static const uint32_t LENGTHPOW = (attr_size);
static const uint32_t LENGTH = (1 << attr_size);
static const uint32_t LENGTHMASK = ((1 << attr_size) - 1);
static const uint32_t MINDD = (32 << (27 - LENGTHPOW));
static const uint32_t MAXDD = (1 << 27) - (32 << (27 - LENGTHPOW));
int32_t *d;

int32_t interp(uint32_t ind, int32_t p) {
  // int32_t a = p&((1<<(27-LOG2))-1); //q27-LOG2
  // a <<= 31-(27-LOG2); //q31
  int32_t a = (p << (31 - (27 - LENGTHPOW))) & 0x7FFFFFFF; // q31
  int32_t i = p >> (27 - LENGTHPOW);                       // int
  i = (ind + i) & LENGTHMASK;
  int32_t d0 = d[i];
  return ___SMMLA(a, (d[(i + 1) & LENGTHMASK] - d0) << 1, d0);
}
void calcOut(int32_t in_d, int32_t &d, int32_t &fd, int32_t *out) {
  // local copies -> registers
  int32_t ld = d;
  int32_t lfd = fd;

  int i = ind;
  int32_t dd = in_d;
  if (dd < MINDD)
    dd = MINDD;
  else if (dd > MAXDD)
    dd = MAXDD;

  dd = (dd - ld) >> 4;
  for (int smp = 0; smp < BUFSIZE; smp++) {
    ld += dd;                                  // interpolation
    lfd = ___SMMLA(0x10000000, ld - lfd, lfd); // smooth
    out[smp] = interp(i, lfd);
    i -= 2;
    i &= LENGTHMASK;
  }
  d = ld;
  fd = lfd;
}
uint32_t ind;
int32_t x, y;
int32_t d1, fd1, d2, fd2, d3, fd3, d4, fd4, d5, fd5;

float x0, x1, x2, x3, x4, x5, y0, y1;

static int32_t _d[attr_poly][1 << attr_size] __attribute__((section(".sdram")));
d = &_d[parent->polyIndex][0];

for (int i = 0; i < LENGTH; i++)
  d[i] = 0;
ind = 0;
d1 = fd1 = d2 = fd2 = d3 = fd3 = d4 = fd4 = d5 = fd5 = x = y = 0;
x0 = x1 = x2 = x3 = x4 = x5 = y0 = y1 = 0;

// writer
if (attr_Over == 1) {
  for (int smp = 0; smp < BUFSIZE; smp++) {
    // interp -> LP1
    ind--;
    ind &= LENGTHMASK;
    d[ind] = y = (((inlet_in[smp] + x) >> 1) + y) >> 1;
    // nointerp ->LP1
    x = inlet_in[smp];
    ind--;
    ind &= LENGTHMASK;
    d[ind] = y =
        ___SMMLA(1004378102, x - y,
                 y); // 0.4677q31 same gain as one zero one pole 0.5 at Sr/8
  }
}
if (attr_Over == 2) {
  for (int smp = 0; smp < BUFSIZE; smp++) {
    ind--;
    ind &= LENGTHMASK;
    d[ind] = inlet_in[smp];
    ind--;
    ind &= LENGTHMASK;
    d[ind] = inlet_in[smp];
  }
}
// use interpolator
if (attr_Over == 3) {
  for (int smp = 0; smp < BUFSIZE; smp++) {
    x0 = x1;
    x1 = x2;
    x2 = x3;
    x3 = x4;
    x4 = x5;
    x5 = (float)inlet_in[smp];
    /*outlet_y1 = (int32_t)x2;
    outlet_y0 = (int32_t)(
             (x5 + x0) * 0.025665914601895386f
         + (x4 + x1) * -0.04277652433649233f
         + (x3 + x2) * 0.517110609734597f
         );
            */
    ind--;
    ind &= LENGTHMASK;
    d[ind] = (int32_t)x2;
    ind--;
    ind &= LENGTHMASK;
    d[ind] = (int32_t)((x5 + x0) * 0.025665914601895386f +
                       (x4 + x1) * -0.04277652433649233f +
                       (x3 + x2) * 0.517110609734597f);
  }
}
// _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
// readers
calcOut(inlet_d1, d1, fd1, outlet_out1);
calcOut(inlet_d2, d2, fd2, outlet_out2);
calcOut(inlet_d3, d3, fd3, outlet_out3);
calcOut(inlet_d4, d4, fd4, outlet_out4);
calcOut(inlet_d5, d5, fd5, outlet_out5);