rockbox/apps/codecs/libgme/nes_apu.c

397 lines
11 KiB
C

// Nes_Snd_Emu 0.1.8. http://www.slack.net/~ant/
#include "nes_apu.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"
int const amp_range = 15;
void Apu_init( struct Nes_Apu* this )
{
this->tempo_ = (int)(FP_ONE_TEMPO);
this->dmc.apu = this;
this->dmc.prg_reader = NULL;
this->irq_notifier_ = NULL;
Synth_init( &this->square_synth );
Synth_init( &this->triangle.synth );
Synth_init( &this->noise.synth );
Synth_init( &this->dmc.synth );
Square_set_synth( &this->square1, &this->square_synth );
Square_set_synth( &this->square2, &this->square_synth );
this->oscs [0] = &this->square1.osc;
this->oscs [1] = &this->square2.osc;
this->oscs [2] = &this->triangle.osc;
this->oscs [3] = &this->noise.osc;
this->oscs [4] = &this->dmc.osc;
Apu_output( this, NULL );
this->dmc.nonlinear = false;
Apu_volume( this, (int)FP_ONE_VOLUME );
Apu_reset( this, false, 0 );
}
#if 0
// sq and tnd must use a fixed point frac where 1.0 = FP_ONE_VOLUME
void Apu_enable_nonlinear_( struct Nes_Apu* this, int sq, int tnd )
{
this->dmc.nonlinear = true;
Synth_volume( &this->square_synth, sq );
Synth_volume( &this->triangle.synth, (int)((long long)(FP_ONE_VOLUME * 2.752) * tnd / FP_ONE_VOLUME) );
Synth_volume( &this->noise.synth , (int)((long long)(FP_ONE_VOLUME * 1.849) * tnd / FP_ONE_VOLUME) );
Synth_volume( &this->dmc.synth , tnd );
this->square1 .osc.last_amp = 0;
this->square2 .osc.last_amp = 0;
this->triangle.osc.last_amp = 0;
this->noise .osc.last_amp = 0;
this->dmc .osc.last_amp = 0;
}
#endif
void Apu_volume( struct Nes_Apu* this, int v )
{
if ( !this->dmc.nonlinear )
{
Synth_volume( &this->square_synth, (int)((long long)((0.125 / 1.11) * FP_ONE_VOLUME) * v / amp_range / FP_ONE_VOLUME) ); // was 0.1128 1.108
Synth_volume( &this->triangle.synth,(int)((long long)((0.150 / 1.11) * FP_ONE_VOLUME) * v / amp_range / FP_ONE_VOLUME) ); // was 0.12765 1.175
Synth_volume( &this->noise.synth, (int)((long long)((0.095 / 1.11) * FP_ONE_VOLUME) * v / amp_range / FP_ONE_VOLUME) ); // was 0.0741 1.282
Synth_volume( &this->dmc.synth, (int)((long long)((0.450 / 1.11) * FP_ONE_VOLUME) * v / 2048 / FP_ONE_VOLUME) ); // was 0.42545 1.058
}
}
void Apu_output( struct Nes_Apu* this, struct Blip_Buffer* buffer )
{
int i;
for ( i = 0; i < apu_osc_count; i++ )
Apu_osc_output( this, i, buffer );
}
void Apu_set_tempo( struct Nes_Apu* this, int t )
{
this->tempo_ = t;
this->frame_period = (this->dmc.pal_mode ? 8314 : 7458);
if ( t != (int)FP_ONE_TEMPO )
this->frame_period = (int) ((this->frame_period * FP_ONE_TEMPO) / t) & ~1; // must be even
}
void Apu_reset( struct Nes_Apu* this, bool pal_mode, int initial_dmc_dac )
{
this->dmc.pal_mode = pal_mode;
Apu_set_tempo( this, this->tempo_ );
Square_reset( &this->square1 );
Square_reset( &this->square2 );
Triangle_reset( &this->triangle );
Noise_reset( &this->noise );
Dmc_reset( &this->dmc );
this->last_time = 0;
this->last_dmc_time = 0;
this->osc_enables = 0;
this->irq_flag = false;
this->earliest_irq_ = apu_no_irq;
this->frame_delay = 1;
Apu_write_register( this, 0, 0x4017, 0x00 );
Apu_write_register( this, 0, 0x4015, 0x00 );
addr_t addr;
for ( addr = apu_io_addr; addr <= 0x4013; addr++ )
Apu_write_register( this, 0, addr, (addr & 3) ? 0x00 : 0x10 );
this->dmc.dac = initial_dmc_dac;
if ( !this->dmc.nonlinear )
this->triangle.osc.last_amp = 15;
if ( !this->dmc.nonlinear ) // TODO: remove?
