bppSVF
3x 2-pole resonant filters (SVF) 1 LP and 1 HP to create a band-width-controllable BP filter and a 3rd filter in BP mode which is added as an extra peak inside the set band ("center" cutoff range is normalised to bandwidth of LP and HP filters).
Inlets
frac32buffer in
frac32 cutoff
frac32 reso
frac32 center
frac32 width
Outlets
frac32buffer out
Parameters
frac32.s.map.pitch cutoff
frac32.s.map center
frac32.s.map peak
frac32.u.map width
frac32.u.map.filterq resoHP
frac32.u.map.filterq resoLP
frac32.u.map.filterq resoPeak
int32_t out;
int32_t low[3];
int32_t band[3];
int32_t notch;
int32_t high;
int32_t freq[3];
int32_t res[3];
int32_t COEF(int32_t F, int32_t R, int I) {
res[I] = (0x80 << 24) - (R << 4);
res[I] = ___SMMUL(res[I], res[I]);
int32_t alpha;
MTOFEXTENDED(F, alpha);
SINE2TINTERP(alpha, freq[I]);
}
int32_t SVF(int32_t IN, int I) {
band[I] -= ___SMMUL(___SMMUL(band[I] << 2, band[I] << 2), band[I] << 2);
notch = IN - (___SMMUL(res[I], band[I]) << 1);
low[I] = low[I] + (___SMMUL(freq[I], band[I]) << 1);
high = notch - low[I];
band[I] = (___SMMUL(freq[I], high) << 1) + band[I];
}
int32_t SOFT(int32_t in) {
int32_t ts = __SSAT(in, 28);
int32_t tsq31 = ts << 3;
int32_t tsq31p3 = ___SMMUL(tsq31, ___SMMUL(tsq31, tsq31));
return out = ts + (ts >> 1) - (tsq31p3);
}int32_t width = __SSAT(inlet_width + param_width, 28);
int32_t cutoff = param_cutoff + inlet_cutoff;
COEF(__SSAT(cutoff +
(___SMMUL(__SSAT(param_center + inlet_center, 28), width) << 5),
28),
param_resoPeak, 0);
COEF(__SSAT(cutoff + width, 28), param_resoLP, 1);
COEF(__SSAT(cutoff - width, 28), param_resoHP, 2);SVF(inlet_in >> 1, 0);
SVF(SOFT((inlet_in >> 1) + (___SMMUL(band[0], param_peak << 4) << 1)), 1);
SVF(SOFT(low[1]), 2);
outlet_out = SOFT(high);