366 lines
8 KiB
C++
366 lines
8 KiB
C++
// T6W28_Snd_Emu
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#include "T6W28_Apu.h"
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#include <stdlib.h>
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#include <assert.h>
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#undef require
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#define require( expr ) if (! (expr) ) return;
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/* Copyright (C) 2003-2006 Shay Green. This module is free software; you
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can redistribute it and/or modify it under the terms of the GNU Lesser
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General Public License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version. This
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module is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for
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more details. You should have received a copy of the GNU Lesser General
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Public License along with this module; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
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// T6W28_Osc
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namespace MDFN_IEN_NGP
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{
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void fakeBufOffset(int time, int delta, Fake_Buffer* buf) {
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buf->curValue+=delta;
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}
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T6W28_Osc::T6W28_Osc()
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{
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outputs [0] = NULL; // always stays NULL
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outputs [1] = NULL;
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outputs [2] = NULL;
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outputs [3] = NULL;
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}
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void T6W28_Osc::reset()
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{
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delay = 0;
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last_amp_left = 0;
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last_amp_right = 0;
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volume_left = 0;
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volume_right = 0;
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}
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// T6W28_Square
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void T6W28_Square::reset()
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{
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period = 0;
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phase = 0;
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T6W28_Osc::reset();
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}
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void T6W28_Square::run( sms_time_t time, sms_time_t end_time )
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{
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if ((!volume_left && !volume_right) || period <= 128 )
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{
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// ignore 16kHz and higher
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if ( last_amp_left )
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{
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fakeBufOffset( time, -last_amp_left, outputs[2] );
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last_amp_left = 0;
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}
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if ( last_amp_right )
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{
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fakeBufOffset( time, -last_amp_right, outputs[1] );
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last_amp_right = 0;
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}
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time += delay;
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if ( !period )
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{
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time = end_time;
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}
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else if ( time < end_time )
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{
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// keep calculating phase
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int count = (end_time - time + period - 1) / period;
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phase = (phase + count) & 1;
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time += count * period;
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}
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}
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else
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{
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int amp_left = phase ? volume_left : -volume_left;
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int amp_right = phase ? volume_right : -volume_right;
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{
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int delta_left = amp_left - last_amp_left;
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int delta_right = amp_right - last_amp_right;
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if ( delta_left )
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{
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last_amp_left = amp_left;
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fakeBufOffset( time, delta_left, outputs[2] );
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}
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if ( delta_right )
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{
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last_amp_right = amp_right;
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fakeBufOffset( time, delta_right, outputs[1] );
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}
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}
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time += delay;
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if ( time < end_time )
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{
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Fake_Buffer* const output_left = this->outputs[2];
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Fake_Buffer* const output_right = this->outputs[1];
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int delta_left = amp_left * 2;
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int delta_right = amp_right * 2;
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do
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{
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delta_left = -delta_left;
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delta_right = -delta_right;
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fakeBufOffset( time, delta_left, output_left );
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fakeBufOffset( time, delta_right, output_right );
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time += period;
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phase ^= 1;
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}
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while ( time < end_time );
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this->last_amp_left = phase ? volume_left : -volume_left;
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this->last_amp_right = phase ? volume_right : -volume_right;
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}
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}
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delay = time - end_time;
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}
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// T6W28_Noise
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static const int noise_periods [3] = { 0x100, 0x200, 0x400 };
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void T6W28_Noise::reset()
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{
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period = &noise_periods [0];
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shifter = 0x4000;
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tap = 13;
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period_extra = 0;
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T6W28_Osc::reset();
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}
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void T6W28_Noise::run( sms_time_t time, sms_time_t end_time )
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{
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int amp_left = volume_left;
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int amp_right = volume_right;
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if ( shifter & 1 )
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{
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amp_left = -amp_left;
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amp_right = -amp_right;
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}
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{
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int delta_left = amp_left - last_amp_left;
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int delta_right = amp_right - last_amp_right;
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if ( delta_left )
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{
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last_amp_left = amp_left;
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fakeBufOffset( time, delta_left, outputs[2] );
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}
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if ( delta_right )
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{
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last_amp_right = amp_right;
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fakeBufOffset( time, delta_right, outputs[1] );
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}
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}
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time += delay;
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if ( !volume_left && !volume_right )
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time = end_time;
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if ( time < end_time )
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{
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Fake_Buffer* const output_left = this->outputs[2];
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Fake_Buffer* const output_right = this->outputs[1];
