public PSG(CDRom cdrom)
{
m_Channels = new PSG_Channel[8];
for (int i = 0; i < 8; i++)
{
m_Channels[i] = new PSG_Channel();
m_Channels[i].m_Buffer = new int[32];
m_Channels[i].m_BufferIndex = 0;
}
m_Selected = m_Channels[0];
m_CDRom = cdrom;
StartMixer(44100, 1024);
}
public void Write(int address, byte data)
{
switch (address)
{
// Global audio registers
case 0x800:
m_Selected = m_Channels[data & 0x07];
break;
case 0x801:
m_Left_Volume = (data >> 4);
m_Right_Volume = (data & 0x0F);
break;
case 0x808:
m_LFO_Frequency = data;
break;
case 0x809:
m_LFO_Enabled = (data & 0x80) != 0;
switch (data & 0x3)
{
case 0:
m_LFO_Active = false;
break;
case 1:
m_LFO_Active = true;
m_LFO_Shift = 0;
break;
case 2:
m_LFO_Active = true;
m_LFO_Shift = 4;
break;
case 3:
m_LFO_Active = true;
m_LFO_Shift = 8;
break;
}
if (m_LFO_Enabled && m_LFO_Active)
{
Console.WriteLine("LFO MODE HAS BEEN ACTIVATED");
}
break;
// Per Channel Registers
case 0x802:
m_Selected.m_Frequency = (m_Selected.m_Frequency & 0x0F00) | data;
break;
case 0x803:
m_Selected.m_Frequency = (m_Selected.m_Frequency & 0x00FF) | ((data << 8) & 0x0F00);
break;
case 0x804:
m_Selected.m_Enabled = (data & 0x80) != 0;
m_Selected.m_DDA = (data & 0x40) != 0;
m_Selected.m_Volume = data & 0x0F;
break;
case 0x805:
m_Selected.m_Left_Volume = (data >> 4);
m_Selected.m_Right_Volume = (data & 0x0F);
break;
case 0x806:
m_Selected.m_DDA_Output = data & 0x1F;
m_Selected.m_Buffer[m_Selected.m_BufferIndex] = (data & 0x1F) - 0x10;
m_Selected.m_BufferIndex = (m_Selected.m_BufferIndex + 1) & 0x1F;
break;
case 0x807:
m_Selected.m_Noise = ((data & 0x80) != 0);
m_Selected.m_NoiseFrequency = (data & 0x1F ^ 0x1F);
m_Selected.m_RealNoiseFrequency = 112005.0f / m_SampleRate / (m_Selected.m_NoiseFrequency + 1);
break;
default:
Console.WriteLine("PSG Access at {0:x} -> {1:x}", address, data);
break;
}
for (int i = 0; i < 6; i++)
{
PSG_Channel channel = m_Channels[i];
channel.m_RealFrequency = 3584160.0f / m_SampleRate / (channel.m_Frequency + 1);
channel.m_LeftOutput = m_VolumeTable[(channel.m_Left_Volume + m_Left_Volume) * 2 + channel.m_Volume];
channel.m_RightOutput = m_VolumeTable[(channel.m_Right_Volume + m_Right_Volume) * 2 + channel.m_Volume];
if (i < 4)
{
channel.m_Noise = false;
}
}
m_RealLFOFrequency = 3584160.0f / m_SampleRate / ((m_Channels[1].m_Frequency + 1) * m_LFO_Frequency);
}
public unsafe void audioCallback(void *userdata, void *buffer, int len)
{
short *stream = (short *)buffer;
int i, c;
len /= 2;
for (i = 0; i < len; i += 2)
{
float left = 0;
float right = 0;
if (m_LFO_Enabled && m_LFO_Active)
{
PSG_Channel channel = m_Channels[1];
int LFOFreq = channel.m_Buffer[(int)channel.m_OutputIndex];
channel.m_OutputIndex += m_RealLFOFrequency;
while (channel.m_BufferIndex >= 32)
{
channel.m_BufferIndex -= 32;
}
// Sign extend the frequency
if ((LFOFreq & 0x10) != 0)
{
LFOFreq |= -16;
}
channel = m_Channels[0];
channel.m_RealFrequency = 3584160.0f / m_SampleRate / (channel.m_Frequency + (LFOFreq << m_LFO_Shift) + 1);
}
for (c = 0; c < 6; c++)
{
PSG_Channel channel = m_Channels[c];
// LFO disables channel 1
if (!channel.m_Enabled || (m_LFO_Enabled && c == 1))
{
continue;
}
int sample;
if (channel.m_DDA)
{
sample = channel.m_DDA_Output;
}
else if (channel.m_Noise)
{
sample = m_NoiseBuffer[(int)channel.m_NoiseIndex];
channel.m_NoiseIndex += channel.m_RealFrequency;
while (channel.m_NoiseIndex >= 0x8000)
{
channel.m_NoiseIndex -= 0x8000;
}
}
else
{
sample = channel.m_Buffer[(int)channel.m_OutputIndex];
channel.m_OutputIndex += channel.m_RealFrequency;
while (channel.m_OutputIndex >= 32)
{
channel.m_OutputIndex -= 32;
}
}
left += sample * channel.m_LeftOutput;
right += sample * channel.m_RightOutput;
}
*(stream++) = (short)(right + m_BaseLine);
*(stream++) = (short)(left + m_BaseLine);
}
m_CDRom.MixCD((short *)buffer, len * 2);
}
