2023-08-16 16:54:12 -04:00
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/*
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* This file is part of libsidplayfp, a SID player engine.
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*
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* Copyright 2014-2016 Leandro Nini <drfiemost@users.sourceforge.net>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*/
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#include "Integrator8580.h"
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2024-11-27 01:18:06 -05:00
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namespace reSIDfp
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{
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int Integrator8580::solve(int vi) const
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{
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// Make sure we're not in subthreshold mode
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assert(vx < nVgt);
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// DAC voltages
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const unsigned int Vgst = nVgt - vx;
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const unsigned int Vgdt = (vi < nVgt) ? nVgt - vi : 0; // triode/saturation mode
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const unsigned int Vgst_2 = Vgst * Vgst;
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const unsigned int Vgdt_2 = Vgdt * Vgdt;
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// DAC current, scaled by (1/m)*2^13*m*2^16*m*2^16*2^-15 = m*2^30
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const int n_I_dac = n_dac * (static_cast<int>(Vgst_2 - Vgdt_2) >> 15);
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// Change in capacitor charge.
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vc += n_I_dac;
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// vx = g(vc)
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const int tmp = (vc >> 15) + (1 << 15);
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assert(tmp < (1 << 16));
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vx = fmc.getOpampRev(tmp);
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// Return vo.
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return vx - (vc >> 14);
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}
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} // namespace reSIDfp
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