automata/README

## README
to get it working, install Emscripten:

https://github.com/kripken/emscripten/wiki/Tutorial

(on Ubuntu: https://github.com/kripken/emscripten/wiki/Getting-Started-on-Ubuntu-12.10)

set all the env variables and run build.sh.

open sin_audiodata.html in your Firefox.

## build.sh
#!/bin/bash

emcc sin.cpp -o sin.js \
  -s EXPORTED_FUNCTIONS="['_Sin_constructor','_Sin_destructor','_Sin_setFrequency','_Sin_setAmplitude','_Sin_getFrequency','_Sin_computeBuffer']"

cat sin-proxy.js >> sin.js

## sin-proxy.js
// get references to the exposed proxy functions
var Sin_constructor = Module.cwrap('Sin_constructor', 'number', ['number', 'number']);
var Sin_destructor = Module.cwrap('Sin_destructor', null, ['number']);
var Sin_setFrequency = Module.cwrap('Sin_setFrequency', null, ['number', 'number']);
var Sin_setAmplitude = Module.cwrap('Sin_setAmplitude', null, ['number', 'number']);
var Sin_getFrequency = Module.cwrap('Sin_getFrequency', 'number', ['number']);
var Sin_computeBuffer = Module.cwrap('Sin_computeBuffer', null, ['number', 'number', 'number', 'number']);

Sin = function (freq, amp) {
  that = {};

  that.ptr = Sin_constructor(freq, amp);

  that.destroy = function () {
    Sin_destructor(that.ptr);
  };

  that.setFrequency = function (x) {
    Sin_setFrequency(that.ptr, x);
  };

  that.setAmplitude = function (x) {
    Sin_setAmplitude(that.ptr, x);
  };

  that.getFrequency = function () {
    return Sin_getFrequency(that.ptr);
  };

  that.computeBuffer = function (buffer, size, samplePos) {
    Sin_computeBuffer(that.ptr, buffer, size, samplePos);
  };

  return that;
};

## sin.cpp
#include <new>
#include <cmath>
#include <cstdlib>

static const float PI = 3.14159265358979f;

using namespace std;

class Sin {

public:
  float amplitude, frequency, sampleRate;

  Sin (float frequencyV, float amplitudeV) {
    this->frequency = frequencyV;
    this->amplitude = amplitudeV;
    this->sampleRate = 44100;
  }

  ~Sin() {
  }

  void setFrequency(float v) {
    this->frequency = v;
  }

  void setAmplitude(float v) {
    this->amplitude = v;
  }

  float getFrequency() {
    return this->frequency;
  }

  void computeBuffer(float *buffer, int size, int samplePos) {
    int i;
    float k = 2 * PI * this->frequency / this->sampleRate;
    for (i=0; i<size; i++) {
      buffer[i] = sin(k * samplePos++);
    }
  }
};

//compile using "C" linkage to avoid name obfuscation
extern "C" {
  //constructor, returns a pointer to the HelloWorld object
  void *Sin_constructor(float freq, float amp) {
    Sin* obj = new Sin(freq, amp);
    return obj;
  }

  void Sin_setFrequency(Sin *s, float freq) {
    s->setFrequency(freq);
  }

  void Sin_setAmplitude(Sin *s, float amp) {
    s->setAmplitude(amp);
  }

  float Sin_getFrequency(Sin *s) {
    return s->getFrequency();
  }

  void Sin_computeBuffer(Sin *s, float *buffer, int size, int samplePos) {
    s->computeBuffer(buffer, size, samplePos);
  }

  void Sin_destructor(Sin *s) {
    delete s;
  }

};

// main() {
//   float *buf;
//   Sin s (220.0, 1.5);
//   s.setFrequency(440.0);
//   s.computeBuffer();
//   buf = s.buffer;

//   cout << buf[1] << endl;
//   return 0;
// }

## sin_audiodata.html
<!DOCTYPE html>
<html>
  <head>
    <title> sin </title>

    <script src="sin.js"></script>

  </head>
  <body>
    <input type="text" size="4" id="freq" value="220"><label for="hz">Hz</label>
    <button onclick="start()">play</button>
    <button onclick="stop()">stop</button>

    <script type="text/javascript">
      function AudioDataDestination(sampleRate, readFn) {
        var audio = new Audio();
        audio.mozSetup(1, sampleRate);

        var currentWritePosition = 0;
        var prebufferSize = sampleRate / 2; // buffer 500ms
        var tail = null, tailPosition;

        setInterval(function() {
          var written;
          // Check if some data was not written in previous attempts.
          if(tail) {
            written = audio.mozWriteAudio(tail.subarray(tailPosition));
            currentWritePosition += written;
            tailPosition += written;
            if(tailPosition < tail.length) {
              // Not all the data was written, saving the tail...
              return; // ... and exit the function.
            }
            tail = null;
          }

