From f40bfc9267b13b54e6379dfe7539447662879d24 Mon Sep 17 00:00:00 2001 From: Sean Bartell Date: Sat, 25 Jun 2011 21:32:25 -0400 Subject: Add codecs to librbcodec. MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Change-Id: Id7f4717d51ed02d67cb9f9cb3c0ada4a81843f97 Reviewed-on: http://gerrit.rockbox.org/137 Reviewed-by: Nils Wallménius Tested-by: Nils Wallménius --- lib/rbcodec/codecs/libgme/nes_vrc6_apu.c | 192 +++++++++++++++++++++++++++++++ 1 file changed, 192 insertions(+) create mode 100644 lib/rbcodec/codecs/libgme/nes_vrc6_apu.c (limited to 'lib/rbcodec/codecs/libgme/nes_vrc6_apu.c') diff --git a/lib/rbcodec/codecs/libgme/nes_vrc6_apu.c b/lib/rbcodec/codecs/libgme/nes_vrc6_apu.c new file mode 100644 index 0000000000..99a9ae3fed --- /dev/null +++ b/lib/rbcodec/codecs/libgme/nes_vrc6_apu.c @@ -0,0 +1,192 @@ + // Nes_Snd_Emu 0.1.8. http://www.slack.net/~ant/ + +#include "nes_vrc6_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" + +void Vrc6_init( struct Nes_Vrc6_Apu* this ) +{ + Synth_init( &this->saw_synth ); + Synth_init( &this->square_synth ); + + Vrc6_output( this, NULL ); + Vrc6_volume( this, (int)FP_ONE_VOLUME ); + Vrc6_reset( this ); +} + +void Vrc6_reset( struct Nes_Vrc6_Apu* this ) +{ + this->last_time = 0; + int i; + for ( i = 0; i < vrc6_osc_count; i++ ) + { + struct Vrc6_Osc* osc = &this->oscs [i]; + int j; + for ( j = 0; j < vrc6_reg_count; j++ ) + osc->regs [j] = 0; + osc->delay = 0; + osc->last_amp = 0; + osc->phase = 1; + osc->amp = 0; + } +} + +void Vrc6_output( struct Nes_Vrc6_Apu* this, struct Blip_Buffer* buf ) +{ + int i; + for ( i = 0; i < vrc6_osc_count; i++ ) + Vrc6_osc_output( this, i, buf ); +} + +void run_square( struct Nes_Vrc6_Apu* this, struct Vrc6_Osc* osc, blip_time_t end_time ); +void run_saw( struct Nes_Vrc6_Apu* this, blip_time_t end_time ); +static void Vrc6_run_until( struct Nes_Vrc6_Apu* this, blip_time_t time ) +{ + require( time >= this->last_time ); + run_square( this, &this->oscs [0], time ); + run_square( this, &this->oscs [1], time ); + run_saw( this, time ); + this->last_time = time; +} + +void Vrc6_write_osc( struct Nes_Vrc6_Apu* this, blip_time_t time, int osc_index, int reg, int data ) +{ + require( (unsigned) osc_index < vrc6_osc_count ); + require( (unsigned) reg < vrc6_reg_count ); + + Vrc6_run_until( this, time ); + this->oscs [osc_index].regs [reg] = data; +} + +void Vrc6_end_frame( struct Nes_Vrc6_Apu* this, blip_time_t time ) +{ + if ( time > this->last_time ) + Vrc6_run_until( this, time ); + + assert( this->last_time >= time ); + this->last_time -= time; +} + +void run_square( struct Nes_Vrc6_Apu* this, struct Vrc6_Osc* osc, blip_time_t end_time ) +{ + struct Blip_Buffer* output = osc->output; + if ( !output ) + return; + + int volume = osc->regs [0] & 15; + if ( !(osc->regs [2] & 0x80) ) + volume = 0; + + int gate = osc->regs [0] & 0x80; + int duty = ((osc->regs [0] >> 4) & 7) + 1; + int delta = ((gate || osc->phase < duty) ? volume : 0) - osc->last_amp; + blip_time_t time = this->last_time; + if ( delta ) + { + osc->last_amp += delta; + Blip_set_modified( output ); + Synth_offset( &this->square_synth, time, delta, output ); + } + + time += osc->delay; + osc->delay = 0; + int period = Vrc6_osc_period( osc ); + if ( volume && !gate && period > 4 ) + { + if ( time < end_time ) + { + int phase = osc->phase; + Blip_set_modified( output ); + + do + { + phase++; + if ( phase == 16 ) + { + phase = 0; + osc->last_amp = volume; + Synth_offset( &this->square_synth, time, volume, output ); + } + if ( phase == duty ) + { + osc->last_amp = 0; + Synth_offset( &this->square_synth, time, -volume, output ); + } + time += period; + } + while ( time < end_time ); + + osc->phase = phase; + } + osc->delay = time - end_time; + } +} + +void run_saw( struct Nes_Vrc6_Apu* this, blip_time_t end_time ) +{ + struct Vrc6_Osc* osc = &this->oscs [2]; + struct Blip_Buffer* output = osc->output; + if ( !output ) + return; + Blip_set_modified( output ); + + int amp = osc->amp; + int amp_step = osc->regs [0] & 0x3F; + blip_time_t time = this->last_time; + int last_amp = osc->last_amp; + if ( !(osc->regs [2] & 0x80) || !(amp_step | amp) ) + { + osc->delay = 0; + int delta = (amp >> 3) - last_amp; + last_amp = amp >> 3; + Synth_offset( &this->saw_synth, time, delta, output ); + } + else + { + time += osc->delay; + if ( time < end_time ) + { + int period = Vrc6_osc_period( osc ) * 2; + int phase = osc->phase; + + do + { + if ( --phase == 0 ) + { + phase = 7; + amp = 0; + } + + int delta = (amp >> 3) - last_amp; + if ( delta ) + { + last_amp = amp >> 3; + Synth_offset( &this->saw_synth, time, delta, output ); + } + + time += period; + amp = (amp + amp_step) & 0xFF; + } + while ( time < end_time ); + + osc->phase = phase; + osc->amp = amp; + } + + osc->delay = time - end_time; + } + + osc->last_amp = last_amp; +} + -- cgit v1.2.3