swan: Add command to change internal speaker loudness

doc/7-systems/wonderswan.md

@@ -20,6 +20,11 @@ it has 4 wavetable channels. some of them have additional capabilities:
 - `13xx`: **setup sweep amount.** channel 3 only.
   - `00` to `7F` for 0 to 127.
   - `80` to `FF` for -128 to -1.
+- `20xx`: **set internal speaker loudness.**
+  - 0-1: 100% (default).
+  - 2-3: 200%.
+  - 4-7: 400%.
+  - 8: 800%.
 
 ## info
 

src/engine/dispatch.h

@@ -171,8 +171,9 @@ enum DivDispatchCmds {
   DIV_CMD_X1_010_AUTO_ENVELOPE,
   DIV_CMD_X1_010_SAMPLE_BANK_SLOT,
 
-  DIV_CMD_WS_SWEEP_TIME,
+  DIV_CMD_WS_SWEEP_TIME, // (time)
-  DIV_CMD_WS_SWEEP_AMOUNT,
+  DIV_CMD_WS_SWEEP_AMOUNT, // (value)
+  DIV_CMD_WS_GLOBAL_SPEAKER_VOLUME, // (multiplier)
 
   DIV_CMD_N163_WAVE_POSITION,
   DIV_CMD_N163_WAVE_LENGTH,

src/engine/platform/swan.cpp

@@ -421,6 +421,17 @@ int DivPlatformSwan::dispatch(DivCommand c) {
         rWrite(0x0c,c.value&0xff);
       }
       break;
+    case DIV_CMD_WS_GLOBAL_SPEAKER_VOLUME:
+      if (c.value <= 1) {
+        rWrite(0x11,0x09|(3<<1));
+      } else if (c.value <= 3) {
+        rWrite(0x11,0x09|(2<<1));
+      } else if (c.value <= 7) {
+        rWrite(0x11,0x09|(1<<1));
+      } else {
+        rWrite(0x11,0x09|(0<<1));
+      }
+      break;
     case DIV_CMD_NOTE_PORTA: {
       int destFreq=NOTE_PERIODIC(c.value2+chan[c.chan].sampleNoteDelta);
       bool return2=false;
@@ -631,7 +642,7 @@ void DivPlatformSwan::setFlags(const DivConfig& flags) {
   chipClock=3072000;
   CHECK_CUSTOM_CLOCK;
   rate=chipClock/128;
-  stereo=flags.getBool("stereo",false);
+  stereo=flags.getBool("stereo",true);
   for (int i=0; i<4; i++) {
     oscBuf[i]->setRate(rate);
   }

src/engine/playback.cpp

@@ -170,6 +170,7 @@ const char* cmdName[]={
 
   "WS_SWEEP_TIME",
   "WS_SWEEP_AMOUNT",
+  "WS_GLOBAL_SPEAKER_VOLUME",
 
   "N163_WAVE_POSITION",
   "N163_WAVE_LENGTH",

src/engine/sysDef.cpp

@@ -1389,6 +1389,9 @@ void DivEngine::registerSystems() {
       {0x12, {DIV_CMD_WS_SWEEP_TIME, _("12xx: Setup sweep period (0: disabled; 1-20: enabled/period)")}},
       {0x13, {DIV_CMD_WS_SWEEP_AMOUNT, _("13xx: Set sweep amount")}},
       {0x17, {DIV_CMD_SAMPLE_MODE, _("17xx: Toggle PCM mode (LEGACY)")}},
+    },
+    {
+      {0x20, {DIV_CMD_WS_GLOBAL_SPEAKER_VOLUME, _("20xx: Set internal speaker loudness (0-1: 100%, 2-3: 200%, 4-7: 400%, 8: 800%)")}},
     }
   );