          // Check if we need add some data to the audio output.
          var currentPosition = audio.mozCurrentSampleOffset();
          var available = currentPosition + prebufferSize - currentWritePosition;
          if(available > 0) {
            // Request some sound data from the callback function.
            var soundData = new Float32Array(available);
            readFn(soundData);

            // Writting the data.
            written = audio.mozWriteAudio(soundData);
            if(written < soundData.length) {
              // Not all the data was written, saving the tail.
              tail = soundData;
              tailPosition = written;
            }
            currentWritePosition += written;
          }
        }, 100);
      }

      // Control and generate the sound.

      var frequency = 0, currentSoundSample;
      var sampleRate = 44100;

      function requestSoundData(soundData) {
        if (!frequency) {
          return; // no sound selected
        }

  // get the length of the data in bytes
  var bufferBytes = soundData.length * soundData.BYTES_PER_ELEMENT;

  // malloc enough space for the data
  var bufferPtr = _malloc(bufferBytes);

  // get a bytes-wise view on the newly allocated buffer
  var heapBytes= new Uint8Array(Module.HEAPU8.buffer, bufferPtr, bufferBytes);

  // copy data into heapBytes
  heapBytes.set(new Uint8Array(soundData.buffer));

  // call the c function which should modify the vals
  s = Sin(frequency, 1.0);
  s.computeBuffer(heapBytes.byteOffset, soundData.length, currentSoundSample);

  // print out the results of the c function
  var heapFloats= new Float32Array(heapBytes.buffer, heapBytes.byteOffset,
  soundData.length);

  for (var i=0, size=soundData.length; i<size; i++) {
    soundData[i] = heapFloats[i];
  }

  currentSoundSample += soundData.length;

  _free(heapBytes.byteOffset);

}

      var audioDestination = new AudioDataDestination(sampleRate, requestSoundData);

      function start() {
        currentSoundSample = 0;
        frequency = parseFloat(document.getElementById("freq").value);
      }

      function stop() {
        frequency = 0;
      }
  </script>
  </body>
</html>
	to get it working, install Emscripten:

	https://github.com/kripken/emscripten/wiki/Tutorial

	(on Ubuntu: https://github.com/kripken/emscripten/wiki/Getting-Started-on-Ubuntu-12.10)

	set all the env variables and run build.sh.

	open sin_audiodata.html in your Firefox.
	#!/bin/bash

	emcc sin.cpp -o sin.js \
	-s EXPORTED_FUNCTIONS="['_Sin_constructor','_Sin_destructor','_Sin_setFrequency','_Sin_setAmplitude','_Sin_getFrequency','_Sin_computeBuffer']"

	cat sin-proxy.js >> sin.js
	// get references to the exposed proxy functions
	var Sin_constructor = Module.cwrap('Sin_constructor', 'number', ['number', 'number']);
	var Sin_destructor = Module.cwrap('Sin_destructor', null, ['number']);
	var Sin_setFrequency = Module.cwrap('Sin_setFrequency', null, ['number', 'number']);
	var Sin_setAmplitude = Module.cwrap('Sin_setAmplitude', null, ['number', 'number']);
	var Sin_getFrequency = Module.cwrap('Sin_getFrequency', 'number', ['number']);
	var Sin_computeBuffer = Module.cwrap('Sin_computeBuffer', null, ['number', 'number', 'number', 'number']);

	Sin = function (freq, amp) {
	that = {};

	that.ptr = Sin_constructor(freq, amp);

	that.destroy = function () {
	Sin_destructor(that.ptr);
	};

	that.setFrequency = function (x) {
	Sin_setFrequency(that.ptr, x);
	};

	that.setAmplitude = function (x) {
	Sin_setAmplitude(that.ptr, x);
	};

	that.getFrequency = function () {
	return Sin_getFrequency(that.ptr);
	};

	that.computeBuffer = function (buffer, size, samplePos) {
	Sin_computeBuffer(that.ptr, buffer, size, samplePos);
	};

	return that;
	};
	#include <new>
	#include <cmath>
	#include <cstdlib>

	static const float PI = 3.14159265358979f;

	using namespace std;

	class Sin {

	public:
	float amplitude, frequency, sampleRate;

	Sin (float frequencyV, float amplitudeV) {
	this->frequency = frequencyV;
	this->amplitude = amplitudeV;
	this->sampleRate = 44100;
	}

