From 6dd6d18009f29698ecbc88a699a5977b1fae5f1f Mon Sep 17 00:00:00 2001
From: abscisys <vincent_gauche@hotmail.com>
Date: Sat, 11 Feb 2023 00:12:55 +0100
Subject: [PATCH] FastLFO fixes

---
 src/fx_components.cpp                  | 39 ++++++++++++++++++--------
 src/fx_components.h                    |  2 ++
 src/test/cppcheck-suppression-list.txt |  2 ++
 src/test/test_cpp_performance.cpp      |  2 +-
 4 files changed, 32 insertions(+), 13 deletions(-)

diff --git a/src/fx_components.cpp b/src/fx_components.cpp
index 75d4b39..869c75b 100644
--- a/src/fx_components.cpp
+++ b/src/fx_components.cpp
@@ -29,6 +29,8 @@ FastLFO::FastLFO(float32_t sampling_rate, float32_t min_frequency, float32_t max
     max_frequency_(max_frequency),
     centered_(centered),
     frequency_(0.0f),
+    nb_sub_increment_(1),
+    sub_increment_(0),
     y0_(0.0f),
     y1_(0.0f),
     iir_coefficient_(0.0f),
@@ -54,6 +56,9 @@ void FastLFO::setNormalizedFrequency(float32_t normalized_frequency)
         this->frequency_ = frequency;
         this->unitary_frequency_ = this->frequency_ / this->getSamplingRate();
 
+        this->nb_sub_increment_ = (frequency >= 3.0f ? 1 : 300);
+        this->unitary_frequency_ *= this->nb_sub_increment_;
+
         this->updateCoefficient();
     }
 }
@@ -73,6 +78,9 @@ void FastLFO::setFrequency(float32_t frequency)
         this->frequency_ = frequency;
         this->unitary_frequency_ = this->frequency_ / this->getSamplingRate();
 
+        this->nb_sub_increment_ = (frequency >= 3.0f ? 1 : 300);
+        this->unitary_frequency_ *= this->nb_sub_increment_;
+
         this->updateCoefficient();
     }
 }
@@ -84,7 +92,7 @@ float32_t FastLFO::getFrequency() const
 
 void FastLFO::updateCoefficient()
 {
-    float32_t frequency = this->unitary_frequency_;
+    float32_t frequency = this->unitary_frequency_ * 268.0f / 240.0f;
 
     float32_t sign = 16.0f;
     frequency -= 0.25f;
@@ -112,6 +120,8 @@ void FastLFO::updateCoefficient()
 
 void FastLFO::reset()
 {
+    this->sub_increment_ = 0.0f;
+
     // computing cos(0) = sin(-PI/2)
     this->y1_ = this->initial_amplitude_;
     this->y0_ = 0.5f;
@@ -121,12 +131,12 @@ void FastLFO::reset()
         return;
     }
 
-    float32_t p_i = Constants::M2PI * this->unitary_frequency_;
-    float32_t p = 0.0f;
-    float32_t t_p = this->InitialPhase - Constants::MPI_2;
-    if(t_p < 0.0f)
+    float32_t p_i = Constants::M2PI * this->unitary_frequency_ / static_cast<float32_t>(this->nb_sub_increment_);
+    float32_t p = Constants::MPI_2;
+    float32_t t_p = this->InitialPhase;
+    if(t_p < p)
     {
-        t_p += Constants::M2PI;
+        p -= Constants::M2PI;
     }
     while(p < t_p)
     {
@@ -138,18 +148,23 @@ void FastLFO::reset()
 float32_t FastLFO::process()
 {
     float32_t temp = this->y0_;
-    this->y0_ = this->iir_coefficient_ * this->y0_ - this->y1_;
-    this->y1_ = temp;
+    float32_t current = temp + 0.5f;
     if(this->centered_)
     {
-        this->current_ = (temp + 0.5f) * 2.0f - 1.0f;
+        current = current * 2.0f - 1.0f;
     }
-    else
+
+    this->sub_increment_++;
+    if(this->sub_increment_ >= this->nb_sub_increment_)
     {
-        this->current_ = temp + 0.5f;
+        this->sub_increment_ = 0;
+        this->y0_ = this->iir_coefficient_ * this->y0_ - this->y1_;
+        this->y1_ = temp;
+        this->current_ = current;
+        return current;
     }
 
-    return this->current_;
+    return mapfloat(this->sub_increment_, 0, this->nb_sub_increment_, this->current_, current);
 }
 
 float32_t FastLFO::current() const
diff --git a/src/fx_components.h b/src/fx_components.h
index a660f48..0bb5acc 100644
--- a/src/fx_components.h
+++ b/src/fx_components.h
@@ -72,6 +72,8 @@ private:
     float32_t       frequency_;
     float32_t       normalized_frequency_;
     float32_t       unitary_frequency_;
+    size_t          nb_sub_increment_;
+    size_t          sub_increment_;
 
     float32_t       y0_;
     float32_t       y1_;
diff --git a/src/test/cppcheck-suppression-list.txt b/src/test/cppcheck-suppression-list.txt
index 0a2740b..6ad34ba 100644
--- a/src/test/cppcheck-suppression-list.txt
+++ b/src/test/cppcheck-suppression-list.txt
@@ -4,8 +4,10 @@ noExplicitConstructor:*
 unusedFunction:*
 missingIncludeSystem:*
 unmatchedSuppression:*
+unreadVariable:test*.cpp
 
 // unexplained exceptions
 syntaxError:beta.cpp:52
 syntaxError:test_fx_mixing_console.cpp:207
 internalAstError:test_cpp_performance.cpp:22
+unpreciseMathCall:*
diff --git a/src/test/test_cpp_performance.cpp b/src/test/test_cpp_performance.cpp
index 02a7f12..ce60681 100644
--- a/src/test/test_cpp_performance.cpp
+++ b/src/test/test_cpp_performance.cpp
@@ -67,7 +67,7 @@ TEST(CppPerformance, FastLFOTuning)
     full_test_name += test_info->name();
     
     size_t NB = static_cast<size_t>(1.0f * SAMPLING_FREQUENCY);
-    float32_t freq = 0.5f;
+    float32_t freq = 1.5f;
 
     FastLFO lfo1(SAMPLING_FREQUENCY, freq, 440.0f);
     lfo1.setFrequency(freq);