this->dmc.osc.last_amp = initial_dmc_dac; // prevent output transition
}
void Apu_irq_changed( struct Nes_Apu* this )
{
nes_time_t new_irq = this->dmc.next_irq;
if ( this->dmc.irq_flag | this->irq_flag ) {
new_irq = 0;
}
else if ( new_irq > this->next_irq ) {
new_irq = this->next_irq;
}
if ( new_irq != this->earliest_irq_ ) {
this->earliest_irq_ = new_irq;
if ( this->irq_notifier_ )
this->irq_notifier_( this->irq_data );
}
}
// frames
void Apu_run_until( struct Nes_Apu* this, nes_time_t end_time )
{
require( end_time >= this->last_dmc_time );
if ( end_time > Apu_next_dmc_read_time( this ) )
{
nes_time_t start = this->last_dmc_time;
this->last_dmc_time = end_time;
Dmc_run( &this->dmc, start, end_time );
}
}
static void run_until_( struct Nes_Apu* this, nes_time_t end_time )
{
require( end_time >= this->last_time );
if ( end_time == this->last_time )
return;
if ( this->last_dmc_time < end_time )
{
nes_time_t start = this->last_dmc_time;
this->last_dmc_time = end_time;
Dmc_run( &this->dmc, start, end_time );
}
while ( true )
{
// earlier of next frame time or end time
nes_time_t time = this->last_time + this->frame_delay;
if ( time > end_time )
time = end_time;
this->frame_delay -= time - this->last_time;
// run oscs to present
Square_run( &this->square1, this->last_time, time );
Square_run( &this->square2, this->last_time, time );
Triangle_run( &this->triangle, this->last_time, time );
Noise_run( &this->noise, this->last_time, time );
this->last_time = time;
if ( time == end_time )
break; // no more frames to run
// take frame-specific actions
this->frame_delay = this->frame_period;
switch ( this->frame++ )
{
case 0:
if ( !(this->frame_mode & 0xC0) ) {
this->next_irq = time + this->frame_period * 4 + 2;
this->irq_flag = true;
}
// fall through
case 2:
// clock length and sweep on frames 0 and 2
Osc_clock_length( &this->square1.osc, 0x20 );
Osc_clock_length( &this->square2.osc, 0x20 );
Osc_clock_length( &this->noise.osc, 0x20 );
Osc_clock_length( &this->triangle.osc, 0x80 ); // different bit for halt flag on triangle
Square_clock_sweep( &this->square1, -1 );
Square_clock_sweep( &this->square2, 0 );
// frame 2 is slightly shorter in mode 1
if ( this->dmc.pal_mode && this->frame == 3 )
this->frame_delay -= 2;
break;
case 1:
// frame 1 is slightly shorter in mode 0
if ( !this->dmc.pal_mode )
this->frame_delay -= 2;
break;
case 3:
this->frame = 0;
// frame 3 is almost twice as long in mode 1
if ( this->frame_mode & 0x80 )
this->frame_delay += this->frame_period - (this->dmc.pal_mode ? 2 : 6);
break;
}
// clock envelopes and linear counter every frame
Triangle_clock_linear_counter( &this->triangle );
Square_clock_envelope( &this->square1 );
Square_clock_envelope( &this->square2 );
Noise_clock_envelope( &this->noise );
}
}
static inline void zero_apu_osc( struct Nes_Osc* osc, struct Blip_Synth* synth, nes_time_t time )
{
struct Blip_Buffer* output = osc->output;
int last_amp = osc->last_amp;
osc->last_amp = 0;
if ( output && last_amp )
Synth_offset( synth, time, -osc->last_amp, output );
}
void Apu_end_frame( struct Nes_Apu* this, nes_time_t end_time )
{
if ( end_time > this->last_time )
run_until_( this, end_time );
