Rework voltage summers

src/Filter.cpp

@@ -27,49 +27,9 @@
 namespace reSIDfp
 {
 
-static constexpr int summerIdx[5] =
-{
-    FilterModelConfig::summer_offset<0>::value,
-    FilterModelConfig::summer_offset<1>::value,
-    FilterModelConfig::summer_offset<2>::value,
-    FilterModelConfig::summer_offset<3>::value,
-    FilterModelConfig::summer_offset<4>::value
-};
-
-static constexpr int mixerIdx[8] =
-{
-    FilterModelConfig::mixer_offset<0>::value,
-    FilterModelConfig::mixer_offset<1>::value,
-    FilterModelConfig::mixer_offset<2>::value,
-    FilterModelConfig::mixer_offset<3>::value,
-    FilterModelConfig::mixer_offset<4>::value,
-    FilterModelConfig::mixer_offset<5>::value,
-    FilterModelConfig::mixer_offset<6>::value,
-    FilterModelConfig::mixer_offset<7>::value
-};
-
 void Filter::updateMixing()
 {
     currentVolume = volume + (vol * (1<<16));
-
-    int Nsum = 0;
-    int Nmix = 0;
-
-    (filt1 ? Nsum : Nmix)++;
-    (filt2 ? Nsum : Nmix)++;
-
-    if (filt3) Nsum++;
-    else if (!voice3off) Nmix++;
-
-    (filtE ? Nsum : Nmix)++;
-
-    currentSummer = summer + summerIdx[Nsum];
-
-    if (lp) Nmix++;
-    if (bp) Nmix++;
-    if (hp) Nmix++;
-
-    currentMixer = mixer + mixerIdx[Nmix];
 }
 
 void Filter::writeFC_LO(uint8_t fc_lo)

src/Filter.h

@@ -51,12 +51,6 @@ class Filter
 
     const Integrator& m_bpIntegrator;
 
-    /// Current filter/voice mixer setting.
-    uint16_t* currentMixer = nullptr;
-
-    /// Filter input summer setting.
-    uint16_t* currentSummer = nullptr;
-
     /// Filter resonance value.
     uint16_t* currentResonance = nullptr;
 
@@ -106,6 +100,17 @@ class Filter
     /// Selects which inputs to route through filter.
     uint8_t filt = 0;
 
+private:
+    inline int32_t getNormalizedVoice(float v, uint8_t env) const
+    {
+        return m_fmc.getNormalizedVoice(v, env);
+    }
+
+    inline int32_t getNormalizedScaledVoice(float v, uint8_t env, float scale) const
+    {
+        return m_fmc.getNormalizedVoice(v*scale, env);
+    }
+
 protected:
     /**
      * Update filter cutoff frequency.
@@ -131,12 +136,11 @@ class Filter
 
     virtual void restartIntegrators() = 0;
 
-    inline int32_t getNormalizedVoice(float v, uint8_t env) const
-    {
-        return m_fmc.getNormalizedVoice(v, env);
-    }
+    virtual float toFilterScale() const  = 0;
+
+    virtual float toMixerScale(bool filter) const  = 0;
 
-    virtual int32_t getNormalizedMixerVoice(float v, uint8_t env) const = 0;
+    virtual float voice3OffScale() const = 0;
 
 public:
     Filter(const FilterModelConfig& fmc,
@@ -227,33 +231,33 @@ uint16_t Filter::clock(Voice& voice1, Voice& voice2, Voice& voice3)
 