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unsigned l_shifter = this->shifter;
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int delta_left = amp_left * 2;
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int delta_right = amp_right * 2;
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int l_period = *this->period * 2;
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if ( !l_period )
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l_period = 16;
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do
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{
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int changed = (l_shifter + 1) & 2; // set if prev and next bits differ
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l_shifter = (((l_shifter << 14) ^ (l_shifter << tap)) & 0x4000) | (l_shifter >> 1);
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if ( changed )
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{
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delta_left = -delta_left;
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fakeBufOffset( time, delta_left, output_left );
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delta_right = -delta_right;
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fakeBufOffset( time, delta_right, output_right );
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}
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time += l_period;
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}
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while ( time < end_time );
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this->shifter = l_shifter;
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this->last_amp_left = delta_left >> 1;
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this->last_amp_right = delta_right >> 1;
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}
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delay = time - end_time;
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}
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// T6W28_Apu
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T6W28_Apu::T6W28_Apu()
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{
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for ( int i = 0; i < 3; i++ )
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{
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oscs [i] = &squares [i];
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}
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oscs [3] = &noise;
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reset();
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}
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T6W28_Apu::~T6W28_Apu()
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{
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}
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void T6W28_Apu::osc_output( int index, Fake_Buffer* center, Fake_Buffer* left, Fake_Buffer* right )
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{
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require( (unsigned int) index < osc_count );
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require( (center && left && right) || (!center && !left && !right) );
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T6W28_Osc& osc = *oscs [index];
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osc.outputs [1] = right;
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osc.outputs [2] = left;
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osc.outputs [3] = center;
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}
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void T6W28_Apu::output( Fake_Buffer* center, Fake_Buffer* left, Fake_Buffer* right )
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{
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for ( int i = 0; i < osc_count; i++ )
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osc_output( i, center, left, right );
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}
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void T6W28_Apu::reset()
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{
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last_time = 0;
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latch_left = 0;
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latch_right = 0;
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squares [0].reset();
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squares [1].reset();
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squares [2].reset();
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noise.reset();
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}
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void T6W28_Apu::run_until( sms_time_t end_time )
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{
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require( end_time >= last_time ); // end_time must not be before previous time
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if ( end_time > last_time )
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{
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// run oscillators
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for ( int i = 0; i < osc_count; ++i )
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{
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T6W28_Osc& osc = *oscs [i];
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if ( osc.outputs[1] )
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{
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if ( i < 3 )
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squares [i].run( last_time, end_time );
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else
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noise.run( last_time, end_time );
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}
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}
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last_time = end_time;
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}
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}
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bool T6W28_Apu::end_frame( sms_time_t end_time )
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{
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if ( end_time > last_time )
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run_until( end_time );
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assert( last_time >= end_time );
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last_time -= end_time;
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return(1);
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}
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static const unsigned char volumes [16] = {
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// volumes [i] = 64 * pow( 1.26, 15 - i ) / pow( 1.26, 15 )
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64, 50, 39, 31, 24, 19, 15, 12, 9, 7, 5, 4, 3, 2, 1, 0
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};
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void T6W28_Apu::write_data_left( sms_time_t time, int data )
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{
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require( (unsigned) data <= 0xFF );
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run_until( time );
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if ( data & 0x80 )
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latch_left = data;
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int index = (latch_left >> 5) & 3;
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if ( latch_left & 0x10 )
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{
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oscs [index]->volume_left = volumes [data & 15];
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}
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else if ( index < 3 )
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{
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T6W28_Square& sq = squares [index];
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if ( data & 0x80 )
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sq.period = (sq.period & 0xFF00) | (data << 4 & 0x00FF);
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else
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sq.period = (sq.period & 0x00FF) | (data << 8 & 0x3F00);
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}
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}
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void T6W28_Apu::write_data_right( sms_time_t time, int data )
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{
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require( (unsigned) data <= 0xFF );
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run_until( time );
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if ( data & 0x80 )
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latch_right = data;
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int index = (latch_right >> 5) & 3;
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//printf("%d\n", index);
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if ( latch_right & 0x10 )
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{
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oscs [index]->volume_right = volumes [data & 15];
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}
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else if ( index == 2 )
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{
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if ( data & 0x80 )
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noise.period_extra = (noise.period_extra & 0xFF00) | (data << 4 & 0x00FF);
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else
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noise.period_extra = (noise.period_extra & 0x00FF) | (data << 8 & 0x3F00);
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}
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else if(index == 3)
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{
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int select = data & 3;
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if ( select < 3 )
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noise.period = &noise_periods [select];
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else
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noise.period = &noise.period_extra;
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int const tap_disabled = 16;
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noise.tap = (data & 0x04) ? 13 : tap_disabled;
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noise.shifter = 0x4000;
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}
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}
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}
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