MMAP
Multimode filter based on two allpass filters, functioning as poles for the filter. Depending on the modes of the filters and (bipolar) mix amount, LP, BP, HP, NOTCH, HIGHSHELF, LOWSHELF and PEAK filters can be created and morphed into each other. As the basis is an allpass filter, the cutoff frequency will fold back if it goes over 64 or below 0. This can change the filter type as well as peak width.
Inlets
frac32buffer i1
frac32 cut
frac32 width
Outlets
frac32buffer o1
Parameters
frac32.u.map main cutoff frequency
frac32.u.map poles frequency spread
frac32.s.map scales the amount of modulation of the cutoff frequency
frac32.s.map scales negative part of modulation for normal/half-wave-rectification/abs
frac32.s.map amount of filter resonance
frac32.s.map mixes the filtered signal with the original: left is addition (eg. peak,notch, shelfs), right is subtraction (eg. LP,BP,HP)
frac32.s.map morphs pole 1 from LP through BP to HP
frac32.s.map morphs pole 2 from LP through BP to HP
int32_t All;
int32_t bs[4][2];
uint32_t v30 = 1 << 30;
uint32_t v27 = 1 << 27;
int32_t ALLPASS(int32_t in, int32_t pitch, int I) {
int32_t Frq;
SINE2TINTERP(pitch << 3, Frq)
bs[I][1] = ___SMMUL(-in << 1, Frq) + bs[I][0] + ___SMMUL(bs[I][1] << 1, Frq);
All = bs[I][1];
bs[I][0] = in;
}
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 ts = ts + (ts >> 1) - (tsq31p3);
}int32_t mode1 = param_mode1 > 0 ? -param_mode1 : param_mode1;
int32_t mode2 = param_mode2 > 0 ? -param_mode2 : param_mode2;int32_t mod = All + inlet_i1;
mod = ___SMMUL(mod > 0 ? mod : ___SMMUL(mod, -param_abs) << 5, -param_mod) << 3;
ALLPASS(inlet_i1 + (___SMMUL(All, param_resonance) << 5),
v27 - param_cut - (inlet_cut >> 1) + mod, 0);
All =
(___SMMUL(param_mode1, inlet_i1) << 5) + (___SMMUL(mode1, All) << 4) + All;
// All-=(___SMMUL(mode,All)<<3);
int32_t in = All;
ALLPASS(All,
v27 - param_cut - (inlet_cut >> 1) + param_width + inlet_width + mod,
1);
All = (___SMMUL(param_mode2, in) << 4) + (___SMMUL(mode2, All) << 4) + All;
// All-=(___SMMUL(mode,All)<<3);
outlet_o1 = SOFT((inlet_i1) - (___SMMUL(All, param_mix) << 5));
All = __SSAT(-inlet_i1 + All, 28);