+    SetSquareFrequency(voice, frequencyData);
+    return true;
+}
+
+void SN76489::SetSquareFrequency(uint8_t voice, int frequencyData)
+{
+    if (voice < 0 || voice > 2)
+        return;
+    writeRaw(0x80 | frequencyRegister[voice] | (frequencyData & 0x0f));
+    writeRaw(frequencyData >> 4);
+}
+
+void SN76489::UpdateAttenuation(uint8_t voice)
+{
+    uint8_t attenuationValue;
+    if (voice < 0 || voice > 3) 
+        return;
+    attenuationValue = (127 - currentVelocity[voice]) >> 3;
+    writeRaw(0x80 | attenuationRegister[voice] | attenuationValue);
+}
+
+void SN76489::TestToneOn(bool channelControl[4])
+{
+    for(uint8_t i = 0; i < 3; i++)
+    {
+        if(channelControl[i])
+            SetChannelOn(60, i);
+    }
+    if(channelControl[3]) //noise channel
+        SetNoiseOn(60);
+}
+
+void SN76489::TestToneOff(bool channelControl[4])
+{
+    for(uint8_t i = 0; i < 3; i++)
+    {
+        SetChannelOff(60, i);
+    }
+    SetNoiseOff(60);
+}
+
 SN76489::~SN76489(){}
diff --git a/lib/VGMEngine/SN76489.h b/lib/VGMEngine/SN76489.h
@@ -12,11 +12,27 @@ class SN76489
     void reset();
     void write(uint8_t data);
     void setClock(uint32_t frq);
+    void SetChannelOn(uint8_t key, uint8_t voice);
+    void SetChannelOff(uint8_t key, uint8_t voice);
+    void SetNoiseOn(uint8_t key);
+    void SetNoiseOff(uint8_t key);
+    bool UpdateNoiseControl();
+    void UpdateAttenuation(uint8_t voice);
+    void SetSquareFrequency(uint8_t voice, int frequencyData);
+    void TestToneOn(bool channelControl[4]);
+    void TestToneOff(bool channelControl[4]);
+    bool UpdateSquarePitch(uint8_t voice);
 private:
     //ChipClock* clk;
     uint32_t clkfrq = NTSC_COLORBURST;
     Bus* bus;
     uint8_t WE;
+    const uint8_t attenuationRegister[4] = {0x10, 0x30, 0x50, 0x70};
+    const uint8_t frequencyRegister[3] = {0x00, 0x20, 0x40};
+    uint8_t currentNote[4] = {0, 0, 0, 0};
+    uint8_t currentVelocity[4] = {0, 0, 0, 0};
+    const int noiseCh = 3;
+    const int MAX_CHANNELS_PSG = 3;
     unsigned char psgFrqLowByte = 0;
     void writeRaw(uint8_t data);
 };

diff --git a/lib/VGMEngine/VGMEngine.cpp b/lib/VGMEngine/VGMEngine.cpp
@@ -67,11 +67,36 @@ bool VGMEngineClass::begin(File *f)
     dacSampleCountDown = 0;
     MegaStream_Reset(&stream);
     load();
+    if(isSyncToneEnabled)
+    {
+        playTestTones();
+    }
     state = PLAYING;
     ready = true;
     return true;
 }
 
+void VGMEngineClass::playTestTones()
+{
+    ym2612->SetVoice(testVoice);
+    for(int i = 0; i < 3; i++)
+    {
+        //TODO: SN76489
+        ym2612->TestToneOn(ym2612CHControl);
+        sn76489->TestToneOn(sn76489CHControl);
+        delay(250);
+        ym2612->TestToneOff();
+        sn76489->TestToneOff(sn76489CHControl);
+        delay(250);
+    }
+
+    delay(250);
+
+    sn76489->reset();
+    ym2612->reset();
+}
+
+
 void VGMEngineClass::resetDataBlocks()
 {
     memset(dataBlocks, 0, sizeof(dataBlocks));
@@ -297,7 +322,7 @@ VGMEngineState VGMEngineClass::play()
             {
                 uint8_t data = ram.ReadByte(dacStreamBufPos++);
                 // check if channel 6 is enabled, since this is a DAC write
-                if (ym2612CHControl[0x06])
+                if (ym2612CHControl[0x05])
                 {
                     ym2612->write(0x2A, data, 0);
                 }
@@ -466,7 +491,7 @@ uint16_t VGMEngineClass::parseVGM()
             {
                 uint8_t data = ram.ReadByte(pcmBufferPosition++);
                 // check if channel 6 is enabled, since this is a DAC write
-                if (ym2612CHControl[0x06])
+                if (ym2612CHControl[0x05])
                 {
                     ym2612->write(0x2A, data, 0);
                 }

diff --git a/lib/VGMEngine/VGMEngine.h b/lib/VGMEngine/VGMEngine.h
@@ -68,6 +68,7 @@ class VGMEngineClass
     bool sn76489CHControl[4] = {true, true, true, true};
     //Keeps track of the currently latched channel so we can ignore writes if disabled
     uint8_t sn76489Latched = 0;
+    bool isSyncToneEnabled = false; //Should a test tone at the start of each VGM be played? This is to help people sync individual audio tracks for things like oscilloscope views.
     VGMEngineState state = IDLE;
     bool resetISR = false;
     bool isBusy = false;
@@ -111,6 +112,7 @@ class VGMEngineClass
     void chipSetup();
     bool storePCM(bool skip = false);
     bool topUp();
+    void playTestTones();
     uint16_t parseVGM();
 };
 

diff --git a/lib/VGMEngine/Voice.h b/lib/VGMEngine/Voice.h
@@ -0,0 +1,25 @@
+#ifndef VOICE_H_
+#define VOICE_H_
+
+//OPM File Format https://vgmrips.net/wiki/OPM_File_Format
+typedef struct
+{
+  unsigned char LFO[5];
+  unsigned char CH[7];
+  unsigned char M1[11];
+  unsigned char C1[11];
+  unsigned char M2[11];
+  unsigned char C2[11];
+} Voice;
+
+static const Voice testVoice = (Voice)
+{
+    {0, 0, 0, 0, 0}, //LFO
+    {64, 7, 2, 0, 0, 120, 0}, //CH
+    {26, 8, 5, 2, 2, 32, 3, 3, 3, 0, 0}, //M1
+    {29, 5, 4, 2, 1, 32, 3, 4, 3, 0, 0}, //C1
+    {28, 4, 2, 2, 3, 31, 3, 1, 3, 0, 0}, //M2
+    {31, 10, 3, 1, 1, 12, 3, 1, 3, 0, 0}  //C2
+}; 
+
+#endif