Adsr remake

Source/Control/adsr.cpp

@@ -3,79 +3,77 @@
 
 using namespace daisysp;
 
-float Adsr::Tau2Pole(float tau)
+
+void Adsr::Init(float sample_rate, int blockSize)
 {
- return expf(-1.0f / (tau * sample_rate_));
+ sample_rate_ = sample_rate / blockSize;
+ SetTime(ADSR_SEG_ATTACK, 0.1f);
+ SetTime(ADSR_SEG_DECAY, 0.1f);
+ SetTime(ADSR_SEG_RELEASE, 0.1f);
+ sus_level_ = 0.7f;
+ x_ = 0.0f;
 }
 
-float Adsr::AdsrFilter()
+void Adsr::Retrigger(bool hard)
 {
- y_ = b_ * x_ + a_ * y_;
- return y_;
+ mode_ = ADSR_SEG_ATTACK;
+ if(hard)
+ x_ = 0.f;
 }
 
-
-void Adsr::Init(float sample_rate)
+void
+Adsr::SetTime(int seg, float time)
 {
- seg_time_[ADSR_SEG_ATTACK] = 0.1f;
- seg_time_[ADSR_SEG_DECAY] = 0.1f;
- sus_ = 0.7f;
- seg_time_[ADSR_SEG_RELEASE] = 0.1f;
- //timer_ = 0;
- a_ = 0.0f;
- b_ = 0.0f;
- x_ = 0.0f;
- y_ = 0.0f;
- prev_ = 0.0f;
- atk_time_ = seg_time_[ADSR_SEG_ATTACK] * sample_rate;
- sample_rate_ = sample_rate;
+ if(seg_time_[seg] != time)
+ {
+ seg_time_[seg] = time;
+ if(time > 0.f)
+ {
+ const float attackTarget = logf(0.5f);
+ const float decayTarget = logf(1./M_E);
+ float target = (seg == ADSR_SEG_ATTACK)? attackTarget : decayTarget;
+ seg_D0_ [seg] = 1.f - expf(target / (time * sample_rate_));
+ }
+ else
+ seg_D0_ [seg] = 1.f; // instant change
+ }
 }
 
+
 float Adsr::Process(bool gate)
 {
- float pole, out;
- out = 0.0f;
+ float out = 0.0f;
 
  if(gate && mode_ != ADSR_SEG_DECAY)
- {
  mode_ = ADSR_SEG_ATTACK;
- //timer_ = 0;
- pole = Tau2Pole(seg_time_[ADSR_SEG_ATTACK] * 0.6f);
- atk_time_ = seg_time_[ADSR_SEG_ATTACK] * sample_rate_;
- a_ = pole;
- b_ = 1.0f - pole;
- }
  else if(!gate && mode_ != ADSR_SEG_IDLE)
- {
  mode_ = ADSR_SEG_RELEASE;
- pole = Tau2Pole(seg_time_[ADSR_SEG_RELEASE]);
- a_ = pole;
- b_ = 1.0f - pole;
- }
-
- x_ = (int)gate;
- prev_ = (int)gate;
 
+ float D0(seg_D0_[mode_]);
+ float target = mode_ == ADSR_SEG_DECAY? sus_level_ : - 0.1f;
  switch(mode_)
  {
  case ADSR_SEG_IDLE: out = 0.0f; break;
  case ADSR_SEG_ATTACK:
- out = AdsrFilter();
-
- if(out > .99f)
+ x_ += D0 * (2.f - x_);
+ out = x_;
+ if(out > 1.f)
  {
+ x_ =
+ out = 1.f;
  mode_ = ADSR_SEG_DECAY;
- pole = Tau2Pole(seg_time_[ADSR_SEG_DECAY]);
- a_ = pole;
- b_ = 1.0f - pole;
  }
  break;
  case ADSR_SEG_DECAY:
  case ADSR_SEG_RELEASE:
- x_ *= sus_;
- out = AdsrFilter();
- if(out <= 0.01f)
+ x_ += D0 * (target - x_);
+ out = x_;
+ if(out < 0.0f)
+ {
+ x_ =
+ out = 0.f;
  mode_ = ADSR_SEG_IDLE;
+ }
  default: break;
  }
  return out;

Source/Control/adsr.h

@@ -31,31 +31,45 @@ enum
 Original author(s) : Paul Batchelor
 
 Ported from Soundpipe by Ben Sergentanis, May 2020
+
+Remake by Steffan DIedrichsen, May 2021
 */
 class Adsr
 {
  public:
- Adsr() {}
+ Adsr () {}
  ~Adsr() {}
  /** Initializes the Adsr module.
  \param sample_rate - The sample rate of the audio engine being run. 
  */
- void Init(float sample_rate);
+ void Init(float sample_rate, int blockSize = 1);
 
+ /**
+ \function Retrigger forces the envelope back to attack phase
+ \param hard resets the hosrory to zero, results in a click.
+ */
+
+ void Retrigger(bool hard);
 
+
  /** Processes one sample through the filter and returns one sample.
  \param gate - trigger the envelope, hold it to sustain 
  */
+
  float Process(bool gate);
 
  /** Sets time
  Set time per segment in seconds
  */
- inline void SetTime(int seg, float time) { seg_time_[seg] = time; }
+ void SetTime(int seg, float time);
  /** Sustain level
- \param sus_level - sets sustain level
+ \param sus_level - sets sustain level, 0...1.0
  */
- inline void SetSustainLevel(float sus_level) { sus_ = sus_level; }
+ inline void SetSustainLevel(float sus_level)
+ {
+ sus_level = (sus_level < 0.f)? 0.f : (sus_level > 1.f)? 1.f : sus_level;
+ sus_level_ = sus_level;
+ }
  /** get the current envelope segment
  \return the segment of the envelope that the phase is currently located in.
  */
@@ -66,11 +80,12 @@ class Adsr
  inline bool IsRunning() const { return mode_ != ADSR_SEG_IDLE; }
 
  private:
- float sus_, seg_time_[ADSR_SEG_LAST], a_, b_, y_, x_, prev_, atk_time_;
+ float sus_level_,
+ seg_time_[ADSR_SEG_LAST]{0.f},
+ seg_D0_[ADSR_SEG_LAST]{0.f},
+ x_;
  int sample_rate_;
  uint8_t mode_;
- float Tau2Pole(float tau);
- float AdsrFilter();
 };
 } // namespace daisysp
 #endif