if ( this->dmc.nonlinear )
{
zero_apu_osc( &this->square1.osc, this->square1.synth, this->last_time );
zero_apu_osc( &this->square2.osc, this->square2.synth, this->last_time );
zero_apu_osc( &this->triangle.osc, &this->triangle.synth, this->last_time );
zero_apu_osc( &this->noise.osc, &this->noise.synth, this->last_time );
zero_apu_osc( &this->dmc.osc, &this->dmc.synth, this->last_time );
}
// make times relative to new frame
this->last_time -= end_time;
require( this->last_time >= 0 );
this->last_dmc_time -= end_time;
require( this->last_dmc_time >= 0 );
if ( this->next_irq != apu_no_irq ) {
this->next_irq -= end_time;
check( this->next_irq >= 0 );
}
if ( this->dmc.next_irq != apu_no_irq ) {
this->dmc.next_irq -= end_time;
check( this->dmc.next_irq >= 0 );
}
if ( this->earliest_irq_ != apu_no_irq ) {
this->earliest_irq_ -= end_time;
if ( this->earliest_irq_ < 0 )
this->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 Apu_write_register( struct Nes_Apu* this, nes_time_t time, addr_t 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 - apu_io_addr) >= apu_io_size )
return;
run_until_( this, time );
if ( addr < 0x4014 )
{
// Write to channel
int osc_index = (addr - apu_io_addr) >> 2;
struct Nes_Osc* osc = this->oscs [osc_index];
int reg = addr & 3;
osc->regs [reg] = data;
osc->reg_written [reg] = true;
if ( osc_index == 4 )
{
// handle DMC specially
Dmc_write_register( &this->dmc, reg, data );
}
else if ( reg == 3 )
{
// load length counter
if ( (this->osc_enables >> osc_index) & 1 )
osc->length_counter = length_table [(data >> 3) & 0x1F];
// reset square phase
if ( osc_index == 0 ) this->square1.phase = square_phase_range - 1;
else if ( osc_index == 1 ) this->square2.phase = square_phase_range - 1;
}
}
else if ( addr == 0x4015 )
{
// Channel enables
int i;
for ( i = apu_osc_count; i--; )
if ( !((data >> i) & 1) )
this->oscs [i]->length_counter = 0;
bool recalc_irq = this->dmc.irq_flag;
this->dmc.irq_flag = false;
int old_enables = this->osc_enables;
this->osc_enables = data;
if ( !(data & 0x10) ) {
this->dmc.next_irq = apu_no_irq;
recalc_irq = true;
}
else if ( !(old_enables & 0x10) ) {
Dmc_start( &this->dmc ); // dmc just enabled
}
if ( recalc_irq )
Apu_irq_changed( this );
}
else if ( addr == 0x4017 )
{
// Frame mode
this->frame_mode = data;
bool irq_enabled = !(data & 0x40);
this->irq_flag &= irq_enabled;
this->next_irq = apu_no_irq;
// mode 1
this->frame_delay = (this->frame_delay & 1);
this->frame = 0;
if ( !(data & 0x80) )
{
// mode 0
this->frame = 1;
this->frame_delay += this->frame_period;
if ( irq_enabled )
this->next_irq = time + this->frame_delay + this->frame_period * 3 + 1;
}
Apu_irq_changed( this );
}
}
int Apu_read_status( struct Nes_Apu* this, nes_time_t time )
{
run_until_( this, time - 1 );
int result = (this->dmc.irq_flag << 7) | (this->irq_flag << 6);
int i;
for ( i = 0; i < apu_osc_count; i++ )
if ( this->oscs [i]->length_counter )
result |= 1 << i;
run_until_( this, time );
if ( this->irq_flag )
{
result |= 0x40;
this->irq_flag = false;
Apu_irq_changed( this );
}
//debug_printf( "%6d/%d Read $4015->$%02X\n", frame_delay, frame, result );
return result;
}