VIC-20: add an option to disable filters

src/engine/platform/sound/vic20sound.c

@@ -92,6 +92,7 @@ int vic_sound_machine_calculate_samples(sound_vic20_t *snd, int16_t *pbuf, int n
     int s = 0;
     int i;
     float o;
+    float v;
     int16_t vicbuf;
     int samples_to_do;
 
@@ -100,9 +101,14 @@ int vic_sound_machine_calculate_samples(sound_vic20_t *snd, int16_t *pbuf, int n
         snd->leftover_cycles += samples_to_do - snd->cycles_per_sample;
         vic_sound_clock(snd, samples_to_do);
 
+        v = voltagefunction[(((snd->accum * 7) / snd->accum_cycles) + 1) * snd->volume];
+        if (snd->filter_off) {
+            o = v;
+        } else {
             o = snd->lowpassbuf - snd->highpassbuf;
             snd->highpassbuf += snd->highpassbeta * (snd->lowpassbuf - snd->highpassbuf);
-        snd->lowpassbuf += snd->lowpassbeta * (voltagefunction[(((snd->accum * 7) / snd->accum_cycles) + 1) * snd->volume] - snd->lowpassbuf);
+            snd->lowpassbuf += snd->lowpassbeta * (v - snd->lowpassbuf);
+        }
 
         if (o < -32768) {
             vicbuf = -32768;
@@ -202,7 +208,7 @@ void vic_sound_machine_store(sound_vic20_t *snd, uint16_t addr, uint8_t value)
     }
 }
 
-int vic_sound_machine_init(sound_vic20_t *snd, int speed, int cycles_per_sec)
+int vic_sound_machine_init(sound_vic20_t *snd, int speed, int cycles_per_sec, bool filter_off)
 {
     uint32_t i;
     float dt;
@@ -214,6 +220,7 @@ int vic_sound_machine_init(sound_vic20_t *snd, int speed, int cycles_per_sec)
 
     snd->lowpassbuf = 0.0f;
     snd->highpassbuf = 0.0f;
+    snd->filter_off = filter_off;
 
     snd->speed = speed;
 

src/engine/platform/sound/vic20sound.h

@@ -32,6 +32,7 @@ extern "C" {
 #endif
 
 #include <stdint.h>
+#include <stdbool.h>
 
 struct sound_vic20_s {
     unsigned char div;
@@ -56,13 +57,14 @@ struct sound_vic20_s {
     float highpassbeta;
     float lowpassbuf;
     float lowpassbeta;
+    bool filter_off;
 
     uint16_t noise_LFSR;
     uint8_t noise_LFSR0_old;
 };
 typedef struct sound_vic20_s sound_vic20_t;
 
-int vic_sound_machine_init(sound_vic20_t *snd, int speed, int cycles_per_sec);
+int vic_sound_machine_init(sound_vic20_t *snd, int speed, int cycles_per_sec, bool filter_off);
 void vic_sound_machine_store(sound_vic20_t *snd, uint16_t addr, uint8_t value);
 int vic_sound_machine_calculate_samples(sound_vic20_t *snd, int16_t *pbuf, int nr, int soc, int scc, uint32_t delta_t);
 void vic_sound_clock(sound_vic20_t *snd, uint32_t cycles);

src/engine/platform/vic20.cpp

@@ -317,7 +317,7 @@ void DivPlatformVIC20::reset() {
     chan[i]=Channel();
     chan[i].std.setEngine(parent);
   }
-  vic_sound_machine_init(vic,rate,chipClock);
+  vic_sound_machine_init(vic,rate,chipClock,filterOff);
   hasWaveWrite=false;
   rWrite(14,15);
   // hack: starting noise channel right away after this would result in a dead
@@ -336,6 +336,7 @@ void DivPlatformVIC20::notifyInsDeletion(void* ins) {
 }
 
 void DivPlatformVIC20::setFlags(const DivConfig& flags) {
+  filterOff=flags.getBool("filterOff",false);
   if (flags.getInt("clockSel",0)) {
     chipClock=COLOR_PAL/4.0;
   } else {

src/engine/platform/vic20.h

@@ -37,6 +37,7 @@ class DivPlatformVIC20: public DivDispatch {
   DivDispatchOscBuffer* oscBuf[4];
   bool isMuted[4];
   bool hasWaveWrite;
+  bool filterOff;
 
   unsigned char regPool[16];
   sound_vic20_t* vic;

src/gui/sysConf.cpp

@@ -2612,6 +2612,25 @@ bool FurnaceGUI::drawSysConf(int chan, int sysPos, DivSystem type, DivConfig& fl
       }
       break;
     }
+    case DIV_SYSTEM_VIC20: {
+      bool sysPal=flags.getInt("clockSel",0);
+      bool filterOff=flags.getBool("filterOff",false);
+
+      if (ImGui::Checkbox(_("PAL"),&sysPal)) {
+        altered=true;
+      }
+      if (ImGui::Checkbox(_("Disable filtering"),&filterOff)) {
+        altered=true;
+      }
+
+      if (altered) {
+        e->lockSave([&]() {
+          flags.set("clockSel",(int)sysPal);
+          flags.set("filterOff",filterOff);
+        });
+      }
+      break;
+    }
     case DIV_SYSTEM_SWAN:
     case DIV_SYSTEM_BUBSYS_WSG:
     case DIV_SYSTEM_PET: