ZX beeper: implement overlay drums

1-bit samples up to 2048 bits in length triggered with 17xx

TODO.md

@@ -1,7 +1,6 @@
 # to-do for 0.6pre1
 
 - RF5C68 system
-- ZX beeper system overlay percussion
 - ADPCM chips
 - Game Boy envelope macro/sequence
 - rewrite the system name detection function anyway

src/engine/platform/zxbeeper.cpp

@@ -43,6 +43,25 @@ void DivPlatformZXBeeper::acquire(short* bufL, short* bufR, size_t start, size_t
   for (size_t h=start; h<start+len; h++) {
     // clock here
     bool o=false;
+    if (curSample>=0 && curSample<parent->song.sampleLen) {
+      if (--curSamplePeriod<0) {
+        DivSample* s=parent->getSample(curSample);
+        if (s->samples<=0) {
+          curSample=-1;
+          continue;
+        }
+
+        o=s->data8[curSamplePos++];
+        bufL[h]=o?16384:0;
+        if (curSamplePos>=s->samples) curSample=-1;
+        // 256 bits
+        if (curSamplePos>2047) curSample=-1;
+        
+        curSamplePeriod=15;
+      }
+      continue;
+    }
+
     unsigned short oldPos=chan[curChan].sPosition;
 
     if (sOffTimer) {
@@ -128,9 +147,7 @@ int DivPlatformZXBeeper::dispatch(DivCommand c) {
       break;
     }
     case DIV_CMD_NOTE_OFF:
-      chan[c.chan].dacSample=-1;
       if (dumpWrites) addWrite(0xffff0002+(c.chan<<8),0);
-      chan[c.chan].pcm=false;
       chan[c.chan].active=false;
       chan[c.chan].keyOff=true;
       chan[c.chan].macroInit(NULL);
@@ -190,13 +207,9 @@ int DivPlatformZXBeeper::dispatch(DivCommand c) {
       chan[c.chan].duty=c.value;
       break;
     case DIV_CMD_SAMPLE_MODE:
-      chan[c.chan].pcm=c.value;
-      break;
-    case DIV_CMD_SAMPLE_BANK:
-      sampleBank=c.value;
-      if (sampleBank>(parent->song.sample.size()/12)) {
-        sampleBank=parent->song.sample.size()/12;
-      }
+      curSample=c.value;
+      curSamplePos=0;
+      curSamplePeriod=0;
       break;
     case DIV_CMD_LEGATO:
       chan[c.chan].baseFreq=NOTE_FREQUENCY(c.value+((chan[c.chan].std.arp.will && !chan[c.chan].std.arp.mode)?(chan[c.chan].std.arp.val):(0)));
@@ -265,8 +278,10 @@ void DivPlatformZXBeeper::reset() {
   cycles=0;
   curChan=0;
   sOffTimer=0;
-  sampleBank=0;
   ulaOut=0;
+  curSample=-1;
+  curSamplePos=0;
+  curSamplePeriod=0;
 }
 
 bool DivPlatformZXBeeper::keyOffAffectsArp(int ch) {

src/engine/platform/zxbeeper.h

@@ -27,10 +27,8 @@
 class DivPlatformZXBeeper: public DivDispatch {
   struct Channel {
     int freq, baseFreq, pitch, pitch2, note;
-    int dacPeriod, dacRate;
-    unsigned int dacPos;
-    int dacSample, ins;
-    bool active, insChanged, freqChanged, keyOn, keyOff, inPorta, noise, pcm, furnaceDac;
+    int ins;
+    bool active, insChanged, freqChanged, keyOn, keyOff, inPorta;
     signed char vol, outVol;
     unsigned short sPosition;
     unsigned char duty;
@@ -45,10 +43,6 @@ class DivPlatformZXBeeper: public DivDispatch {
       pitch(0),
       pitch2(0),
       note(0),
-      dacPeriod(0),
-      dacRate(0),
-      dacPos(0),
-      dacSample(-1),
       ins(-1),
       active(false),
       insChanged(true),
@@ -56,9 +50,6 @@ class DivPlatformZXBeeper: public DivDispatch {
       keyOn(false),
       keyOff(false),
       inPorta(false),
-      noise(false),
-      pcm(false),
-      furnaceDac(false),
       vol(1),
       outVol(1),
       sPosition(0),
@@ -75,10 +66,10 @@ class DivPlatformZXBeeper: public DivDispatch {
   std::queue<QueuedWrite> writes;
   unsigned char lastPan, ulaOut;
 
-  int cycles, curChan, sOffTimer, delay;
+  int cycles, curChan, sOffTimer, delay, curSample, curSamplePeriod;
+  unsigned int curSamplePos;
   int tempL[32];
   int tempR[32];
-  unsigned char sampleBank, lfoMode, lfoSpeed;
   unsigned char regPool[128];
   friend void putDispatchChan(void*,int,int);
   public:

src/engine/sysDef.cpp

@@ -1522,7 +1522,21 @@ void DivEngine::registerSystems() {
     {"Channel 1", "Channel 2", "Channel 3", "Channel 4", "Channel 5", "Channel 6"},
     {"CH1", "CH2", "CH3", "CH4", "CH5", "CH6"},
     {DIV_CH_WAVE, DIV_CH_WAVE, DIV_CH_WAVE, DIV_CH_WAVE, DIV_CH_WAVE, DIV_CH_WAVE},
-    {DIV_INS_BEEPER, DIV_INS_BEEPER, DIV_INS_BEEPER, DIV_INS_BEEPER, DIV_INS_BEEPER, DIV_INS_BEEPER}
+    {DIV_INS_BEEPER, DIV_INS_BEEPER, DIV_INS_BEEPER, DIV_INS_BEEPER, DIV_INS_BEEPER, DIV_INS_BEEPER},
+    {},
+    [this](int ch, unsigned char effect, unsigned char effectVal) -> bool {
+      switch (effect) {
+        case 0x12: // pulse width
+          dispatchCmd(DivCommand(DIV_CMD_STD_NOISE_MODE,ch,effectVal));
+          break;
+        case 0x17: // overlay sample
+          dispatchCmd(DivCommand(DIV_CMD_SAMPLE_MODE,ch,effectVal));
+          break;
+        default:
+          return false;
+      }
+      return true;
+    }
   );
 
   sysDefs[DIV_SYSTEM_YM2612_EXT]=new DivSysDef(