Akso - Audio DSP Platform

allBiqModes

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This filter is build up from 2 biquad allpass filters. Depending on how they're summed/subtracted (side knobs) a LP, HP (invert knob), BP, lowshelf and highshelf filter can be created

Author: Remco van der Most

License: BSD

Github: sss/filter/allBiqModes.axo

Inlets

frac32buffer in

frac32 center

frac32 width

frac32 side1

frac32 side2

frac32 invert

Outlets

frac32buffer noise

Parameters

frac32.u.map center

frac32.s.map width

frac32.s.map side1

frac32.s.map side2

frac32.s.map invert

Declaration

int32_t All;
int32_t bs[2][2];
int32_t Frq[2];
int32_t ALLPASS(int32_t in, int I) {
  bs[I][1] =
      ___SMMUL(-in << 1, Frq[I]) + bs[I][0] + ___SMMUL(bs[I][1] << 1, Frq[I]);
  All = bs[I][1];
  bs[I][0] = in;
}
int32_t noise;
uint32_t v27 = 1 << 27;

Init

noise = 0;

Control Rate

int32_t center = param_center + inlet_center;
int32_t width = param_width + inlet_width;

SINE2TINTERP(__SSAT(v27 - center - width, 28) << 3, Frq[0])
SINE2TINTERP(__SSAT(v27 - center + width, 28) << 3, Frq[1])
int32_t inv = __SSAT(param_invert + inlet_invert, 28);
int32_t side1 = __SSAT(param_side1 + inlet_side1, 28);
int32_t side2 = __SSAT(param_side2 + inlet_side2, 28);

Audio Rate

noise = inlet_in;
int32_t NS = noise;
ALLPASS(noise, 0);
if (side1 > 0) {
  noise = noise + (___SMMUL(side1, (noise - All >> 1) - noise) << 5);
} else {
  noise = noise + (___SMMUL(side1, -(noise + All >> 1) + noise) << 5);
}

ALLPASS(noise, 1);
if (side2 > 0) {
  noise = noise + (___SMMUL(side2, (noise - All >> 1) - noise) << 5);
} else {
  noise = noise + (___SMMUL(side2, -(noise + All >> 1) + noise) << 5);
}

int32_t ns = noise - ___SMMUL(inv << 3, NS << 2);
outlet_noise = ns;

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