From 1983894bc8c4fdb085775c9510fd7f2278592596 Mon Sep 17 00:00:00 2001
From: Jean Pierre Cimalando <jp-dev@inbox.ru>
Date: Sun, 15 Nov 2020 12:04:01 +0100
Subject: [PATCH] Add the phase generator by beat clock

---
 src/sfizz/BeatClock.cpp | 34 ++++++++++++++++++++++++++++++++++
 src/sfizz/BeatClock.h   | 10 ++++++++++
 2 files changed, 44 insertions(+)

diff --git a/src/sfizz/BeatClock.cpp b/src/sfizz/BeatClock.cpp
index 32e997c7..acc5e382 100644
--- a/src/sfizz/BeatClock.cpp
+++ b/src/sfizz/BeatClock.cpp
@@ -199,6 +199,40 @@ void BeatClock::fillBufferUpTo(unsigned delay)
     mustApplyHostPos_ = mustApplyHostPos;
 }
 
+void BeatClock::calculatePhase(float beatPeriod, float* phaseOut)
+{
+    const unsigned numFrames = currentCycleFrames_;
+
+    if (beatPeriod == 0.0f) {
+        fill(absl::MakeSpan(phaseOut, numFrames), 0.0f);
+        return;
+    }
+
+    const float invBeatPeriod = 1.0f / beatPeriod;
+    const float* beatPositionData = getRunningBeatPosition().data();
+
+    for (unsigned i = 0; i < numFrames; ++i) {
+        float beatPosition = std::max(0.0f, beatPositionData[i]);
+        float phase = beatPosition * invBeatPeriod;
+        phase -= static_cast<int>(phase);
+        phaseOut[i] = phase;
+    }
+}
+
+void BeatClock::calculatePhaseModulated(const float* beatPeriodData, float* phaseOut)
+{
+    const unsigned numFrames = currentCycleFrames_;
+    const float* beatPositionData = getRunningBeatPosition().data();
+
+    for (unsigned i = 0; i < numFrames; ++i) {
+        float beatPeriod = beatPeriodData[i];
+        float beatPosition = std::max(0.0f, beatPositionData[i]);
+        float phase = beatPosition / beatPeriod;
+        phase -= static_cast<int>(phase);
+        phaseOut[i] = (beatPeriod != 0.0f) ? phase : 0.0f;
+    }
+}
+
 } // namespace sfz
 
 std::ostream& operator<<(std::ostream& os, const sfz::BBT& pos)
diff --git a/src/sfizz/BeatClock.h b/src/sfizz/BeatClock.h
index b75ba182..cccc76e8 100644
--- a/src/sfizz/BeatClock.h
+++ b/src/sfizz/BeatClock.h
@@ -130,6 +130,16 @@ public:
      * @brief Get the time signature numerator for each frame of the current cycle.
      */
     absl::Span<const int> getRunningBeatsPerBar();
+    /**
+     * @brief Create a normalized phase signal for LFO which completes a
+     *        period every N-th beat.
+     */
+    void calculatePhase(float beatPeriod, float* phaseOut);
+    /**
+     * @brief Create a normalized phase signal for LFO which completes a
+     *        period every N-th beat, where N can vary over time.
+     */
+    void calculatePhaseModulated(const float* beatPeriodData, float* phaseOut);
 
 private:
     void fillBufferUpTo(unsigned delay);