private void UpdateSquareWave_(Channel channel, int total_frames)
{
if (channel.status)
{
var square = channel.square_wave;
while (total_frames > 0)
{
int frames = (int)(square.ticks / APU_TICKS);
byte sample = Apu.CHANNELX_SAMPLE(channel, square.sample);
if (frames <= total_frames)
{
square.ticks = square.period;
square.position = (byte)((square.position + 1) % DUTY_CYCLE_COUNT);
square.sample = Apu.GetDuty(square.duty, square.position);
}
else
{
frames = total_frames;
square.ticks -= (uint)frames * APU_TICKS;
}
channel.accumulator += sample * (uint)frames;
total_frames -= frames;
}
}
}
public void UpdateNoise_(int total_frames)
{
var channel4 = this.Channel4;
if (channel4.status)
{
var noise = this.noise;
while (total_frames > 0)
{
int frames = (int)(noise.ticks / APU_TICKS);
byte sample = Apu.CHANNELX_SAMPLE(channel4, noise.sample);
if (noise.clock_shift <= NOISE_MAX_CLOCK_SHIFT)
{
if (frames <= total_frames)
{
ushort bit = (ushort)((noise.lfsr ^ (noise.lfsr >> 1)) & 1);
if (noise.lfsr_width == LfsrWidth.LFSR_WIDTH_7)
{
noise.lfsr =
(ushort)(((noise.lfsr >> 1) & ~0x40) | (bit << 6));
}
else
{
noise.lfsr =
(ushort)(((noise.lfsr >> 1) & ~0x4000) | (bit << 14));
}
noise.sample = (byte)(~noise.lfsr & 1);
noise.ticks = noise.period;
}
else
{
frames = total_frames;
noise.ticks -= (uint)frames * APU_TICKS;
}
}
else
{
frames = total_frames;
}
channel4.accumulator += sample * (uint)frames;
total_frames = (int)(total_frames - frames);
}
}
}
