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/*
* This file is part of libsidplayfp, a SID player engine.
*
* Copyright 2011-2016 Leandro Nini <drfiemost@users.sourceforge.net>
* Copyright 2007-2010 Antti Lankila
*
* 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 "WaveformCalculator.h"
#include <cmath>
namespace reSIDfp
{
WaveformCalculator* WaveformCalculator::getInstance()
{
static WaveformCalculator instance;
return &instance;
}
/**
* Parameters derived with the Monte Carlo method based on
* samplings by kevtris. Code and data available in the project repository [1].
*
* The score here reported is the acoustic error
* calculated XORing the estimated and the sampled values.
* In parentheses the number of mispredicted bits
* on a total of 32768.
*
* [1] https://github.com/libsidplayfp/combined-waveforms
*/
const CombinedWaveformConfig config[2][4] =
{
{ /* kevtris chip G (6581 R2) */
{0.90251f, 0.f, 0.f, 1.9147f, 1.6747f, 0.62376f }, // error 1689 (280)
{0.93088f, 2.4843f, 0.f, 1.0353f, 1.1484f, 0.f }, // error 6128 (130)
{0.90988f, 2.26303f, 1.13126f, 1.0035f, 1.13801f, 0.f }, // error 14243 (632)
{0.91f, 1.192f, 0.f, 1.0169f, 1.2f, 0.637f }, // error 64 (2)
},
{ /* kevtris chip V (8580 R5) */
{0.9632f, 0.f, 0.975f, 1.7467f, 2.36132f, 0.975395f}, // error 1380 (169)
{0.92886f, 1.67696f, 0.f, 1.1014f, 1.4352f, 0.f }, // error 8007 (218)
{0.94043f, 1.7937f, 0.981f, 1.1213f, 1.4259f, 0.f }, // error 11957 (362)
{0.96211f, 0.98695f, 1.00387f, 1.46499f, 1.98375f, 0.77777f }, // error 2369 (89)
},
};
/**
* Generate bitstate based on emulation of combined waves.
*
* @param config model parameters matrix
* @param waveform the waveform to emulate, 1 .. 7
* @param accumulator the high bits of the accumulator value
*/
short calculateCombinedWaveform(const CombinedWaveformConfig& config, int waveform, int accumulator)
{
float o[12];
// Saw
for (unsigned int i = 0; i < 12; i++)
{
o[i] = (accumulator & (1 << i)) != 0 ? 1.f : 0.f;
}
// convert to Triangle
if ((waveform & 3) == 1)
{
const bool top = (accumulator & 0x800) != 0;
for (int i = 11; i > 0; i--)
{
o[i] = top ? 1.0f - o[i - 1] : o[i - 1];
}
o[0] = 0.f;
}
// or to Saw+Triangle
else if ((waveform & 3) == 3)
{
// bottom bit is grounded via T waveform selector
o[0] *= config.stmix;
for (int i = 1; i < 12; i++)
{
/*
* Enabling the S waveform pulls the XOR circuit selector transistor down
* (which would normally make the descending ramp of the triangle waveform),
* so ST does not actually have a sawtooth and triangle waveform combined,
* but merely combines two sawtooths, one rising double the speed the other.
*
* http://www.lemon64.com/forum/viewtopic.php?t=25442&postdays=0&postorder=asc&start=165
*/
o[i] = o[i - 1] * (1.f - config.stmix) + o[i] * config.stmix;
}
}
// topbit for Saw
if ((waveform & 2) == 2)
{
o[11] *= config.topbit;
}
// ST, P* waveforms
if (waveform == 3 || waveform > 4)
{
float distancetable[12 * 2 + 1];
distancetable[12] = 1.f;
for (int i = 12; i > 0; i--)
{
distancetable[12-i] = 1.0f / powf(config.distance1, static_cast<float>(i)); // all floats
distancetable[12+i] = 1.0f / powf(config.distance2, static_cast<float>(i)); // all floats
}
float tmp[12];
for (int i = 0; i < 12; i++)
{
float avg = 0.f;
float n = 0.f;
for (int j = 0; j < 12; j++)
{
const float weight = distancetable[i - j + 12];
avg += o[j] * weight;
n += weight;
}
// pulse control bit
if (waveform > 4)
{
const float weight = distancetable[i - 12 + 12];
avg += config.pulsestrength * weight;
n += weight;
}
tmp[i] = (o[i] + avg / n) * 0.5f;
}
for (int i = 0; i < 12; i++)
{
o[i] = tmp[i];
}
}
short value = 0;
for (unsigned int i = 0; i < 12; i++)
{
if (o[i] > config.bias)
{
value |= 1 << i;
}
}
return value;
}
matrix_t* WaveformCalculator::buildTable(ChipModel model)
{
const CombinedWaveformConfig* cfgArray = config[model == MOS6581 ? 0 : 1];
cw_cache_t::iterator lb = CACHE.lower_bound(cfgArray);
if (lb != CACHE.end() && !(CACHE.key_comp()(cfgArray, lb->first)))
{
return &(lb->second);
}
matrix_t wftable(8, 4096);
for (unsigned int idx = 0; idx < 1 << 12; idx++)
{
wftable[0][idx] = 0xfff;
wftable[1][idx] = static_cast<short>((idx & 0x800) == 0 ? idx << 1 : (idx ^ 0xfff) << 1);
wftable[2][idx] = static_cast<short>(idx);
wftable[3][idx] = calculateCombinedWaveform(cfgArray[0], 3, idx);
wftable[4][idx] = 0xfff;
wftable[5][idx] = calculateCombinedWaveform(cfgArray[1], 5, idx);
wftable[6][idx] = calculateCombinedWaveform(cfgArray[2], 6, idx);
wftable[7][idx] = calculateCombinedWaveform(cfgArray[3], 7, idx);
}
#ifdef HAVE_CXX11
return &(CACHE.emplace_hint(lb, cw_cache_t::value_type(cfgArray, wftable))->second);
#else
return &(CACHE.insert(lb, cw_cache_t::value_type(cfgArray, wftable))->second);
#endif
}
} // namespace reSIDfp
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