public string GeffeGenerator(int len)
{
string result = "";
for (int i = 0; i < len; i++)
{
bool reg1 = lfsr1.Shift();
bool reg2 = lfsr2.Shift();
bool reg3 = lfsr3.Shift();
bool bit = (reg1 & reg2) ^ (!reg2 & reg3);
result += bit ? "1" : "0";
}
return(result);
}
//////////////////////////////////////////////////////////////////////
//
//////////////////////////////////////////////////////////////////////
public void Update()
{
// called @ 512Hz
m_tick++;
byte b = 0;
double curTime = m_curTime;
byte nr41 = GameBoy.Ram.ReadByteAt(m_nrx1Adr);
byte nr42 = GameBoy.Ram.ReadByteAt(m_nrx2Adr);
byte nr43 = GameBoy.Ram.ReadByteAt(m_nrx3Adr);
byte nr44 = GameBoy.Ram.ReadByteAt(m_nrx4Adr);
b = GameBoy.Ram.ReadByteAt(m_nrx4Adr);
if ((b & 0x80) != 0)
{
m_isConsecutive = (nr44 & 0x40) == 0;
m_curTime = 0;
m_enveloppeClockCnt = 0;
m_initialVol = (nr42 & 0xF0) >> 4;
m_curVol = m_initialVol;
UpdateNR52Flag(true);
b &= 0x7F;
GameBoy.Ram.WriteByte(m_nrx4Adr, b);
}
//length is update at 256Hz (2 cycles)
if (m_tick % 2 == 0)
{
m_lengthSec = nr41 & 0x3F;
m_lengthSec = (64.0 - m_lengthSec) * (1.0 / 256.0);
m_remainingTime = m_lengthSec - m_curTime;
m_polynomialShiftClockFrequency = (nr43 & 0xF0) >> 4;
m_polynomialCounterStep = (nr43 & 0x08) >> 3;
m_polynomialDividerRatio = (nr43 & 0x03);
}
//enveloppe is updated at 64Hz (8 cycles)
if (m_tick % 8 == 0)
{
m_enveloppeClockCnt++;
m_bAttenuate = (nr42 & 0x8) == 0;
m_numberVolumeSweep = (nr42 & 0x7);
m_volLeft = (float)GetCurrentVol(curTime, eChannel.eChannel_Left);
m_volRight = (float)GetCurrentVol(curTime, eChannel.eChannel_Right);
}
int divider = 0;
switch (m_polynomialDividerRatio)
{
case 0: { divider = 8 / 8; break; }
case 1: { divider = 16 / 8; break; }
case 2: { divider = 32 / 8; break; }
case 3: { divider = 48 / 8; break; }
case 4: { divider = 64 / 8; break; }
case 5: { divider = 80 / 8; break; }
case 6: { divider = 96 / 8; break; }
case 7: { divider = 112 / 8; break; }
default: { divider = 0; break; }
}
if (m_tick % divider == 0)
{
m_Lfsr.Shift();
}
double duration = 1.0 / 512.0;
int nbSamplesToFill = (int)(duration * WaveFormat.SampleRate * 2);
double dt = duration / (nbSamplesToFill / 2);
int bufferPos = m_bufferWritingPos;
float f = 0.0f;
for (int n = 0; n < nbSamplesToFill; n += 2)
{
if (m_isConsecutive || curTime < m_lengthSec)
{
f = GetLfsrValue();
}
else
{
f = 0.0f;
UpdateNR52Flag(false);
}
m_buffer[bufferPos] = m_volLeft * f * MAX_AMPLITUDE;
//m_wr.WriteSample(m_volLeft * frequency);
bufferPos++;
if (bufferPos >= m_buffer.Length)
{
bufferPos = 0;
}
m_buffer[bufferPos] = m_volRight * f * MAX_AMPLITUDE;
//m_wr.WriteSample(m_volRight * frequency);
bufferPos++;
if (bufferPos >= m_buffer.Length)
{
bufferPos = 0;
}
curTime += dt;
}
m_bufferWritingPos += nbSamplesToFill;
m_bufferWritingPos %= m_buffer.Length;
m_curTime += duration;
//m_wr.Flush();
}