cog/Frameworks/GME/gme/Nes_Apu.cpp

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// Nes_Snd_Emu $vers. http://www.slack.net/~ant/
#include "Nes_Apu.h"
/* Copyright (C) 2003-2008 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"
int const amp_range = 15;
Nes_Apu::Nes_Apu() :
square1( &square_synth ),
square2( &square_synth )
{
tempo_ = 1.0;
dmc.apu = this;
oscs [0] = &square1;
oscs [1] = &square2;
oscs [2] = ▵
oscs [3] = &noise;
oscs [4] = &dmc;
set_output( NULL );
dmc.nonlinear = false;
volume( 1.0 );
reset( false );
}
void Nes_Apu::treble_eq( const blip_eq_t& eq )
{
square_synth .treble_eq( eq );
triangle.synth.treble_eq( eq );
noise .synth.treble_eq( eq );
dmc .synth.treble_eq( eq );
}
void Nes_Apu::enable_nonlinear_( double sq, double tnd )
{
dmc.nonlinear = true;
square_synth.volume( sq );
triangle.synth.volume( tnd * 2.752 );
noise .synth.volume( tnd * 1.849 );
dmc .synth.volume( tnd );
square1 .last_amp = 0;
square2 .last_amp = 0;
triangle.last_amp = 0;
noise .last_amp = 0;
dmc .last_amp = 0;
}
void Nes_Apu::volume( double v )
{
if ( !dmc.nonlinear )
{
v *= 1.0 / 1.11; // TODO: merge into values below
square_synth .volume( 0.125 / amp_range * v ); // was 0.1128 1.108
triangle.synth.volume( 0.150 / amp_range * v ); // was 0.12765 1.175
noise .synth.volume( 0.095 / amp_range * v ); // was 0.0741 1.282
dmc .synth.volume( 0.450 / 2048 * v ); // was 0.42545 1.058
}
}
void Nes_Apu::set_output( Blip_Buffer* buffer )
{
for ( int i = 0; i < osc_count; ++i )
set_output( i, buffer );
}
void Nes_Apu::set_tempo( double t )
{
tempo_ = t;
frame_period = (dmc.pal_mode ? 8314 : 7458);
if ( t != 1.0 )
frame_period = (int) (frame_period / t) & ~1; // must be even
}
void Nes_Apu::reset( bool pal_mode, int initial_dmc_dac )
{
dmc.pal_mode = pal_mode;
set_tempo( tempo_ );
square1.reset();
square2.reset();
triangle.reset();
noise.reset();
dmc.reset();
last_time = 0;
last_dmc_time = 0;
osc_enables = 0;
irq_flag = false;
enable_w4011 = true;
earliest_irq_ = no_irq;
frame_delay = 1;
write_register( 0, 0x4017, 0x00 );
write_register( 0, 0x4015, 0x00 );
for ( int addr = io_addr; addr <= 0x4013; addr++ )
write_register( 0, addr, (addr & 3) ? 0x00 : 0x10 );
dmc.dac = initial_dmc_dac;
if ( !dmc.nonlinear )
triangle.last_amp = 15;
if ( !dmc.nonlinear ) // TODO: remove?
dmc.last_amp = initial_dmc_dac; // prevent output transition
}
void Nes_Apu::irq_changed()
{
blip_time_t new_irq = dmc.next_irq;
if ( dmc.irq_flag | irq_flag ) {
new_irq = 0;
}
else if ( new_irq > next_irq ) {
new_irq = next_irq;
}
if ( new_irq != earliest_irq_ ) {
earliest_irq_ = new_irq;
if ( irq_notifier.f )
irq_notifier.f( irq_notifier.data );
}
}
// frames
void Nes_Apu::run_until( blip_time_t end_time )
{
require( end_time >= last_dmc_time );
if ( end_time > next_dmc_read_time() )
{
blip_time_t start = last_dmc_time;
last_dmc_time = end_time;
dmc.run( start, end_time );
}
}
void Nes_Apu::run_until_( blip_time_t end_time )
{
require( end_time >= last_time );
if ( end_time == last_time )
return;
if ( last_dmc_time < end_time )
{
blip_time_t start = last_dmc_time;
last_dmc_time = end_time;
dmc.run( start, end_time );
}
while ( true )
{
// earlier of next frame time or end time
blip_time_t time = last_time + frame_delay;
if ( time > end_time )
time = end_time;
frame_delay -= time - last_time;
// run oscs to present
square1.run( last_time, time );
square2.run( last_time, time );
triangle.run( last_time, time );
noise.run( last_time, time );
last_time = time;
if ( time == end_time )
break; // no more frames to run
// take frame-specific actions
frame_delay = frame_period;
switch ( frame++ )
{
case 0:
if ( !(frame_mode & 0xC0) ) {
next_irq = time + frame_period * 4 + 2;
irq_flag = true;
}
// fall through
case 2:
// clock length and sweep on frames 0 and 2
square1.clock_length( 0x20 );
square2.clock_length( 0x20 );
noise.clock_length( 0x20 );
