portemento, adsr

Source/adsr.cpp

@@ -0,0 +1,148 @@
+/*
+  ==============================================================================
+
+    adsr.cpp
+    Created: 25 Oct 2025 2:09:32pm
+    Author:  mickl
+
+  ==============================================================================
+*/
+
+#include "adsr.h"
+#include "math.h"
+
+#ifndef M_E
+#define M_E 2.71828182845904523536
+#endif
+
+
+void Adsr::Init(float sample_rate, int blockSize)
+{
+    sample_rate_ = sample_rate / blockSize;
+    attackShape_ = -1.f;
+    attackTarget_ = 0.0f;
+    attackTime_ = -1.f;
+    decayTime_ = -1.f;
+    releaseTime_ = -1.f;
+    sus_level_ = 0.7f;
+    x_ = 0.0f;
+    gate_ = false;
+    mode_ = ADSR_SEG_IDLE;
+
+    SetTime(ADSR_SEG_ATTACK, 0.1f);
+    SetTime(ADSR_SEG_DECAY, 0.1f);
+    SetTime(ADSR_SEG_RELEASE, 0.1f);
+}
+
+void Adsr::Retrigger(bool hard)
+{
+    mode_ = ADSR_SEG_ATTACK;
+    if (hard)
+        x_ = 0.f;
+}
+
+void Adsr::SetTime(int seg, float time)
+{
+    switch (seg)
+    {
+    case ADSR_SEG_ATTACK: SetAttackTime(time, 0.0f); break;
+    case ADSR_SEG_DECAY:
+    {
+        SetTimeConstant(time, decayTime_, decayD0_);
+    }
+    break;
+    case ADSR_SEG_RELEASE:
+    {
+        SetTimeConstant(time, releaseTime_, releaseD0_);
+    }
+    break;
+    default: return;
+    }
+}
+
+void Adsr::SetAttackTime(float timeInS, float shape)
+{
+    if ((timeInS != attackTime_) || (shape != attackShape_))
+    {
+        attackTime_ = timeInS;
+        attackShape_ = shape;
+        if (timeInS > 0.f)
+        {
+            float x = shape;
+            float target = 9.f * powf(x, 10.f) + 0.3f * x + 1.01f;
+            attackTarget_ = target;
+            float logTarget = logf(1.f - (1.f / target)); // -1 for decay
+            attackD0_ = 1.f - expf(logTarget / (timeInS * sample_rate_));
+        }
+        else
+            attackD0_ = 1.f; // instant change
+    }
+}
+void Adsr::SetDecayTime(float timeInS)
+{
+    SetTimeConstant(timeInS, decayTime_, decayD0_);
+}
+void Adsr::SetReleaseTime(float timeInS)
+{
+    SetTimeConstant(timeInS, releaseTime_, releaseD0_);
+}
+
+
+void Adsr::SetTimeConstant(float timeInS, float& time, float& coeff)
+{
+    if (timeInS != time)
+    {
+        time = timeInS;
+        if (time > 0.f)
+        {
+            const float target = logf(1. / M_E);
+            coeff = 1.f - expf(target / (time * sample_rate_));
+        }
+        else
+            coeff = 1.f; // instant change
+    }
+}
+
+
+float Adsr::Process(bool gate)
+{
+    float out = 0.0f;
+
+    if (gate && !gate_) // rising edge
+        mode_ = ADSR_SEG_ATTACK;
+    else if (!gate && gate_) // falling edge
+        mode_ = ADSR_SEG_RELEASE;
+    gate_ = gate;
+
+    float D0(attackD0_);
+    if (mode_ == ADSR_SEG_DECAY)
+        D0 = decayD0_;
+    else if (mode_ == ADSR_SEG_RELEASE)
+        D0 = releaseD0_;
+
+    float target = mode_ == ADSR_SEG_DECAY ? sus_level_ : -0.01f;
+    switch (mode_)
+    {
+    case ADSR_SEG_IDLE: out = 0.0f; break;
+    case ADSR_SEG_ATTACK:
+        x_ += D0 * (attackTarget_ - x_);
+        out = x_;
+        if (out > 1.f)
+        {
+            x_ = out = 1.f;
+            mode_ = ADSR_SEG_DECAY;
+        }
+        break;
+    case ADSR_SEG_DECAY:
+    case ADSR_SEG_RELEASE:
+        x_ += D0 * (target - x_);
+        out = x_;
+        if (out < 0.0f)
+        {
+            x_ = out = 0.f;
+            mode_ = ADSR_SEG_IDLE;
+        }
+    default: break;
+    }
+    return out;
+}