int32_t sin2t_q27(uint32_t p) {
  int32_t a = (p & ((1 << 20) - 1)) << 8; // q28
  uint32_t i = p >> 20;
  return ___SMMLA(a, sine2t[i + 1] - sine2t[i], sine2t[i] >> 4);
}
int32_t cos2t_q27(uint32_t p) { return sin2t_q27(p + (1UL << 30)); }
int32_t d[256];
uint8_t dc;
int32_t in_i;
int32_t in_mod;
int32_t modI, modR, theta;
int32_t a_r;
int32_t signalLPCoeff, signalLP;
int32_t modLPCoeff, modLP;
int32_t HPCoeff, hp;

for (int i = 0; i < 256; i++)
  d[i] = 0;
dc = 0;
in_i = 0;
in_mod = 0;
modI = 0;
modR = 0;
theta = 1 << 28;
a_r = 0;
signalLPCoeff = 1 << 28;
signalLP = 0;
modLPCoeff = 1 << 28;
modLP = 0;
HPCoeff = 1 << 28;
hp = 0;

int32_t cutoff = param_signal_space_LP + inlet_signal_space_LP;
if (cutoff > 64 << 21)
  cutoff = 64 << 21;
int32_t nSignalLPCoeff;
MTOFEXTENDED(cutoff, nSignalLPCoeff);

cutoff = param_mod_space_LP + inlet_mod_space_LP;
if (cutoff > 64 << 21)
  cutoff = 64 << 21;
int32_t nModLPCoeff;
MTOFEXTENDED(cutoff, nModLPCoeff);

int signalDelay = param_signal_space_fb_space_delay - 1;
int modDelay = param_mod_space_fb_space_delay - 1;

cutoff = param_HP + inlet_HP;
if (cutoff > 64 << 21)
  cutoff = 64 << 21;
int32_t nHPCoeff;
MTOFEXTENDED(cutoff, nHPCoeff);
// deltas for linear interpolations at audio rate
int32_t dSignalLPCoeff = (nSignalLPCoeff - signalLPCoeff) >> 4;
int32_t dModLPCoeff = (nModLPCoeff - modLPCoeff) >> 4;
int32_t dHPCoeff = (nHPCoeff - HPCoeff) >> 4;
int32_t nModI = param_mod_space_i + inlet_mod_space_i;
int32_t nModR = param_mod_space_r + inlet_mod_space_r;
int32_t dTheta = (param_theta + inlet_theta_space_kr - theta) >> 4;
// jump
if (abs(dTheta) > (1 << 19)) {
  theta = param_theta + inlet_theta_space_kr;
  dTheta = 0;
}

// update modulation depth on zero crossings to avoid clics
if (a_r > 0 != inlet_r > 0)
  modR = nModR;
a_r = inlet_r;

// linear interpolation of krate theta
theta += dTheta;

// calc of modulated rotation angle
uint32_t a = theta;
a += ___SMMLA(in_mod, modI, ___SMMUL(inlet_r, modR)) << 6;
a += inlet_theta_space_ar;
a &= 0x07FFFFFF;
a <<= 5;

int32_t c = cos2t_q27(a);
int32_t s = sin2t_q27(a);
outlet_r = ___SMMLS(in_i, s, ___SMMUL(inlet_r, c)) << 5;
outlet_i = ___SMMLA(in_i, c, ___SMMUL(inlet_r, s)) << 5;

// feedback HP filter
hp = ___SMMLA(HPCoeff += dHPCoeff, (outlet_i - hp) << 1, hp);

// delay input
// (hp is actually 'outlet_i - hp')
dc--;
d[dc] = outlet_i - hp;

// feedback signal: delay and low pass
signalLP = ___SMMLA(signalLPCoeff += dSignalLPCoeff,
                    (d[(uint8_t)(dc + signalDelay)] - signalLP) << 1, signalLP);
signalLP = __SSAT(signalLP, 29);
in_i = signalLP;

// feedback modulation: delay and lowpass
modLP = ___SMMLA(modLPCoeff += dModLPCoeff,
                 (d[(uint8_t)(dc + modDelay)] - modLP) << 1, modLP);

// update modulation depth on zero crossings to avoid clics
if (in_mod > 0 != modLP > 0)
  modI = nModI;
in_mod = modLP;