bppBIQ
3x 2-pole resonant filters (biquad) 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). Uses "object oriënted" coding, allowing the user to easily create his own filter. If you want to add more filters, don't forget to add buffers for each extra filter: as shown in local data-> int32_t tmp1[BUFSIZE] for the first filter)
Inlets
frac32buffer filter input
frac32 pitch
frac32 filter resonance
frac32 center
frac32 width
Outlets
frac32buffer filter output
Parameters
frac32.u.map.filterq resoHP
frac32.u.map.filterq resoLP
frac32.u.map.filterq resoC
frac32.u.map.gain peak
frac32.s.map.pitch cutoff
frac32.s.map center
frac32.u.map width
biquad_state bs[3];
biquad_coefficients bc[3];
int32_t tmp1[BUFSIZE];
int32_t tmp2[BUFSIZE];
int32_t tmp3[BUFSIZE];
int i;for (i = 0; i < 3; i++) {
biquad_clearstate(&bs[i]);
}int32_t freq;
int32_t width = __SSAT(inlet_width + param_width, 28);
MTOF(param_cutoff + inlet_pitch +
___SMMUL(param_center + inlet_center << 2, width << 3),
freq);
biquad_bp_coefs(&bc[0], freq,
INT_MAX - (__USAT(inlet_reso + param_resoC, 27) << 4));
biquad_dsp(&bs[0], &bc[0], inlet_in, tmp1);
for (i = 0; i < BUFSIZE; i++) {
tmp1[i] = __SSAT(inlet_in[i], 28) +
(___SMMUL(__SSAT(tmp1[i], 28), param_peak) << 2);
}
MTOF(param_cutoff - width + inlet_pitch, freq);
biquad_hp_coefs(&bc[1], freq,
INT_MAX - (__USAT(inlet_reso + param_resoHP, 27) << 4));
biquad_dsp(&bs[1], &bc[1], tmp1, tmp2);
MTOF(param_cutoff + width + inlet_pitch, freq);
biquad_lp_coefs(&bc[2], freq,
INT_MAX - (__USAT(inlet_reso + param_resoLP, 27) << 4));
biquad_dsp(&bs[2], &bc[2], tmp2, outlet_out);