f40bfc9267
Change-Id: Id7f4717d51ed02d67cb9f9cb3c0ada4a81843f97 Reviewed-on: http://gerrit.rockbox.org/137 Reviewed-by: Nils Wallménius <nils@rockbox.org> Tested-by: Nils Wallménius <nils@rockbox.org>
138 lines
3.8 KiB
C
138 lines
3.8 KiB
C
// Nes_Snd_Emu 0.1.8. http://www.slack.net/~ant/
|
|
|
|
#include "nes_namco_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 Namco_init( struct Nes_Namco_Apu* this )
|
|
{
|
|
Synth_init( &this->synth );
|
|
|
|
Namco_output( this, NULL );
|
|
Namco_volume( this, (int)FP_ONE_VOLUME );
|
|
Namco_reset( this );
|
|
}
|
|
|
|
void Namco_reset( struct Nes_Namco_Apu* this )
|
|
{
|
|
this->last_time = 0;
|
|
this->addr_reg = 0;
|
|
|
|
int i;
|
|
for ( i = 0; i < namco_reg_count; i++ )
|
|
this->reg [i] = 0;
|
|
|
|
for ( i = 0; i < namco_osc_count; i++ )
|
|
{
|
|
struct Namco_Osc* osc = &this->oscs [i];
|
|
osc->delay = 0;
|
|
osc->last_amp = 0;
|
|
osc->wave_pos = 0;
|
|
}
|
|
}
|
|
|
|
void Namco_output( struct Nes_Namco_Apu* this, struct Blip_Buffer* buf )
|
|
{
|
|
int i;
|
|
for ( i = 0; i < namco_osc_count; i++ )
|
|
Namco_osc_output( this, i, buf );
|
|
}
|
|
|
|
void Namco_end_frame( struct Nes_Namco_Apu* this, blip_time_t time )
|
|
{
|
|
if ( time > this->last_time )
|
|
Namco_run_until( this, time );
|
|
|
|
assert( this->last_time >= time );
|
|
this->last_time -= time;
|
|
}
|
|
|
|
void Namco_run_until( struct Nes_Namco_Apu* this, blip_time_t nes_end_time )
|
|
{
|
|
int active_oscs = (this->reg [0x7F] >> 4 & 7) + 1;
|
|
int i;
|
|
for ( i = namco_osc_count - active_oscs; i < namco_osc_count; i++ )
|
|
{
|
|
struct Namco_Osc* osc = &this->oscs [i];
|
|
struct Blip_Buffer* output = osc->output;
|
|
if ( !output )
|
|
continue;
|
|
|
|
blip_resampled_time_t time =
|
|
Blip_resampled_time( output, this->last_time ) + osc->delay;
|
|
blip_resampled_time_t end_time = Blip_resampled_time( output, nes_end_time );
|
|
osc->delay = 0;
|
|
if ( time < end_time )
|
|
{
|
|
const uint8_t* osc_reg = &this->reg [i * 8 + 0x40];
|
|
if ( !(osc_reg [4] & 0xE0) )
|
|
continue;
|
|
|
|
int volume = osc_reg [7] & 15;
|
|
if ( !volume )
|
|
continue;
|
|
|
|
int freq = (osc_reg [4] & 3) * 0x10000 + osc_reg [2] * 0x100L + osc_reg [0];
|
|
if ( freq < 64 * active_oscs )
|
|
continue; // prevent low frequencies from excessively delaying freq changes
|
|
|
|
int const master_clock_divider = 12; // NES time derived via divider of master clock
|
|
int const n106_divider = 45; // N106 then divides master clock by this
|
|
int const max_freq = 0x3FFFF;
|
|
int const lowest_freq_period = (max_freq + 1) * n106_divider / master_clock_divider;
|
|
// divide by 8 to avoid overflow
|
|
blip_resampled_time_t period =
|
|
Blip_resampled_duration( output, lowest_freq_period / 8 ) / freq * 8 * active_oscs;
|
|
|
|
int wave_size = 32 - (osc_reg [4] >> 2 & 7) * 4;
|
|
if ( !wave_size )
|
|
continue;
|
|
|
|
int last_amp = osc->last_amp;
|
|
int wave_pos = osc->wave_pos;
|
|
|
|
Blip_set_modified( output );
|
|
|
|
do
|
|
{
|
|
// read wave sample
|
|
int addr = wave_pos + osc_reg [6];
|
|
int sample = this->reg [addr >> 1] >> (addr << 2 & 4);
|
|
wave_pos++;
|
|
sample = (sample & 15) * volume;
|
|
|
|
// output impulse if amplitude changed
|
|
int delta = sample - last_amp;
|
|
if ( delta )
|
|
{
|
|
last_amp = sample;
|
|
Synth_offset_resampled( &this->synth, time, delta, output );
|
|
}
|
|
|
|
// next sample
|
|
time += period;
|
|
if ( wave_pos >= wave_size )
|
|
wave_pos = 0;
|
|
}
|
|
while ( time < end_time );
|
|
|
|
osc->wave_pos = wave_pos;
|
|
osc->last_amp = last_amp;
|
|
}
|
|
osc->delay = time - end_time;
|
|
}
|
|
|
|
this->last_time = nes_end_time;
|
|
}
|
|
|