spu: ignore KeyOff events fired right after KeyOn

Fixes Dragon Ball - Final Bout: Title Screen (Track 29)

src/cpu/cpu.cpp

@@ -108,6 +108,7 @@ bool CPU::executeInstructions(int count) {
 
         moveLoadDelaySlots();
 
+        sys->cycles++;
         if (sys->state != System::State::run) return false;
     }
     return true;

src/device/spu/voice.cpp

@@ -90,7 +90,7 @@ void Voice::parseFlags(uint8_t flags) {
         repeatAddress = currentAddress;
     }
 
-        // Jump to Repeat address AFTER playing current sample
+    // Jump to Repeat address AFTER playing current sample
     if (flags & ADPCM::Flag::LoopEnd) {
         loopEnd = true;
         loadRepeatAddress = true;
@@ -103,7 +103,7 @@ void Voice::parseFlags(uint8_t flags) {
     }
 }
 
-void Voice::keyOn() {
+void Voice::keyOn(uint64_t cycles) {
     decodedSamples.clear();
     counter.sample = 0;
     adsrVolume._reg = 0;
@@ -124,9 +124,18 @@ void Voice::keyOn() {
 
     prevSample[0] = prevSample[1] = 0;
     prevDecodedSamples.clear();
+
+    this->cycles = cycles;
 }
 
-void Voice::keyOff() {
+void Voice::keyOff(uint64_t cycles) {
+    // SPU seems to ignore KeyOff events that were fired close to KeyOn.
+    // Value of 384 cycles was picked by listening to Dragon Ball Final Bout - BGM 29
+    // and comparing it to recording from real HW.
+    // It's not verified by any tests for now
+    if (cycles != 0 && cycles - this->cycles < 384) {
+        return;
+    }
     state = Voice::State::Release;
     adsrWaitCycles = 0;
 }

src/device/spu/voice.h

@@ -39,7 +39,8 @@ struct Voice {
 
     float sample;  // Used for Pitch Modulation
 
-    bool enabled;  // Allows for muting individual channels
+    bool enabled;     // Allows for muting individual channels
+    uint64_t cycles;  // For dismissing KeyOff write right after KeyOn
 
     // ADPCM decoding
     int32_t prevSample[2];
@@ -52,8 +53,8 @@ struct Voice {
     void processEnvelope();
     void parseFlags(uint8_t flags);
 
-    void keyOn();
-    void keyOff();
+    void keyOn(uint64_t cycles = 0);
+    void keyOff(uint64_t cycles = 0);
 
     template <class Archive>
     void serialize(Archive& ar) {
@@ -72,6 +73,7 @@ struct Voice {
         ar(loadRepeatAddress);
         ar(flagsParsed);
         ar(sample);
+        ar(cycles);
         ar(prevSample);
         ar(decodedSamples);
         ar(prevDecodedSamples);

src/system.cpp

@@ -34,6 +34,8 @@ System::System() {
 
     debugOutput = config["debug"]["log"]["system"].get<int>();
     biosLog = config["debug"]["log"]["bios"];
+
+    cycles = 0;
 }
 
 // Note: stupid static_casts and asserts are only to suppress MSVC warnings

src/system.h

@@ -64,6 +64,8 @@ struct System {
     bool debugOutput = true;  // Print BIOS logs
     bool biosLoaded = false;
 
+    uint64_t cycles;
+
     // Devices
     std::unique_ptr<mips::CPU> cpu;