#1: Fixes for incompatibility on OSX

cpp/Makefile

@@ -0,0 +1,12 @@
+.PHONY: clean bundle
+
+CC=g++
+generator: main.cpp
+	$(CC) -o generator `sdl-config --cflags --libs` main.cpp
+
+bundle: generator
+	sh makeAppBundle
+
+clean: 
+	$(RM) generator
+

cpp/main.cpp

@@ -0,0 +1,128 @@
+#include <SDL/SDL.h>
+#include <SDL/SDL_audio.h>
+#include <queue>
+#include <cmath>
+
+const int AMPLITUDE = 28000;
+const int FREQUENCY = 44100;
+
+struct BeepObject
+{
+    double freq;
+    int samplesLeft;
+};
+
+class Beeper
+{
+private:
+    double v;
+    std::queue<BeepObject> beeps;
+public:
+    Beeper();
+    ~Beeper();
+    void beep(double freq, int duration);
+    void generateSamples(Sint16 *stream, int length);
+    void wait();
+};
+
+void audio_callback(void*, Uint8*, int);
+
+Beeper::Beeper()
+{
+    SDL_AudioSpec desiredSpec;
+
+    desiredSpec.freq = FREQUENCY;
+    desiredSpec.format = AUDIO_S16SYS;
+    desiredSpec.channels = 1;
+    desiredSpec.samples = 2048;
+    desiredSpec.callback = audio_callback;
+    desiredSpec.userdata = this;
+
+    SDL_AudioSpec obtainedSpec;
+
+    // you might want to look for errors here
+    SDL_OpenAudio(&desiredSpec, &obtainedSpec);
+
+    // start play audio
+    SDL_PauseAudio(0);
+}
+
+Beeper::~Beeper()
+{
+    SDL_CloseAudio();
+}
+
+void Beeper::generateSamples(Sint16 *stream, int length)
+{
+    int i = 0;
+    while (i < length) {
+
+        if (beeps.empty()) {
+            while (i < length) {
+                stream[i] = 0;
+                i++;
+            }
+            return;
+        }
+        BeepObject& bo = beeps.front();
+
+        int samplesToDo = std::min(i + bo.samplesLeft, length);
+        bo.samplesLeft -= samplesToDo - i;
+
+        while (i < samplesToDo) {
+            stream[i] = AMPLITUDE * std::sin(v * 2 * M_PI / FREQUENCY);
+            i++;
+            v += bo.freq;
+        }
+
+        if (bo.samplesLeft == 0) {
+            beeps.pop();
+        }
+    }
+}
+
+void Beeper::beep(double freq, int duration)
+{
+    BeepObject bo;
+    bo.freq = freq;
+    bo.samplesLeft = duration * FREQUENCY / 1000;
+
+    SDL_LockAudio();
+    beeps.push(bo);
+    SDL_UnlockAudio();
+}
+
+void Beeper::wait()
+{
+    int size;
+    do {
+        SDL_Delay(20);
+        SDL_LockAudio();
+        size = beeps.size();
+        SDL_UnlockAudio();
+    } while (size > 0);
+
+}
+
+void audio_callback(void *_beeper, Uint8 *_stream, int _length)
+{
+    Sint16 *stream = (Sint16*) _stream;
+    int length = _length / 2;
+    Beeper* beeper = (Beeper*) _beeper;
+
+    beeper->generateSamples(stream, length);
+}
+
+int main(int argc, char* argv[])
+{
+    SDL_Init(SDL_INIT_AUDIO);
+
+    int duration = 1000;
+    double Hz = 440;
+
+    Beeper b;
+    b.beep(Hz, duration);
+    b.wait();
+
+    return 0;
+}

generator.c

@@ -31,6 +31,7 @@ void usage() {
 }
 
 int main(int argc, char* argv[]) {
+  errno = 0;
 	/* This will hold our data */
 	SDL_AudioSpec spec;
 	/* This will hold the requested frequency */