     // Voltage summer for filter input
     int32_t Vsum = 0;
-    Vsum += filt1 ? getNormalizedVoice(wav1, env1) : 0;
-    Vsum += filt2 ? getNormalizedVoice(wav2, env2) : 0;
-    Vsum += filt3 ? getNormalizedVoice(wav3, env3) : 0;
-    Vsum += filtE ? getNormalizedVoice(extin, 0) : 0;
+    Vsum += filt1 ? getNormalizedVoice(wav1, env1) : getNormalizedScaledVoice(wav1, env1, toFilterScale());
+    Vsum += filt2 ? getNormalizedVoice(wav2, env2) : getNormalizedScaledVoice(wav2, env2, toFilterScale());
+    Vsum += filt3 ? getNormalizedVoice(wav3, env3) : getNormalizedScaledVoice(wav3, env3, toFilterScale());
+    Vsum += filtE ? getNormalizedVoice(extin,   0) : getNormalizedScaledVoice(extin,   0, toFilterScale());
     Vsum += Vlp;
     Vsum += currentResonance[Vbp];
 
     // Filter
-    Vhp = currentSummer[Vsum];
+    Vhp = summer[Vsum];
     Vbp = m_hpIntegrator.solve(Vhp);
     Vlp = m_bpIntegrator.solve(Vbp);
 
-    int32_t Vfilt = 0;
-    if (lp) Vfilt += Vlp;
-    if (bp) Vfilt += Vbp;
-    if (hp) Vfilt += Vhp;
+    // Voice 3 is silenced by voice3off if it is not routed through the filter.
+    const float v3Scale = voice3off ? voice3OffScale() : 1.f;
 
     // Voltage summer for mixer input
     int32_t Vmix = 0;
-    Vmix += filt1 ? 0 : getNormalizedMixerVoice(wav1, env1);
-    Vmix += filt2 ? 0 : getNormalizedMixerVoice(wav2, env2);
-    // Voice 3 is silenced by voice3off if it is not routed through the filter
-    Vmix += (filt3 || voice3off) ? 0 : getNormalizedMixerVoice(wav3, env3);
-    Vmix += filtE ? 0 : getNormalizedMixerVoice(extin, 0);
-    Vmix += Vfilt;
-
-    return currentVolume[currentMixer[Vmix]];
+    Vmix += getNormalizedScaledVoice(wav1, env1, toMixerScale(filt1));
+    Vmix += getNormalizedScaledVoice(wav2, env2, toMixerScale(filt2));
+    Vmix += getNormalizedScaledVoice(wav3, env3, toMixerScale(filt3) * v3Scale);
+    Vmix += getNormalizedScaledVoice(extin,   0, toMixerScale(filtE));
+    // FIXME
+    Vmix += lp ? Vlp : 32768;
+    Vmix += bp ? Vbp : 32768;
+    Vmix += hp ? Vhp : 32768;
+
+    return currentVolume[mixer[Vmix]];
 }
 
 } // namespace reSIDfp

src/Filter6581.h

@@ -338,15 +338,15 @@ class Filter6581 final : public Filter
 
     void restartIntegrators() override { hpIntegrator.restart(); bpIntegrator.restart(); }
 
-    /*
-     * The filter input resistors on the 6581 are slightly bigger than the voice ones,
-     * scale the values accordingly.
-     */
-    int32_t getNormalizedMixerVoice(float v, uint8_t env) const override
+    constexpr float toFilterScale() const override { return 0.05625f * 0.03f; }
+
+    constexpr float toMixerScale(bool filter) const override
     {
-        return getNormalizedVoice(v * static_cast<float>(FilterModelConfig6581::VF_TR_RATIO), env);
+        return filter ? 0.05625f * 0.045f : static_cast<float>(FilterModelConfig6581::VF_TR_RATIO);
     }
 
+    constexpr float voice3OffScale() const override { return 0.05625f * 2.f; }
+
 public:
     Filter6581() :
         Filter(*FilterModelConfig6581::getInstance(), hpIntegrator, bpIntegrator),

src/Filter8580.h

@@ -295,11 +295,15 @@ class Filter8580 final : public Filter
 
     void restartIntegrators() override { hpIntegrator.restart(); bpIntegrator.restart(); }
 
-    int32_t getNormalizedMixerVoice(float v, uint8_t env) const override
+    constexpr float toFilterScale() const override { return 0.02625f * 0.03f; }
+
+    constexpr float toMixerScale(bool filter) const override
     {
-        return getNormalizedVoice(v, env);
+        return filter ? 0.02625f * 0.045f : 1.f;
     }
 
