Update residfp to newer build

Co-Authored-By: Alexander Babikov <2708460+lemondrops@users.noreply.github.com>

src/sound/resid-fp/Dac.cpp

@@ -0,0 +1,123 @@
+/*
+ * This file is part of libsidplayfp, a SID player engine.
+ *
+ * Copyright 2011-2016 Leandro Nini <drfiemost@users.sourceforge.net>
+ * Copyright 2007-2010 Antti Lankila
+ * Copyright 2004,2010 Dag Lem <resid@nimrod.no>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+
+#include "Dac.h"
+
+namespace reSIDfp
+{
+
+Dac::Dac(unsigned int bits) :
+    dac(new double[bits]),
+    dacLength(bits)
+{}
+
+Dac::~Dac()
+{
+    delete [] dac;
+}
+
+double Dac::getOutput(unsigned int input) const
+{
+    double dacValue = 0.;
+
+    for (unsigned int i = 0; i < dacLength; i++)
+    {
+        if ((input & (1 << i)) != 0)
+        {
+            dacValue += dac[i];
+        }
+    }
+
+    return dacValue;
+}
+
+void Dac::kinkedDac(ChipModel chipModel)
+{
+    const double R_INFINITY = 1e6;
+
+    // Non-linearity parameter, 8580 DACs are perfectly linear
+    const double _2R_div_R = chipModel == MOS6581 ? 2.20 : 2.00;
+
+    // 6581 DACs are not terminated by a 2R resistor
+    const bool term = chipModel == MOS8580;
+
+    // Calculate voltage contribution by each individual bit in the R-2R ladder.
+    for (unsigned int set_bit = 0; set_bit < dacLength; set_bit++)
+    {
+        double Vn = 1.;                   // Normalized bit voltage.
+        double R = 1.;                    // Normalized R
+        const double _2R = _2R_div_R * R; // 2R
+        double Rn = term ?                // Rn = 2R for correct termination,
+                    _2R : R_INFINITY;     // INFINITY for missing termination.
+
+        unsigned int bit;
+
+        // Calculate DAC "tail" resistance by repeated parallel substitution.
+        for (bit = 0; bit < set_bit; bit++)
+        {
+            Rn = (Rn == R_INFINITY) ?
+                 R + _2R :
+                 R + (_2R * Rn) / (_2R + Rn); // R + 2R || Rn
+        }
+
+        // Source transformation for bit voltage.
+        if (Rn == R_INFINITY)
+        {
+            Rn = _2R;
+        }
+        else
+        {
+            Rn = (_2R * Rn) / (_2R + Rn); // 2R || Rn
+            Vn = Vn * Rn / _2R;
+        }
+
+        // Calculate DAC output voltage by repeated source transformation from
+        // the "tail".
+
+        for (++bit; bit < dacLength; bit++)
+        {
+            Rn += R;
+            const double I = Vn / Rn;
+            Rn = (_2R * Rn) / (_2R + Rn); // 2R || Rn
+            Vn = Rn * I;
+        }
+
+        dac[set_bit] = Vn;
+    }
+
+    // Normalize to integerish behavior
+    double Vsum = 0.;
+
+    for (unsigned int i = 0; i < dacLength; i++)
+    {
+        Vsum += dac[i];
+    }
+
+    Vsum /= 1 << dacLength;
+
+    for (unsigned int i = 0; i < dacLength; i++)
+    {
+        dac[i] /= Vsum;
+    }
+}
+
+} // namespace reSIDfp