src/calf/bypass.h

   1 #ifndef CALF_BYPASS_H
   2 #define CALF_BYPASS_H
   3
   4 #include "inertia.h"
   5
   6 namespace dsp {
   7
   8 class bypass
   9 {
  10     inertia<linear_ramp> ramp;
  11     float first_value, next_value;
  12
  13 public:
  14     bypass(int _ramp_len = 1024)
  15     : ramp(linear_ramp(_ramp_len))
  16     {
  17     }
  18
  19     /// Pass the new state of the bypass button, and return the ramp-aware
  20     /// bypass state
  21     bool update(bool new_state, uint32_t nsamples)
  22     {
  23         ramp.set_inertia(new_state ? 1.f : 0.f);
  24         first_value = ramp.get_last();
  25         ramp.step_many(nsamples);
  26         next_value = ramp.get_last();
  27         return first_value >= 1 && next_value >= 1;
  28     }
  29
  30     /// Apply ramp to prevent clicking
  31     void crossfade(float *inputs[], float *outputs[], uint32_t nbuffers, uint32_t offset, uint32_t nsamples)
  32     {
  33         if (!nsamples || (first_value + next_value) == 0)
  34             return;
  35         float step = (next_value - first_value) / nsamples;
  36         for (uint32_t b = 0; b < nbuffers; ++b)
  37         {
  38             float *out = outputs[b] + offset, *in = inputs[b] + offset;
  39             if (first_value >= 1 && next_value >= 1)
  40                 memcpy(out, in, nsamples * sizeof(float));
  41             else
  42             {
  43                 for (uint32_t i = 0; i < nsamples; ++i)
  44                 {
  45                     float bypass_amt = first_value + i * step;
  46                     out[i] += (in[i] - out[i]) * bypass_amt;
  47                 }
  48             }
  49         }
  50     }
  51 };
  52
  53 }
  54
  55 #endif