actually -- let's use the MySaw example from the help

Author: Nathan Ho

BoringMixer.cpp

@@ -1,5 +1,5 @@
 cmake_minimum_required (VERSION 2.8)
-set(PROJECT "BoringMixer")
+set(PROJECT "MySaw")
 project (${PROJECT})
 
 include_directories(${SC_PATH}/include/plugin_interface)
@@ -18,4 +18,4 @@ if (CMAKE_COMPILER_IS_GNUCXX OR CMAKE_COMPILER_IS_CLANG)
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")
 endif()
 
-add_library(${PROJECT} MODULE BoringMixer.cpp)
+add_library(${PROJECT} MODULE MySaw.cpp)

BoringMixer.sc

@@ -0,0 +1,140 @@
+#include "SC_PlugIn.h"
+
+// InterfaceTable contains pointers to functions in the host (server).
+static InterfaceTable *ft;
+
+// declare struct to hold unit generator state
+struct MySaw : public Unit
+{
+    double mPhase; // phase of the oscillator, from -1 to 1.
+    float mFreqMul; // a constant for multiplying frequency
+};
+
+// declare unit generator functions
+static void MySaw_next_a(MySaw *unit, int inNumSamples);
+static void MySaw_next_k(MySaw *unit, int inNumSamples);
+static void MySaw_Ctor(MySaw* unit);
+
+
+//////////////////////////////////////////////////////////////////
+
+// Ctor is called to initialize the unit generator.
+// It only executes once.
+
+// A Ctor usually does 3 things.
+// 1. set the calculation function.
+// 2. initialize the unit generator state variables.
+// 3. calculate one sample of output.
+void MySaw_Ctor(MySaw* unit)
+{
+    // 1. set the calculation function.
+    if (INRATE(0) == calc_FullRate) {
+        // if the frequency argument is audio rate
+        SETCALC(MySaw_next_a);
+    } else {
+        // if the frequency argument is control rate (or a scalar).
+        SETCALC(MySaw_next_k);
+    }
+
+    // 2. initialize the unit generator state variables.
+    // initialize a constant for multiplying the frequency
+    unit->mFreqMul = 2.0 * SAMPLEDUR;
+    // get initial phase of oscillator
+    unit->mPhase = IN0(1);
+
+    // 3. calculate one sample of output.
+    MySaw_next_k(unit, 1);
+}
+
+
+//////////////////////////////////////////////////////////////////
+
+// The calculation function executes once per control period
+// which is typically 64 samples.
+
+// calculation function for an audio rate frequency argument
+void MySaw_next_a(MySaw *unit, int inNumSamples)
+{
+    // get the pointer to the output buffer
+    float *out = OUT(0);
+
+    // get the pointer to the input buffer
+    float *freq = IN(0);
+
+    // get phase and freqmul constant from struct and store it in a
+    // local variable.
+    // The optimizer will cause them to be loaded it into a register.
+    float freqmul = unit->mFreqMul;
+    double phase = unit->mPhase;
+
+    // perform a loop for the number of samples in the control period.
+    // If this unit is audio rate then inNumSamples will be 64 or whatever
+    // the block size is. If this unit is control rate then inNumSamples will
+    // be 1.
+    for (int i=0; i < inNumSamples; ++i)
+    {
+        // out must be written last for in place operation
+        float z = phase;
+        phase += freq[i] * freqmul;
+
+        // these if statements wrap the phase a +1 or -1.
+        if (phase >= 1.f) phase -= 2.f;
+        else if (phase <= -1.f) phase += 2.f;
+
+        // write the output
+        out[i] = z;
+    }
+
+    // store the phase back to the struct
+    unit->mPhase = phase;
+}
+
+//////////////////////////////////////////////////////////////////
+
+// calculation function for a control rate frequency argument
+void MySaw_next_k(MySaw *unit, int inNumSamples)
+{
+    // get the pointer to the output buffer
+    float *out = OUT(0);
+
+    // freq is control rate, so calculate it once.
+    float freq = IN0(0) * unit->mFreqMul;
+
+    // get phase from struct and store it in a local variable.
+    // The optimizer will cause it to be loaded it into a register.
+    double phase = unit->mPhase;
+
+    // since the frequency is not changing then we can simplify the loops
+    // by separating the cases of positive or negative frequencies.
+    // This will make them run faster because there is less code inside the loop.
+    if (freq >= 0.f) {
+        // positive frequencies
+        for (int i=0; i < inNumSamples; ++i)
+        {
+            out[i] = phase;
+            phase += freq;
+            if (phase >= 1.f) phase -= 2.f;
+        }
+    } else {
+        // negative frequencies
+        for (int i=0; i < inNumSamples; ++i)
+        {
+            out[i] = phase;
+            phase += freq;
+            if (phase <= -1.f) phase += 2.f;
+        }
+    }
+
+    // store the phase back to the struct
+    unit->mPhase = phase;
+}
+
+
+// the entry point is called by the host when the plug-in is loaded
+PluginLoad(MySaw)
+{
+    // InterfaceTable *inTable implicitly given as argument to the load function
+    ft = inTable; // store pointer to InterfaceTable
+
+    DefineSimpleUnit(MySaw);
+}

CMakeLists.txt

@@ -0,0 +1,9 @@
+// without mul and add.
+MySaw : UGen {
+    *ar { arg freq = 440.0, iphase = 0.0;
+        ^this.multiNew('audio', freq, iphase)
+    }
+    *kr { arg freq = 440.0, iphase = 0.0;
+        ^this.multiNew('control', freq, iphase)
+    }
+}

MySaw.cpp

@@ -1,4 +1,4 @@
-This is a minimal example of a SuperCollider server plugin. It compiles a "BoringMixer" ugen that takes the average of its two audio-rate inputs.
+This is a minimal example of a SuperCollider server plugin. It compiles a "MySaw" ugen, which is a simple saw oscillator with controllable frequency and initial phase.
 
 ## Compiling