void Nes_Vrc6_Apu::run_square( Vrc6_Osc& osc, blip_time_t end_time )
{
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 = last_time;
if ( delta )
{
osc.last_amp += delta;
output->set_modified();
square_synth.offset( time, delta, output );
}
time += osc.delay;
osc.delay = 0;
int period = osc.period();
if ( volume && !gate && period > 4 )
{
if ( time < end_time )
{
int phase = osc.phase;
output->set_modified();
do
{
phase++;
if ( phase == 16 )
{
phase = 0;
osc.last_amp = volume;
square_synth.offset( time, volume, output );
}
if ( phase == duty )
{
osc.last_amp = 0;
square_synth.offset( time, -volume, output );
}
time += period;
}
while ( time < end_time );
osc.phase = phase;
}
osc.delay = time - end_time;
}
}
void Nes_Vrc7_Apu::end_frame( blip_time_t time )
{
if ( time > next_time )
run_until( time );
next_time -= time;
assert( next_time >= 0 );
for ( int i = osc_count; --i >= 0; )
{
Blip_Buffer* output = oscs [i].output;
if ( output )
output->set_modified();
}
}
void Nes_Vrc6_Apu::run_saw( blip_time_t end_time )
{
Vrc6_Osc& osc = oscs [2];
Blip_Buffer* output = osc.output;
if ( !output )
return;
output->set_modified();
int amp = osc.amp;
int amp_step = osc.regs [0] & 0x3F;
blip_time_t time = 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;
saw_synth.offset( time, delta, output );
}