changes to sample rate storage

as of now we store and use the actual sample rate as opposed to an index
fo a fixed rate table.

this allows for more flexibility in a future file format...

src/engine/engine.cpp

@@ -926,11 +926,11 @@ bool DivEngine::load(unsigned char* f, size_t slen) {
       }
       logD("%d name %s (%d)\n",i,sample->name.c_str(),sample->length);
       if (ds.version<0x0b) {
-        sample->rate=4;
+        sample->rate=22050;
         sample->pitch=0;
         sample->vol=0;
       } else {
-        sample->rate=reader.readC();
+        sample->rate=fileToDivRate(reader.readC());
         sample->pitch=reader.readC();
         sample->vol=reader.readC();
       }
@@ -1127,7 +1127,7 @@ SafeWriter* DivEngine::save() {
   for (DivSample* i: song.sample) {
     w->writeI(i->length);
     w->writeString(i->name,true);
-    w->writeC(i->rate);
+    w->writeC(divToFileRate(i->rate));
     w->writeC(i->pitch);
     w->writeC(i->vol);
     w->writeC(i->depth);
@@ -1549,6 +1549,48 @@ const int sampleRates[6]={
   4000, 8000, 11025, 16000, 22050, 32000
 };
 
+int DivEngine::fileToDivRate(int frate) {
+  if (frate<0) frate=0;
+  if (frate>5) frate=5;
+  return sampleRates[frate];
+}
+
+int DivEngine::divToFileRate(int drate) {
+  if (drate>26000) {
+    return 5;
+  } else if (drate>18000) {
+    return 4;
+  } else if (drate>14000) {
+    return 3;
+  } else if (drate>9500) {
+    return 2;
+  } else if (drate>6000) {
+    return 1;
+  } else {
+    return 0;
+  }
+  return 4;
+}
+
+int DivEngine::getEffectiveSampleRate(int rate) {
+  if (rate<1) return 0;
+  switch (song.system) {
+    case DIV_SYSTEM_YMU759:
+      return 8000;
+    case DIV_SYSTEM_GENESIS: case DIV_SYSTEM_GENESIS_EXT:
+      return 1278409/(1280000/rate);
+    case DIV_SYSTEM_PCE:
+      return 1789773/(1789773/rate);
+    case DIV_SYSTEM_ARCADE:
+      return (31250*MIN(255,(rate*255/31250)))/255;
+    case DIV_SYSTEM_YM2610: case DIV_SYSTEM_YM2610_EXT:
+      return 18518;
+    default:
+      break;
+  }
+  return rate;
+}
+
 void DivEngine::previewSample(int sample) {
   isBusy.lock();
   if (sample<0 || sample>(int)song.sample.size()) {
@@ -1558,7 +1600,7 @@ void DivEngine::previewSample(int sample) {
     return;
   }
   blip_clear(bb[2]);
-  blip_set_rates(bb[2],sampleRates[song.sample[sample]->rate],got.rate);
+  blip_set_rates(bb[2],song.sample[sample]->rate,got.rate);
   prevSample[2]=0;
   sPreview.pos=0;
   sPreview.sample=sample;
@@ -1772,20 +1814,9 @@ bool DivEngine::addSampleFromFile(const char* path) {
     sample->data[index++]=averaged^(((si.format&SF_FORMAT_SUBMASK)==SF_FORMAT_PCM_U8)?0x8000:0);
   }
   delete[] buf;
-  // 4000, 8000, 11025, 16000, 22050, 32000
-  if (si.samplerate>26000) {
-    sample->rate=5;
-  } else if (si.samplerate>18000) {
-    sample->rate=4;
-  } else if (si.samplerate>14000) {
-    sample->rate=3;
-  } else if (si.samplerate>9500) {
-    sample->rate=2;
-  } else if (si.samplerate>6000) {
-    sample->rate=1;
-  } else {
-    sample->rate=0;
-  }
+  sample->rate=si.samplerate;
+  if (sample->rate<4000) sample->rate=4000;
+  if (sample->rate>32000) sample->rate=32000;
 
   song.sample.push_back(sample);
   song.sampleLen=sampleCount+1;

src/engine/engine.h

@@ -184,6 +184,13 @@ class DivEngine {
 
     // get sys name
     const char* getSystemName(DivSystem sys);
+    
+    // convert sample rate format
+    int fileToDivRate(int frate);
+    int divToFileRate(int drate);
+
+    // get effective sample rate
+    int getEffectiveSampleRate(int rate);
 
     // is FM system
     bool isFMSystem(DivSystem sys);

src/engine/platform/arcade.cpp

@@ -9,9 +9,6 @@ static unsigned short chanOffs[8]={
 static unsigned short opOffs[4]={
   0x00, 0x08, 0x10, 0x18
 };
-static int pcmRates[6]={
-  65,65,90,131,180,255
-};
 static bool isOutput[8][4]={
   // 1     3     2    4
   {false,false,false,true},
@@ -217,7 +214,7 @@ int DivPlatformArcade::dispatch(DivCommand c) {
           break;
         }
         chan[c.chan].pcm.pos=0;
-        chan[c.chan].pcm.freq=pcmRates[parent->song.sample[chan[c.chan].pcm.sample]->rate];
+        chan[c.chan].pcm.freq=MIN(255,(parent->song.sample[chan[c.chan].pcm.sample]->rate*255)/31250);
         break;
       }
       DivInstrument* ins=parent->getIns(chan[c.chan].ins);

src/engine/platform/genesis.cpp

@@ -5,9 +5,6 @@
 
 #include "genesisshared.h"
 
