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Diffstat (limited to 'plugins/gme/game-music-emu-0.6.0/gme/Nes_Apu.cpp')
-rw-r--r--plugins/gme/game-music-emu-0.6.0/gme/Nes_Apu.cpp391
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diff --git a/plugins/gme/game-music-emu-0.6.0/gme/Nes_Apu.cpp b/plugins/gme/game-music-emu-0.6.0/gme/Nes_Apu.cpp
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index 00000000..68edb446
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+++ b/plugins/gme/game-music-emu-0.6.0/gme/Nes_Apu.cpp
@@ -0,0 +1,391 @@
+// 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;
+
+Nes_Apu::Nes_Apu() :
+ square1( &square_synth ),
+ square2( &square_synth )
+{
+ tempo_ = 1.0;
+ dmc.apu = this;
+ dmc.prg_reader = NULL;
+ irq_notifier_ = NULL;
+
+ oscs [0] = &square1;
+ oscs [1] = &square2;
+ oscs [2] = ▵
+ oscs [3] = &noise;
+ oscs [4] = &dmc;
+
+ output( NULL );
+ 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 v )
+{
+ dmc.nonlinear = true;
+ square_synth.volume( 1.3 * 0.25751258 / 0.742467605 * 0.25 / amp_range * v );
+
+ const double tnd = 0.48 / 202 * nonlinear_tnd_gain();
+ triangle.synth.volume( 3.0 * tnd );
+ noise.synth.volume( 2.0 * tnd );
+ 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 )
+{
+ dmc.nonlinear = false;
+ square_synth.volume( 0.1128 / amp_range * v );
+ triangle.synth.volume( 0.12765 / amp_range * v );
+ noise.synth.volume( 0.0741 / amp_range * v );
+ dmc.synth.volume( 0.42545 / 127 * v );
+}
+
+void Nes_Apu::output( Blip_Buffer* buffer )
+{
+ for ( int i = 0; i < osc_count; i++ )
+ osc_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;
+ earliest_irq_ = no_irq;
+ frame_delay = 1;
+ write_register( 0, 0x4017, 0x00 );
+ write_register( 0, 0x4015, 0x00 );
+
+ for ( nes_addr_t addr = start_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()
+{
+ nes_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_ )
+ irq_notifier_( irq_data );
+ }
+}
+
+// frames
+
+void Nes_Apu::run_until( nes_time_t end_time )
+{
+ require( end_time >= last_dmc_time );
+ if ( end_time > next_dmc_read_time() )
+ {
+ nes_time_t start = last_dmc_time;
+ last_dmc_time = end_time;
+ dmc.run( start, end_time );
+ }
+}
+
+void Nes_Apu::run_until_( nes_time_t end_time )
+{
+ require( end_time >= last_time );
+
+ if ( end_time == last_time )
+ return;
+
+ if ( last_dmc_time < end_time )
+ {
+ nes_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
+ nes_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, nes_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( nes_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( nes_time_t time, nes_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 - start_addr) > end_addr - start_addr )
+ return;
+
+ run_until_( time );
+
+ if ( addr < 0x4014 )
+ {
+ // Write to channel
+ int osc_index = (addr - start_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
+ 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( nes_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();
+ }
+
+ //debug_printf( "%6d/%d Read $4015->$%02X\n", frame_delay, frame, result );
+
+ return result;
+}
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