triangle.clock_length( 0x80 ); // different bit for halt flag on triangle
square1.clock_sweep( -1 );
square2.clock_sweep( 0 );
// frame 2 is slightly shorter in mode 1
if ( dmc.pal_mode && frame == 3 )
frame_delay -= 2;
break;
case 1:
// frame 1 is slightly shorter in mode 0
if ( !dmc.pal_mode )
frame_delay -= 2;
break;
case 3:
frame = 0;
// frame 3 is almost twice as long in mode 1
if ( frame_mode & 0x80 )
frame_delay += frame_period - (dmc.pal_mode ? 2 : 6);
break;
}
// clock envelopes and linear counter every frame
triangle.clock_linear_counter();
square1.clock_envelope();
square2.clock_envelope();
noise.clock_envelope();
}
}
template<class T>
inline void zero_apu_osc( T* osc, blip_time_t time )
{
Blip_Buffer* output = osc->output;
int last_amp = osc->last_amp;
osc->last_amp = 0;
if ( output && last_amp )
osc->synth.offset( time, -last_amp, output );
}
void Nes_Apu::end_frame( blip_time_t end_time )
{
if ( end_time > last_time )
run_until_( end_time );
if ( dmc.nonlinear )
{
zero_apu_osc( &square1, last_time );
zero_apu_osc( &square2, last_time );
zero_apu_osc( &triangle, last_time );
zero_apu_osc( &noise, last_time );
zero_apu_osc( &dmc, last_time );
}
// make times relative to new frame
last_time -= end_time;
require( last_time >= 0 );
last_dmc_time -= end_time;
require( last_dmc_time >= 0 );
if ( next_irq != no_irq ) {
next_irq -= end_time;
check( next_irq >= 0 );
}
if ( dmc.next_irq != no_irq ) {
dmc.next_irq -= end_time;
check( dmc.next_irq >= 0 );
}
if ( earliest_irq_ != no_irq ) {
earliest_irq_ -= end_time;
if ( earliest_irq_ < 0 )
earliest_irq_ = 0;
}
}
// registers
static const unsigned char length_table [0x20] = {
0x0A, 0xFE, 0x14, 0x02, 0x28, 0x04, 0x50, 0x06,
0xA0, 0x08, 0x3C, 0x0A, 0x0E, 0x0C, 0x1A, 0x0E,
0x0C, 0x10, 0x18, 0x12, 0x30, 0x14, 0x60, 0x16,
0xC0, 0x18, 0x48, 0x1A, 0x10, 0x1C, 0x20, 0x1E
};
void Nes_Apu::write_register( blip_time_t time, int addr, int data )
{
require( addr > 0x20 ); // addr must be actual address (i.e. 0x40xx)
require( (unsigned) data <= 0xFF );
// Ignore addresses outside range
if ( unsigned (addr - io_addr) >= io_size )
return;
run_until_( time );
if ( addr < 0x4014 )
{
// Write to channel
int osc_index = (addr - io_addr) >> 2;
Nes_Osc* osc = oscs [osc_index];
int reg = addr & 3;
osc->regs [reg] = data;
osc->reg_written [reg] = true;
if ( osc_index == 4 )
{
// handle DMC specially
if ( enable_w4011 || reg != 1 )
dmc.write_register( reg, data );
}
else if ( reg == 3 )
{
// load length counter
if ( (osc_enables >> osc_index) & 1 )
osc->length_counter = length_table [(data >> 3) & 0x1F];
// reset square phase
if ( osc_index < 2 )
((Nes_Square*) osc)->phase = Nes_Square::phase_range - 1;
}
}
else if ( addr == 0x4015 )
{
// Channel enables
for ( int i = osc_count; i--; )
if ( !((data >> i) & 1) )
oscs [i]->length_counter = 0;
bool recalc_irq = dmc.irq_flag;
dmc.irq_flag = false;
int old_enables = osc_enables;
osc_enables = data;
if ( !(data & 0x10) ) {
dmc.next_irq = no_irq;
recalc_irq = true;
}
else if ( !(old_enables & 0x10) ) {
dmc.start(); // dmc just enabled
}
if ( recalc_irq )
irq_changed();
}
else if ( addr == 0x4017 )
{
// Frame mode
frame_mode = data;
bool irq_enabled = !(data & 0x40);
irq_flag &= irq_enabled;
next_irq = no_irq;
// mode 1
frame_delay = (frame_delay & 1);
frame = 0;
if ( !(data & 0x80) )
{
// mode 0
frame = 1;
frame_delay += frame_period;
if ( irq_enabled )
next_irq = time + frame_delay + frame_period * 3 + 1;
}
irq_changed();
}
}
int Nes_Apu::read_status( blip_time_t time )
{
run_until_( time - 1 );
int result = (dmc.irq_flag << 7) | (irq_flag << 6);
for ( int i = 0; i < osc_count; i++ )
if ( oscs [i]->length_counter )
result |= 1 << i;
run_until_( time );
if ( irq_flag )
{
result |= 0x40;
irq_flag = false;
irq_changed();
}
//dprintf( "%6d/%d Read $4015->$%02X\n", frame_delay, frame, result );
return result;
}