	~Sin() {
	}

	void setFrequency(float v) {
	this->frequency = v;
	}

	void setAmplitude(float v) {
	this->amplitude = v;
	}

	float getFrequency() {
	return this->frequency;
	}

	void computeBuffer(float *buffer, int size, int samplePos) {
	int i;
	float k = 2 * PI * this->frequency / this->sampleRate;
	for (i=0; i<size; i++) {
	buffer[i] = sin(k * samplePos++);
	}
	}
	};

	//compile using "C" linkage to avoid name obfuscation
	extern "C" {
	//constructor, returns a pointer to the HelloWorld object
	void *Sin_constructor(float freq, float amp) {
	Sin* obj = new Sin(freq, amp);
	return obj;
	}

	void Sin_setFrequency(Sin *s, float freq) {
	s->setFrequency(freq);
	}

	void Sin_setAmplitude(Sin *s, float amp) {
	s->setAmplitude(amp);
	}

	float Sin_getFrequency(Sin *s) {
	return s->getFrequency();
	}

	void Sin_computeBuffer(Sin s, float buffer, int size, int samplePos) {
	s->computeBuffer(buffer, size, samplePos);
	}

	void Sin_destructor(Sin *s) {
	delete s;
	}

	};

	// main() {
	// float *buf;
	// Sin s (220.0, 1.5);
	// s.setFrequency(440.0);
	// s.computeBuffer();
	// buf = s.buffer;

	// cout << buf[1] << endl;
	// return 0;
	// }
	<!DOCTYPE html>
	<html>
	<head>
	<title> sin </title>

	<script src="sin.js"></script>

	</head>
	<body>
	<input type="text" size="4" id="freq" value="220"><label for="hz">Hz</label>
	<button onclick="start()">play</button>
	<button onclick="stop()">stop</button>

	<script type="text/javascript">
	function AudioDataDestination(sampleRate, readFn) {
	var audio = new Audio();
	audio.mozSetup(1, sampleRate);

	var currentWritePosition = 0;
	var prebufferSize = sampleRate / 2; // buffer 500ms
	var tail = null, tailPosition;

	setInterval(function() {
	var written;
	// Check if some data was not written in previous attempts.
	if(tail) {
	written = audio.mozWriteAudio(tail.subarray(tailPosition));
	currentWritePosition += written;
	tailPosition += written;
	if(tailPosition < tail.length) {
	// Not all the data was written, saving the tail...
	return; // ... and exit the function.
	}
	tail = null;
	}

	// Check if we need add some data to the audio output.
	var currentPosition = audio.mozCurrentSampleOffset();
	var available = currentPosition + prebufferSize - currentWritePosition;
	if(available > 0) {
	// Request some sound data from the callback function.
	var soundData = new Float32Array(available);
	readFn(soundData);

	// Writting the data.
	written = audio.mozWriteAudio(soundData);
	if(written < soundData.length) {
	// Not all the data was written, saving the tail.
	tail = soundData;
	tailPosition = written;
	}
	currentWritePosition += written;
	}
	}, 100);
	}

	// Control and generate the sound.

	var frequency = 0, currentSoundSample;
	var sampleRate = 44100;

	function requestSoundData(soundData) {
	if (!frequency) {
	return; // no sound selected
	}

	// get the length of the data in bytes
	var bufferBytes = soundData.length * soundData.BYTES_PER_ELEMENT;

	// malloc enough space for the data
	var bufferPtr = _malloc(bufferBytes);

	// get a bytes-wise view on the newly allocated buffer
	var heapBytes= new Uint8Array(Module.HEAPU8.buffer, bufferPtr, bufferBytes);

	// copy data into heapBytes
	heapBytes.set(new Uint8Array(soundData.buffer));

	// call the c function which should modify the vals
	s = Sin(frequency, 1.0);
	s.computeBuffer(heapBytes.byteOffset, soundData.length, currentSoundSample);

	// print out the results of the c function
	var heapFloats= new Float32Array(heapBytes.buffer, heapBytes.byteOffset,
	soundData.length);

	for (var i=0, size=soundData.length; i<size; i++) {
	soundData[i] = heapFloats[i];
	}

	currentSoundSample += soundData.length;

	_free(heapBytes.byteOffset);

	}

	var audioDestination = new AudioDataDestination(sampleRate, requestSoundData);

	function start() {
	currentSoundSample = 0;
	frequency = parseFloat(document.getElementById("freq").value);
	}

	function stop() {
	frequency = 0;
	}
	</script>
	</body>
	</html>