private void tickSweep(Pulse pulse)
{
if (pulse.sweep_period_counter == 0)
{
if (pulse.SWEEP_ENABLED)
{
int periodAdjustment = pulse.TIMER >> pulse.SWEEP_SHIFT;
int newPeriod;
if (pulse.SWEEP_NEGATE)
{
newPeriod = pulse.TIMER - periodAdjustment;
}
else
{
newPeriod = (pulse.TIMER + periodAdjustment);
}
if (0 < newPeriod && newPeriod < 0x7FF && pulse.SWEEP_SHIFT != 0)
{
pulse.TIMER = (ushort)newPeriod;
}
}
pulse.sweep_period_counter = pulse.SWEEP_PERIOD;
}
else
{
pulse.sweep_period_counter--;
}
}
private void tickLengthCounter(Pulse pulse)
{
if (!pulse.LENGTH_COUNTER_HALT)
{
pulse.current_length_counter -= 1;
if (pulse.current_length_counter < 0)
{
pulse.current_length_counter = 0;
}
}
}
private void tickEnvelopCounter(Pulse pulse)
{
if (pulse.envelope_counter == 0)
{
if (pulse.envelope_volume == 0)
{
if (pulse.ENVELOPE_LOOP)
{
pulse.envelope_volume = 15;
}
}
else
{
pulse.envelope_volume--;
}
pulse.envelope_counter = pulse.ENVELOPE_DIVIDER_PERIOD_OR_VOLUME;
}
else
{
pulse.envelope_counter--;
}
}
public float getPulseAudio(Pulse pulse, int timeInSamples)
{
if (!pulse.ENABLED || pulse.current_length_counter == 0)
{
return(0.0f);
}
//Frequency is the clock speed of the CPU ~ 1.7MH divided by 16 divied by the timer.
//TODO pretty much everything here, only looking at frequency flag right now
double frequency = 106250.0 / pulse.TIMER;
double normalizedSampleTime = timeInSamples * frequency / sampleRate;
double fractionalNormalizedSampleTime = normalizedSampleTime - Math.Floor(normalizedSampleTime);
float dutyPulse = fractionalNormalizedSampleTime < dutyMap[pulse.DUTY] ? 1 : -1;
byte volume = pulse.ENVELOPE_DIVIDER_PERIOD_OR_VOLUME;
if (!pulse.CONSTANT_VOLUME)
{
volume = pulse.envelope_volume;
}
return(dutyPulse * volume / 15);
}
