float buf1;
float buf2;
float buf3;
float buf4;
float resoclip;
float in;

// Cut off param + input
int32_t CutOff = inlet_c + param_Cut;

// Use math/exp to scale cut off
int32_t EXP;
int8_t s = (CutOff >> 24) + 4;
uint8_t ei = CutOff >> 16;
if (s >= 0)
  EXP = expt[ei] << s;
else
  EXP = expt[ei] >> (-s);

// Set minimum value for cut off to 0.25
int32_t MinimumCut = (EXP > (0.25f * (1 << 21))) ? EXP : (0.25f * (1 << 21));
// Set maximum value for cut off
int32_t MaximumCut =
    (MinimumCut < 1 + (64 << 21)) ? MinimumCut : 1 + (64 << 21);
// Set range of cut off to around 0.8
int32_t CutOffRange =
    ___SMMUL(MaximumCut << 3, (int32_t)(0.8149995803833008f * (1 << 21)) << 2);

// Resonance param + input
int32_t Reso = inlet_r + param_Res;
// Set maximum value for resonance
int32_t MaximumRes = (Reso < 1 + (64 << 21)) ? Reso : 1 + (64 << 21);
// Set range of resonance to 4
int32_t ResoRange = ___SMMUL(MaximumRes << 3, 1 + (4 << 21) << 2);

// Convert int32_t parameters to float
float cut = arm::q_to_float(CutOffRange, 21);
float res = arm::q_to_float(ResoRange, 21);

/*
The parameters are:
b_cut - cutoff freq
b_rez - resonance
b_in1 - input

resoclip = buf4; if (resoclip > 1) resoclip = 1;
in = in - (resoclip * res);
buf1 = ((in - buf1) * cut) + buf1;
buf2 = ((buf1 - buf2) * cut) + buf2;
buf3 = ((buf2 - buf3) * cut) + buf3;
buf4 = ((buf3 - buf4) * cut) + buf4;
lpout = buf4;

Note that asymmetrical clipping gives you DC offset (at least that's what I
get), so symmetrical clipping is better (and gives a much smoother sound).

*/

// Input as float value
float input = arm::q_to_float(inlet_i, 21);

// Karlsen 24db fast ladder filter
resoclip = buf4;
if (resoclip > 1 + (64 << 21))
  resoclip = 1 + (64 << 21);
in = input - (resoclip * res);
buf1 = ((in - buf1) * cut) + buf1;
buf2 = ((buf1 - buf2) * cut) + buf2;
buf3 = ((buf2 - buf3) * cut) + buf3;
buf4 = ((buf3 - buf4) * cut) + buf4;

// Convert float back to int32_t
outlet_o = (int32_t)(buf4 * (1 << 21));