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330 lines
6.6 KiB
C++
330 lines
6.6 KiB
C++
// Sms_Snd_Emu 0.1.4. http://www.slack.net/~ant/
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#include "Sms_Apu.h"
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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 more
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details. You should have received a copy of the GNU Lesser General Public
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License along with this module; if not, write to the Free Software Foundation,
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Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */
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#include "blargg_source.h"
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// Sms_Osc
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Sms_Osc::Sms_Osc()
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{
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output = 0;
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outputs [0] = 0; // always stays NULL
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outputs [1] = 0;
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outputs [2] = 0;
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outputs [3] = 0;
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}
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void Sms_Osc::reset()
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{
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delay = 0;
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last_amp = 0;
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volume = 0;
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output_select = 3;
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output = outputs [3];
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}
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// Sms_Square
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inline void Sms_Square::reset()
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{
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period = 0;
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phase = 0;
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Sms_Osc::reset();
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}
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void Sms_Square::run( blip_time_t time, blip_time_t end_time )
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{
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if ( !volume || period <= 128 )
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{
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// ignore 16kHz and higher
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if ( last_amp )
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{
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synth->offset( time, -last_amp, output );
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last_amp = 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 = phase ? volume : -volume;
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{
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int delta = amp - last_amp;
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if ( delta )
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{
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last_amp = amp;
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synth->offset( time, delta, output );
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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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Blip_Buffer* const output = this->output;
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int delta = amp * 2;
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do
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{
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delta = -delta;
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synth->offset_inline( time, delta, output );
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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 = phase ? volume : -volume;
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}
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}
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delay = time - end_time;
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}
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// Sms_Noise
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static int const noise_periods [3] = { 0x100, 0x200, 0x400 };
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inline void Sms_Noise::reset()
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{
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period = &noise_periods [0];
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shifter = 0x8000;
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feedback = 0x9000;
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Sms_Osc::reset();
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}
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void Sms_Noise::run( blip_time_t time, blip_time_t end_time )
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{
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int amp = volume;
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if ( shifter & 1 )
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amp = -amp;
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{
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int delta = amp - last_amp;
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if ( delta )
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{
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last_amp = amp;
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synth.offset( time, delta, output );
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}
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}
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time += delay;
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if ( !volume )
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time = end_time;
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if ( time < end_time )
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{
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Blip_Buffer* const output = this->output;
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unsigned shifter = this->shifter;
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int delta = amp * 2;
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int period = *this->period * 2;
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if ( !period )
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period = 16;
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do
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{
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int changed = shifter + 1;
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shifter = (feedback & -(shifter & 1)) ^ (shifter >> 1);
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if ( changed & 2 ) // true if bits 0 and 1 differ
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{
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delta = -delta;
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synth.offset_inline( time, delta, output );
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}
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time += period;
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}
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while ( time < end_time );
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this->shifter = shifter;
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this->last_amp = delta >> 1;
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}
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delay = time - end_time;
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}
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// Sms_Apu
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Sms_Apu::Sms_Apu()
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{
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for ( int i = 0; i < 3; i++ )
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{
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squares [i].synth = &square_synth;
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oscs [i] = &squares [i];
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}
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oscs [3] = &noise;
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volume( 1.0 );
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reset();
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}
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Sms_Apu::~Sms_Apu()
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{
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}
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void Sms_Apu::volume( double vol )
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{
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vol *= 0.85 / (osc_count * 64 * 2);
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square_synth.volume( vol );
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noise.synth.volume( vol );
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}
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void Sms_Apu::treble_eq( const blip_eq_t& eq )
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{
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square_synth.treble_eq( eq );
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noise.synth.treble_eq( eq );
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}
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void Sms_Apu::osc_output( int index, Blip_Buffer* center, Blip_Buffer* left, Blip_Buffer* right )
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{
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require( (unsigned) index < osc_count );
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require( (center && left && right) || (!center && !left && !right) );
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Sms_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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osc.output = osc.outputs [osc.output_select];
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}
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void Sms_Apu::output( Blip_Buffer* center, Blip_Buffer* left, Blip_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 Sms_Apu::reset( unsigned feedback, int noise_width )
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{
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last_time = 0;
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latch = 0;
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if ( !feedback || !noise_width )
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{
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feedback = 0x0009;
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noise_width = 16;
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}
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// convert to "Galios configuration"
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looped_feedback = 1 << (noise_width - 1);
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noise_feedback = 0;
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while ( noise_width-- )
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{
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noise_feedback = (noise_feedback << 1) | (feedback & 1);
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feedback >>= 1;
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}
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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 Sms_Apu::run_until( blip_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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Sms_Osc& osc = *oscs [i];
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if ( osc.output )
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{
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osc.output->set_modified();
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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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void Sms_Apu::end_frame( blip_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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}
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void Sms_Apu::write_ggstereo( blip_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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for ( int i = 0; i < osc_count; i++ )
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{
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Sms_Osc& osc = *oscs [i];
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int flags = data >> i;
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Blip_Buffer* old_output = osc.output;
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osc.output_select = (flags >> 3 & 2) | (flags & 1);
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osc.output = osc.outputs [osc.output_select];
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if ( osc.output != old_output && osc.last_amp )
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{
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if ( old_output )
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{
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old_output->set_modified();
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square_synth.offset( time, -osc.last_amp, old_output );
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}
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osc.last_amp = 0;
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}
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}
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}
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// volumes [i] = 64 * pow( 1.26, 15 - i ) / pow( 1.26, 15 )
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static unsigned char const volumes [16] = {
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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 Sms_Apu::write_data( blip_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 = data;
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int index = (latch >> 5) & 3;
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if ( latch & 0x10 )
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{
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oscs [index]->volume = volumes [data & 15];
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}
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else if ( index < 3 )
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{
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Sms_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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else
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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 = &squares [2].period;
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noise.feedback = (data & 0x04) ? noise_feedback : looped_feedback;
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noise.shifter = 0x8000;
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}
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}
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