337 lines
6.7 KiB
C++
337 lines
6.7 KiB
C++
// Gb_Snd_Emu 0.1.5. http://www.slack.net/~ant/
|
|
|
|
#include "Gb_Apu.h"
|
|
|
|
#include <string.h>
|
|
|
|
/* Copyright (C) 2003-2006 Shay Green. This module is free software; you
|
|
can redistribute it and/or modify it under the terms of the GNU Lesser
|
|
General Public License as published by the Free Software Foundation; either
|
|
version 2.1 of the License, or (at your option) any later version. This
|
|
module 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 Lesser General Public License for more
|
|
details. You should have received a copy of the GNU Lesser General Public
|
|
License along with this module; if not, write to the Free Software Foundation,
|
|
Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */
|
|
|
|
#include "blargg_source.h"
|
|
|
|
// Gb_Osc
|
|
|
|
void Gb_Osc::reset()
|
|
{
|
|
delay = 0;
|
|
last_amp = 0;
|
|
length = 0;
|
|
output_select = 3;
|
|
output = outputs [output_select];
|
|
}
|
|
|
|
void Gb_Osc::clock_length()
|
|
{
|
|
if ( (regs [4] & len_enabled_mask) && length )
|
|
length--;
|
|
}
|
|
|
|
// Gb_Env
|
|
|
|
void Gb_Env::clock_envelope()
|
|
{
|
|
if ( env_delay && !--env_delay )
|
|
{
|
|
env_delay = regs [2] & 7;
|
|
int v = volume - 1 + (regs [2] >> 2 & 2);
|
|
if ( (unsigned) v < 15 )
|
|
volume = v;
|
|
}
|
|
}
|
|
|
|
bool Gb_Env::write_register( int reg, int data )
|
|
{
|
|
switch ( reg )
|
|
{
|
|
case 1:
|
|
length = 64 - (regs [1] & 0x3F);
|
|
break;
|
|
|
|
case 2:
|
|
if ( !(data >> 4) )
|
|
enabled = false;
|
|
break;
|
|
|
|
case 4:
|
|
if ( data & trigger )
|
|
{
|
|
env_delay = regs [2] & 7;
|
|
volume = regs [2] >> 4;
|
|
enabled = true;
|
|
if ( length == 0 )
|
|
length = 64;
|
|
return true;
|
|
}
|
|
}
|
|
return false;
|
|
}
|
|
|
|
// Gb_Square
|
|
|
|
void Gb_Square::reset()
|
|
{
|
|
phase = 0;
|
|
sweep_freq = 0;
|
|
sweep_delay = 0;
|
|
Gb_Env::reset();
|
|
}
|
|
|
|
void Gb_Square::clock_sweep()
|
|
{
|
|
int sweep_period = (regs [0] & period_mask) >> 4;
|
|
if ( sweep_period && sweep_delay && !--sweep_delay )
|
|
{
|
|
sweep_delay = sweep_period;
|
|
regs [3] = sweep_freq & 0xFF;
|
|
regs [4] = (regs [4] & ~0x07) | (sweep_freq >> 8 & 0x07);
|
|
|
|
int offset = sweep_freq >> (regs [0] & shift_mask);
|
|
if ( regs [0] & 0x08 )
|
|
offset = -offset;
|
|
sweep_freq += offset;
|
|
|
|
if ( sweep_freq < 0 )
|
|
{
|
|
sweep_freq = 0;
|
|
}
|
|
else if ( sweep_freq >= 2048 )
|
|
{
|
|
sweep_delay = 0; // don't modify channel frequency any further
|
|
sweep_freq = 2048; // silence sound immediately
|
|
}
|
|
}
|
|
}
|
|
|
|
void Gb_Square::run( blip_time_t time, blip_time_t end_time, int playing )
|
|
{
|
|
if ( sweep_freq == 2048 )
|
|
playing = false;
|
|
|
|
static unsigned char const table [4] = { 1, 2, 4, 6 };
|
|
int const duty = table [regs [1] >> 6];
|
|
int amp = volume & playing;
|
|
if ( phase >= duty )
|
|
amp = -amp;
|
|
|
|
int frequency = this->frequency();
|
|
if ( unsigned (frequency - 1) > 2040 ) // frequency < 1 || frequency > 2041
|
|
{
|
|
// really high frequency results in DC at half volume
|
|
amp = volume >> 1;
|
|
playing = false;
|
|
}
|
|
|
|
{
|
|
int delta = amp - last_amp;
|
|
if ( delta )
|
|
{
|
|
last_amp = amp;
|
|
synth->offset( time, delta, output );
|
|
}
|
|
}
|
|
|
|
time += delay;
|
|
if ( !playing )
|
|
time = end_time;
|
|
|
|
if ( time < end_time )
|
|
{
|
|
int const period = (2048 - frequency) * 4;
|
|
Blip_Buffer* const output = this->output;
|
|
int phase = this->phase;
|
|
int delta = amp * 2;
|
|
do
|
|
{
|
|
phase = (phase + 1) & 7;
|
|
if ( phase == 0 || phase == duty )
|
|
{
|
|
delta = -delta;
|
|
synth->offset_inline( time, delta, output );
|
|
}
|
|
time += period;
|
|
}
|
|
while ( time < end_time );
|
|
|
|
this->phase = phase;
|
|