-static int dacRates[6]={
-  160,160,116,80,58,40
-};
 static unsigned char konOffs[6]={
   0, 1, 2, 4, 5, 6
 };
@@ -179,7 +176,7 @@ int DivPlatformGenesis::dispatch(DivCommand c) {
         }
         dacPos=0;
         dacPeriod=0;
-        dacRate=dacRates[parent->song.sample[dacSample]->rate];
+        dacRate=1280000/parent->song.sample[dacSample]->rate;
         break;
       }
       DivInstrument* ins=parent->getIns(chan[c.chan].ins);

src/engine/platform/nes.cpp

@@ -37,10 +37,6 @@ void DivPlatformNES::acquire(short* bufL, short* bufR, size_t start, size_t len)
   }
 }
 
-static int dacRates[6]={
-  4000, 8000, 11025, 16000, 22050, 32000
-};
-
 static unsigned char noiseTable[256]={
   6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 5, 4,
   15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4,
@@ -170,7 +166,7 @@ int DivPlatformNES::dispatch(DivCommand c) {
         }
         dacPos=0;
         dacPeriod=0;
-        dacRate=dacRates[parent->song.sample[dacSample]->rate];
+        dacRate=parent->song.sample[dacSample]->rate;
         break;
       } else if (c.chan==3) { // noise
         chan[c.chan].baseFreq=c.value;

src/engine/platform/pce.cpp

@@ -76,10 +76,6 @@ static unsigned char noiseFreq[12]={
   4,13,15,18,21,23,25,27,29,31,0,2  
 };
 
-static int dacRates[6]={
-  224,224,162,112,81,56
-};
-
 void DivPlatformPCE::tick() {
   for (int i=0; i<6; i++) {
     chan[i].std.next();
@@ -149,7 +145,7 @@ int DivPlatformPCE::dispatch(DivCommand c) {
         }
         chan[c.chan].dacPos=0;
         chan[c.chan].dacPeriod=0;
-        chan[c.chan].dacRate=dacRates[parent->song.sample[chan[c.chan].dacSample]->rate];
+        chan[c.chan].dacRate=1789773/parent->song.sample[chan[c.chan].dacSample]->rate;
         break;
       }
       chan[c.chan].baseFreq=round(FREQ_BASE/pow(2.0f,((float)c.value/12.0f)));

src/engine/sample.cpp

@@ -3,10 +3,6 @@
 #include <string.h>
 #include <sndfile.h>
 
-const int sampleRates[6]={
-  4000, 8000, 11025, 16000, 22050, 32000
-};
-
 bool DivSample::save(const char* path) {
   SNDFILE* f;
   SF_INFO si;
@@ -15,7 +11,7 @@ bool DivSample::save(const char* path) {
   if (length<1) return false;
 
   si.channels=1;
-  si.samplerate=sampleRates[rate];
+  si.samplerate=rate;
   if (depth==16) {
     si.format=SF_FORMAT_PCM_16|SF_FORMAT_WAV;
   } else {

src/engine/sample.h

@@ -14,7 +14,7 @@ struct DivSample {
   DivSample():
     name(""),
     length(0),
-    rate(0),
+    rate(32000),
     vol(0),
     pitch(0),
     depth(16),

src/gui/gui.cpp

@@ -92,10 +92,6 @@ const char* noteNames[120]={
   "C-9", "C#9", "D-9", "D#9", "E-9", "F-9", "F#9", "G-9", "G#9", "A-9", "A#9", "B-9"
 };
 
-const char* rateLabel[6]={
-  "4000Hz", "8000Hz", "11025Hz", "16000Hz", "22050Hz", "32000Hz"
-};
-
 const char* pitchLabel[11]={
   "1/6", "1/5", "1/4", "1/3", "1/2", "1x", "2x", "3x", "4x", "5x", "6x"
 };
@@ -941,10 +937,11 @@ void FurnaceGUI::drawSampleEdit() {
     } else {
       DivSample* sample=e->song.sample[curSample];
       ImGui::InputText("Name",&sample->name);
-      if (ImGui::SliderInt("Rate",&sample->rate,0,5,rateLabel[sample->rate])) {
-        if (sample->rate<0) sample->rate=0;
-        if (sample->rate>5) sample->rate=5;
+      if (ImGui::SliderInt("Rate",&sample->rate,4000,32000,"%dHz")) {
+        if (sample->rate<4000) sample->rate=4000;
+        if (sample->rate>32000) sample->rate=32000;
       }
+      ImGui::Text("effective rate: %dHz",e->getEffectiveSampleRate(sample->rate));
       if (ImGui::SliderScalar("Volume",ImGuiDataType_S8,&sample->vol,&_ZERO,&_ONE_HUNDRED,fmt::sprintf("%d%%%%",sample->vol*2).c_str())) {
         if (sample->vol<0) sample->vol=0;
         if (sample->vol>100) sample->vol=100;