private static int SquareFill(ToneChannel ch, short[] buffer, int index, int count)
{
if (ch.GenType != ch.GenTypePrev)
{
ch.FreqCountPrev = -1;
ch.Noise.Sign = 1;
ch.GenTypePrev = ch.GenType;
}
if (ch.FreqCount != ch.FreqCountPrev)
{
ch.Noise.Scale = (44100 / 2) * ch.FreqCount;
ch.Noise.Count = ch.Noise.Scale;
ch.FreqCountPrev = ch.FreqCount;
}
for (int i = index; i < (index + count); i++)
{
buffer[i] = (ch.Noise.Sign != 0) ? VolumeTable[ch.Attenuation] : (short)(0 - VolumeTable[ch.Attenuation]);
// get next sample
ch.Noise.Count -= Mult;
while (ch.Noise.Count <= 0)
{
ch.Noise.Sign ^= 1;
ch.Noise.Count += ch.Noise.Scale;
}
}
return(count);
}
private static int NoiseFill(ToneChannel ch, short[] buffer, int index, int count)
{
if (ch.GenType != ch.GenTypePrev)
{
ch.FreqCountPrev = -1;
ch.GenTypePrev = ch.GenType;
}
if (ch.FreqCount != ch.FreqCountPrev)
{
ch.Noise.Scale = (44100 / 2) * ch.FreqCount;
ch.Noise.Count = ch.Noise.Scale;
ch.FreqCountPrev = ch.FreqCount;
ch.Noise.Feedback = ch.GenType == GenerateWhite ? FeedbackWhiteNoise : FeedbackPeriodicNoise;
// reset noise shifter
ch.Noise.NoiseState = NoiseGeneratorStartPreset;
ch.Noise.Sign = (int)(ch.Noise.NoiseState & 1);
}
for (int i = index; i < (index + count); i++)
{
buffer[i] = (ch.Noise.Sign != 0) ? VolumeTable[ch.Attenuation] : (short)(0 - VolumeTable[ch.Attenuation]);
// get next sample
ch.Noise.Count -= Mult;
while (ch.Noise.Count <= 0)
{
if ((ch.Noise.NoiseState & 1) != 0)
{
ch.Noise.NoiseState ^= (uint)ch.Noise.Feedback;
}
ch.Noise.NoiseState >>= 1;
ch.Noise.Sign = (int)(ch.Noise.NoiseState & 1);
ch.Noise.Count += ch.Noise.Scale;
}
}
return(count);
}
int ISoundDriver.Open(int channel)
{
ToneChannel tc = new ToneChannel();
tc.Attenuation = 0xf; // silence
tc.AgiChannel = channel;
tc.FreqCount = 250;
tc.FreqCountPrev = -1;
tc.GenType = GenerateTone;
tc.GenTypePrev = -1;
tc.NoteCount = 0;
tc.Avail = 1;
this.channels.Add(tc);
tc.Handle = this.pcmDriver.Open(this.TonePcmCallback, tc);
if (tc.Handle == 0)
{
this.channels.Remove(tc);
return(0);
}
return(tc.Handle);
}
private int TonePcmCallback(ToneChannel ch, short[] buffer, int count)
{
int result = -1;
int index = 0;
while (count > 0)
{
if (ch.NoteCount <= 0)
{
// Get new tone data
Tone tone = new Tone();
tone.FrequencyCount = 0;
tone.Attenuation = 0x0f;
tone.Type = GenerateTone;
if (ch.Avail != 0 && this.interpreter.SoundManager.FillChannel(ch.AgiChannel, tone) == 0)
{
ch.Attenuation = tone.Attenuation;
ch.FreqCount = tone.FrequencyCount;
ch.GenType = tone.Type;
// setup counters 'n stuff
// 44100 samples per sec.. tone changes 60 times per sec
ch.NoteCount = 44100 / 60;
result = 0;
}
else
{
ch.GenType = GenerateSilence;
ch.NoteCount = count;
ch.Avail = 0;
}
}
// Write nothing
if (ch.FreqCount == 0 || ch.Attenuation == 0x0f)
{
ch.GenType = GenerateSilence;
}
// Find which is smaller, the buffer or the note count
int fillSize = ch.NoteCount < count ? ch.NoteCount : count;
switch (ch.GenType)
{
case GenerateTone:
fillSize = PcmSoundDriver.SquareFill(ch, buffer, index, fillSize);
break;
case GeneratePeriod:
case GenerateWhite:
fillSize = PcmSoundDriver.NoiseFill(ch, buffer, index, fillSize);
break;
case GenerateSilence:
default:
fillSize = PcmSoundDriver.SilenceFill(buffer, index, fillSize);
break;
}
ch.NoteCount -= fillSize;
count -= fillSize;
index += fillSize;
}
return(result);
}