+    constexpr float voice3OffScale() const override { return 0.02625f * 2.f; }
+
 public:
     Filter8580() :
         Filter(*FilterModelConfig8580::getInstance(), hpIntegrator, bpIntegrator),

src/FilterModelConfig.cpp

@@ -48,8 +48,8 @@ FilterModelConfig::FilterModelConfig(
     norm(1.0 / denorm),
     N16(norm * UINT16_MAX),
     voice_voltage_range(vvr),
-    mixer(new uint16_t[mixer_offset<8>::value]),
-    summer(new uint16_t[summer_offset<5>::value]),
+    mixer(new uint16_t[7 << 16]),
+    summer(new uint16_t[6 << 16]),
     volume(new uint16_t[16 * (1 << 16)]),
     resonance(new uint16_t[16 * (1 << 16)])
 {

src/FilterModelConfig.h

@@ -173,8 +173,7 @@ class FilterModelConfig
     virtual double getVoiceDC(uint8_t env) const = 0;
 
     /**
-     * The filter summer operates at n ~ 1, and has 5 fundamentally different
-     * input configurations (2 - 6 input "resistors").
+     * The filter summer operates at n ~ 1, and has 6 input "resistors".
      *
      * Note that all "on" transistors are modeled as one. This is not
      * entirely accurate, since the input for each transistor is different,
@@ -185,27 +184,22 @@ class FilterModelConfig
     {
         const double r_N16 = 1. / N16;
 
-        int idx = 0;
-        for (int i = 0; i < 5; i++)
-        {
-            const int idiv = 2 + i;        // 2 - 6 input "resistors".
-            const int size = idiv << 16;
-            const double n = idiv;
-            const double r_idiv = 1. / idiv;
-            opampModel.reset();
+        constexpr int idiv = 6;
+        constexpr int size = idiv << 16;
+        const double n = idiv;
+        constexpr double r_idiv = 1. / idiv;
+        opampModel.reset();
 
-            for (int vi = 0; vi < size; vi++)
-            {
-                const double vin = vmin + vi * r_N16 * r_idiv; /* vmin .. vmax */
-                summer[idx++] = getNormalizedValue(opampModel.solve(n, vin));
-            }
+        for (int vi = 0; vi < size; vi++)
+        {
+            const double vin = vmin + vi * r_N16 * r_idiv; /* vmin .. vmax */
+            summer[vi] = getNormalizedValue(opampModel.solve(n, vin));
         }
     }
 
     /**
      * The audio mixer operates at n ~ 8/6 (6581) or 8/5 (8580),
-     * and has 8 fundamentally different input configurations
-     * (0 - 7 input "resistors").
+     * and has 7 input "resistors".
      *
      * All "on", transistors are modeled as one - see comments above for
      * the filter summer.
@@ -214,20 +208,16 @@ class FilterModelConfig
     {
         const double r_N16 = 1. / N16;
 
-        int idx = 0;
-        for (int i = 0; i < 8; i++)
-        {
-            const int idiv = (i == 0) ? 1 : i;
-            const int size = (i == 0) ? 1 : i << 16;
-            const double n = i * nRatio;
-            const double r_idiv = 1. / idiv;
-            opampModel.reset();
+        constexpr int idiv = 7;
+        constexpr int size = idiv << 16;
+        const double n = idiv * nRatio;
+        constexpr double r_idiv = 1. / idiv;
+        opampModel.reset();
 
-            for (int vi = 0; vi < size; vi++)
-            {
-                const double vin = vmin + vi * r_N16 * r_idiv; /* vmin .. vmax */
-                mixer[idx++] = getNormalizedValue(opampModel.solve(n, vin));
-            }
+        for (int vi = 0; vi < size; vi++)
+        {
+            const double vin = vmin + vi * r_N16 * r_idiv; /* vmin .. vmax */
+            mixer[vi] = getNormalizedValue(opampModel.solve(n, vin));
         }
     }