last_amp = delta >> 1;
|
|
}
|
|
delay = time - end_time;
|
|
}
|
|
|
|
// Gb_Noise
|
|
|
|
void Gb_Noise::run( blip_time_t time, blip_time_t end_time, int playing )
|
|
{
|
|
int amp = volume & playing;
|
|
int tap = 13 - (regs [3] & 8);
|
|
if ( bits >> tap & 2 )
|
|
amp = -amp;
|
|
|
|
{
|
|
int delta = amp - last_amp;
|
|
if ( delta )
|
|
{
|
|
last_amp = amp;
|
|
synth->offset( time, delta, output );
|
|
}
|
|
}
|
|
|
|
time += delay;
|
|
if ( !playing )
|
|
time = end_time;
|
|
|
|
if ( time < end_time )
|
|
{
|
|
static unsigned char const table [8] = { 8, 16, 32, 48, 64, 80, 96, 112 };
|
|
int period = table [regs [3] & 7] << (regs [3] >> 4);
|
|
|
|
// keep parallel resampled time to eliminate time conversion in the loop
|
|
Blip_Buffer* const output = this->output;
|
|
const blip_resampled_time_t resampled_period =
|
|
output->resampled_duration( period );
|
|
blip_resampled_time_t resampled_time = output->resampled_time( time );
|
|
unsigned bits = this->bits;
|
|
int delta = amp * 2;
|
|
|
|
do
|
|
{
|
|
unsigned changed = (bits >> tap) + 1;
|
|
time += period;
|
|
bits <<= 1;
|
|
if ( changed & 2 )
|
|
{
|
|
delta = -delta;
|
|
bits |= 1;
|
|
synth->offset_resampled( resampled_time, delta, output );
|
|
}
|
|
resampled_time += resampled_period;
|
|
}
|
|
while ( time < end_time );
|
|
|
|
this->bits = bits;
|
|
last_amp = delta >> 1;
|
|
}
|
|
delay = time - end_time;
|
|
}
|
|
|
|
// Gb_Wave
|
|
|
|
inline void Gb_Wave::write_register( int reg, int data )
|
|
{
|
|
switch ( reg )
|
|
{
|
|
case 0:
|
|
if ( !(data & 0x80) )
|
|
enabled = false;
|
|
break;
|
|
|
|
case 1:
|
|
length = 256 - regs [1];
|
|
break;
|
|
|
|
case 2:
|
|
volume = data >> 5 & 3;
|
|
break;
|
|
|
|
case 4:
|
|
if ( data & trigger & regs [0] )
|
|
{
|
|
wave_pos = 0;
|
|
enabled = true;
|
|
if ( length == 0 )
|
|
length = 256;
|
|
}
|
|
}
|
|
}
|
|
|
|
void Gb_Wave::run( blip_time_t time, blip_time_t end_time, int playing )
|
|
{
|
|
int volume_shift = (volume - 1) & 7; // volume = 0 causes shift = 7
|
|
int frequency;
|
|
{
|
|
int amp = (wave [wave_pos] >> volume_shift & playing) * 2;
|
|
|
|
frequency = this->frequency();
|
|
if ( unsigned (frequency - 1) > 2044 ) // frequency < 1 || frequency > 2045
|
|
{
|
|
amp = 30 >> volume_shift & playing;
|
|
playing = false;
|
|
}
|
|
|
|
int delta = amp - last_amp;
|
|
if ( delta )
|
|
{
|
|
last_amp = amp;
|
|
synth->offset( time, delta, output );
|
|
}
|
|
}
|
|
|
|
time += delay;
|
|
if ( !playing )
|
|
time = end_time;
|
|
|
|
if ( time < end_time )
|
|
{
|
|
Blip_Buffer* const output = this->output;
|
|
int const period = (2048 - frequency) * 2;
|
|
int wave_pos = (this->wave_pos + 1) & (wave_size - 1);
|
|
|
|
do
|
|
{
|
|
int amp = (wave [wave_pos] >> volume_shift) * 2;
|
|
wave_pos = (wave_pos + 1) & (wave_size - 1);
|
|
int delta = amp - last_amp;
|
|
if ( delta )
|
|
{
|
|
last_amp = amp;
|
|
synth->offset_inline( time, delta, output );
|
|
}
|
|
time += period;
|
|
}
|
|
while ( time < end_time );
|
|
|
|
this->wave_pos = (wave_pos - 1) & (wave_size - 1);
|
|
}
|
|
delay = time - end_time;
|
|
}
|
|
|
|
// Gb_Apu::write_osc
|
|
|
|
void Gb_Apu::write_osc( int index, int reg, int data )
|
|
{
|
|
reg -= index * 5;
|
|
Gb_Square* sq = &square2;
|
|
switch ( index )
|
|
{
|
|
case 0:
|
|
sq = &square1; // FALLTHRU
|
|
case 1:
|
|
if ( sq->write_register( reg, data ) && index == 0 )
|
|
{
|
|
square1.sweep_freq = square1.frequency();
|
|
if ( (regs [0] & sq->period_mask) && (regs [0] & sq->shift_mask) )
|
|
{
|
|
square1.sweep_delay = 1; // cause sweep to recalculate now
|
|
square1.clock_sweep();
|
|
}
|
|
}
|
|
break;
|
|
|
|
case 2:
|
|
wave.write_register( reg, data );
|
|
break;
|
|
|
|
case 3:
|
|
if ( noise.write_register( reg, data ) )
|
|
noise.bits = 0x7FFF;
|
|
}
|
|
}
|