Merge pull request electro-smith#49 from beserge/samplehold

Added sample and hold module

daisysp.h

@@ -49,6 +49,7 @@
 #include "modules/PolyPluck.h"
 #include "modules/pluck.h"
 #include "modules/reverbsc.h"
+#include "modules/samplehold.h"
 #include "modules/svf.h"
 #include "modules/tone.h"
 #include "modules/whitenoise.h"

examples/samplehold/Makefile

@@ -0,0 +1,14 @@
+# Project Name
+TARGET = ex_samplehold
+
+# Sources
+CPP_SOURCES = ex_samplehold.cpp
+
+# Library Locations
+LIBDAISY_DIR ?= ../../../libdaisy
+DAISYSP_DIR ?= ../../../DaisySP
+
+# Core location, and generic Makefile.
+SYSTEM_FILES_DIR = $(LIBDAISY_DIR)/core
+include $(SYSTEM_FILES_DIR)/Makefile
+

examples/samplehold/ex_samplehold.cpp

@@ -0,0 +1,77 @@
+#include "daisysp.h"
+#include "daisy_seed.h"
+
+// Interleaved audio definitions
+#define LEFT (i)
+#define RIGHT (i + 1)
+
+using namespace daisysp;
+using namespace daisy;
+
+static DaisySeed  seed;
+static Oscillator osc;
+static Metro      tick;
+static WhiteNoise noise;
+static AdEnv      env;
+static SampleHold sh;
+
+float osc_out = 0;
+
+static void AudioCallback(float *in, float *out, size_t size)
+{
+    float osc_out, env_out;
+    for(size_t i = 0; i < size; i += 2)
+    {
+        uint8_t trig      = tick.Process();
+        float   newsample = sh.Process(
+            trig, noise.Process() * 500 + 500, sh.MODE_SAMPLE_HOLD);
+
+        // When the metro ticks, trigger the envelope to start.
+        if(trig)
+        {
+            env.Trigger();
+            tick.SetFreq(newsample / 100 + 1);
+            osc.SetFreq(newsample);
+        }
+
+        // Use envelope to control the amplitude of the oscillator.
+        env_out = env.Process();
+        osc.SetAmp(env_out);
+        osc_out = osc.Process();
+
+        out[LEFT]  = osc_out;
+        out[RIGHT] = osc_out;
+    }
+}
+
+int main(void)
+{
+    // initialize seed hardware and daisysp modules
+    float sample_rate;
+    seed.Configure();
+    seed.Init();
+    sample_rate = seed.AudioSampleRate();
+    env.Init(sample_rate);
+    osc.Init(sample_rate);
+    tick.Init(1, sample_rate);
+
+    // set adenv parameters
+    env.SetTime(ADENV_SEG_ATTACK, 0.01);
+    env.SetTime(ADENV_SEG_DECAY, 0.1);
+    env.SetMin(0.0);
+    env.SetMax(0.25);
+    env.SetCurve(0.5);
+
+    // Set parameters for oscillator
+    osc.SetWaveform(osc.WAVE_TRI);
+    osc.SetFreq(220);
+    osc.SetAmp(0.25);
+
+    noise.Init();
+
+    // start callback
+    seed.StartAudio(AudioCallback);
+
+
+    while(1) {}
+}

modules/samplehold.h

@@ -0,0 +1,61 @@
+#pragma once
+#ifndef DSY_SAMPLEHOLD_H
+#define DSY_SAMPLEHOLD_H
+
+#include <stdint.h>
+#ifdef __cplusplus
+
+namespace daisysp
+{
+/** Dual track and hold / Sample and hold module. \n 
+    Ported from soundpipe by Ben Sergentanis, June 2020.
+    @author Paul Batchelor
+    @date   2015
+*/
+class SampleHold
+{
+  public:
+    SampleHold() {}
+    ~SampleHold() {}
+
+    enum Mode
+    {
+        MODE_SAMPLE_HOLD,
+        MODE_TRACK_HOLD,
+        MODE_LAST,
+    };
+
+    /** Process the next sample. Both sample and track and hold are run in parallel
+    \param trigger Trigger the sample/track and hold
+    \param input   Signal to be sampled/tracked and held
+    \param mode    Whether to output the tracked or sampled values.
+    */
+    inline float
+    Process(bool trigger, float input, Mode mode = MODE_SAMPLE_HOLD)
+    {
+        Update(trigger, input);
+        return mode == MODE_SAMPLE_HOLD ? sample_ : track_;
+    }
+
+  private:
+    float track_    = 0;
+    float sample_   = 0;
+    bool  previous_ = false;
+
+
+    inline void Update(bool trigger, float input)
+    {
+        if(trigger)
+        {
+            if(!previous_)
+            {
+                sample_ = input;
+            }
+            track_ = input;
+        }
+        previous_ = trigger;
+    }
+};
+} // namespace daisysp
+#endif
+#endif