DP type IIA
type IIA distortion with Differentiated Rational Function Anti aliasing.
Inlets
frac32buffer.bipolar in
frac32 factor
frac32 offset
Outlets
frac32buffer out
Parameters
frac32.s.map offset
frac32.u.map factor
Declaration
float x0, v0, x1, y0, y1;
Init
v0 = 0;
Control Rate
float factor = __USAT(param_factor + inlet_factor, 27) * (6.0f / (1 << 27));
float offset = __SSAT(param_offset + inlet_offset, 28) * (1.5f / (1 << 27));
// update according to new values
x0 = factor * (offset + v0);
y0 = 1.5f * x0 * x0 / (1 + x0 * x0);
// Integ x^-2 dx = -x^-1 = -1/x
for (int i = 0; i < BUFSIZE; i++) {
x1 = x0;
y1 = y0;
x0 = factor * (offset + (v0 = arm::q_to_float(__SSAT(inlet_in[i], 28), 27)));
float dx = x1 - x0;
if (fabs(dx) > 0.005f) {
y0 = 1.5f * x0 * x0 / (1 + x0 * x0);
float dy = y1 - y0;
outlet_out[i] = arm::float_to_q(dy / dx, 27);
} else {
float inv = 1 / (1 + x0 * x0);
y0 = 1.5f * x0 * x0 * inv;
outlet_out[i] = arm::float_to_q(3 * x0 * inv * inv, 27);
}
}