void Bandpass::pull(AudioChunk &chunk,
const Bandpass_Node &a, const Bandpass_Node &b)
{
//Pull source data
source.pull(chunk);
//Calculate RC multipliers
float
al = RCCONV / ((a.low<=0.0f)?40000.0f:a.low),
ah = RCCONV / ((a.high<=0.0f)?10.0f:a.high),
bl = RCCONV / ((b.low<=0.0f)?40000.0f:b.low),
bh = RCCONV / ((b.high<=0.0f)?10.0f:b.high);
float lpRC = al, hpRC = ah,
lpM = pow(bl/al, 1.0f / float(chunk.length())),
hpM = pow(bh/ah, 1.0f / float(chunk.length())),
lpA, hpA, samp,
dt = 1.0f / float(chunk.format().rate);
//Apply effect!
Uint32 chan = source.format().channels;
for (Uint32 i = 0; i < chan; ++i)
{
Sint32 *pos = chunk.start(i), *end = chunk.end(i);
float &lpPc = lpP[i], &hpDc = hpD[i];
while (pos < end)
{
//Interpolate settings
lpA = dt / (lpRC + dt); lpRC *= lpM;
hpA = hpRC / (hpRC + dt); hpRC *= hpM;
//Get samples
samp = float(*pos);
//Lowpass
samp = lpPc + lpA * (samp-lpPc);
lpPc = samp;
//Highpass (confusing but correct)
samp = hpA * (samp+hpDc);
hpDc = samp - lpPc;
//Set samples
*pos = Sint32(samp);
++pos;
}
}
}
void Oscillator::pull(AudioChunk &chunk, const State &a, const State &b)
{
//Phase goes from -1 to 1. Wierd? Maybe.
while (phase >= 1.0f) phase -= 2.0f;
while (phase < -1.0f) phase += 2.0f;
Sint32 samp;
float v, x, sq;
float step = (b.freq / output.rate) * 2.0f,
amp = b.amp * 16777215.0f,
ph = phase;
Sint32 *i = chunk.start(0), *e = chunk.end(0);
switch (type)
{
case SINE:
while (i != e)
{
//Simple sine wave
samp = amp*sin(PI * ph);
ph += step;
*i = samp; ++i;
ph -= 2.0f*int(ph*.5f); //Restrict to [-1, 1]
}
break;
case SQUARE:
while (i != e)
{
samp = amp * ((ph>=0.0f) ? 1.0f : -1.0f);
ph += step;
*i = samp; ++i;
ph -= 2.0f*int(ph*.5f); //Restrict to [-1, 1]
}
break;
case TRIANGLE:
while (i != e)
{
samp = amp * (2.0f*std::abs(ph) - 1.0f);
ph += step;
*i = samp; ++i;
ph -= 2.0f*int(ph*.5f); //Restrict to [-1, 1]
}
break;
case SAWTOOTH:
while (i != e)
{
samp = amp * ph;
ph += step;
*i = samp; ++i;
ph -= 2.0f*int(ph*.5f); //Restrict to [-1, 1]
}
break;
case KLAXON:
default:
{
const float PISQ = PI*PI;
while (i != e)
{
//Sine wave approximation gone wrong
sq = PISQ*ph*ph; x = PI*ph*amp;
v = x * 1.02394347; //Makes the endpoints line up
x *= sq; v -= x/6.0f;
x *= sq; v += x/120.0f;
x *= sq; v -= x/5040.0f;
samp = x;
ph += step;
*i = samp; ++i;
ph -= 2.0f*int(ph*.5f); //Restrict to [-1, 1]
}
}
break;
}
phase = ph;
//Copy signal into all other channels
for (Uint32 c = chunk.channels()-1; c > 0; --c)
{
std::memcpy(chunk.start(c), chunk.start(0), 4*chunk.length());
}
}
