nodesynth/notes.js

Library for audio synthesis

// Generated by CoffeeScript 1.10.0
(function() {
  var Common, Note, chromaticInterval, chromaticNotes, i, interval, intervalMap, j, k, l, len, len1, len2, m, n, name, names,
    bind = function(fn, me){ return function(){ return fn.apply(me, arguments); }; },
    extend = function(child, parent) { for (var key in parent) { if (hasProp.call(parent, key)) child[key] = parent[key]; } function ctor() { this.constructor = child; } ctor.prototype = parent.prototype; child.prototype = new ctor(); child.__super__ = parent.prototype; return child; },
    hasProp = {}.hasOwnProperty;

  chromaticInterval = Math.pow(2, 1.0 / 12.0);

  chromaticNotes = ['C', 'C#', 'D', 'D#', 'E', 'F', 'F#', 'G', 'G#', 'A', 'A#', 'B'];

  intervalMap = [['perfect_unison', 'unison', 'P1', 'diminished_second', 'd2'], ['minor_second', 'm2', 'augmented_unison', 'A1', 'semitone', 'S'], ['major_second', 'M2', 'diminished_third', 'd3', 'tone', 'whole_tone', 'T'], ['minor_third', 'm3', 'augmented_second', 'A2'], ['major_third', 'M3', 'diminished_fourth', 'd4'], ['perfect_fourth', 'fourth', 'P4', 'augmented_third', 'A3'], ['tritone', 'diminished_fifth', 'd5', 'augmented_fourth', 'A4', 'TT'], ['perfect_fifth', 'fifth', 'P5', 'diminished_sixth', 'd6'], ['minor_sixth', 'm6', 'augmented_fifth', 'A5'], ['major_sixth', 'M6', 'diminished_seventh', 'd7'], ['minor_seventh', 'm7', 'augmented_sixth', 'A6'], ['major_seventh', 'M7', 'diminished_octave', 'd8'], ['perfect_octave', 'octave', 'P8', 'augmented_seventh', 'A7']];

  Common = require('./common');

  Note = (function(superClass) {
    extend(Note, superClass);

    function Note(note, octave) {
      this.valueAt = bind(this.valueAt, this);
      var rn, ro, steps;
      this.note = note.toUpperCase();
      this.octave = octave;
      if (chromaticNotes.indexOf(this.note) === -1) {
        raise("Invalid note value: " + note);
      }
      if (octave < 0) {
        raise("Invalid octave: " + octave + ", must be >= 0");
      }
      rn = -(chromaticNotes.indexOf('A') - chromaticNotes.indexOf(this.note));
      ro = this.octave - 4;
      steps = (ro * 12) + rn;
      this.freq = 440 * (Math.pow(chromaticInterval, steps));
    }

    Note.prototype.valueOf = function() {
      return this.freq;
    };

    Note.prototype.valueAt = function(t) {
      return this.freq;
    };

    Note.prototype.transpose = function(semitones) {
      var ni, oct;
      oct = this.octave;
      ni = chromaticNotes.indexOf(this.note);
      ni += semitones;
      while (ni >= chromaticNotes.length) {
        oct += 1;
        ni -= chromaticNotes.length;
      }
      while (ni < 0) {
        oct -= 1;
        ni += chromaticNotes.length;
      }
      return this.constructor.retrieve(chromaticNotes[ni], oct);
    };

    Note.prototype.next = function() {
      return this.transpose(1);
    };

    Note.prototype.previous = function() {
      return this.transpose(-1);
    };

    Note.prototype.nextOctave = function() {
      return this.transpose(12);
    };

    Note.prototype.previousOctave = function() {
      return this.transpose(-12);
    };

    Note.prototype.toString = function() {
      return "" + this.note + this.octave;
    };

    Note.retrieve = function(note, octave) {
      var name;
      note = note.toUpperCase();
      name = note.replace('#', 'Sharp') + octave;
      if (global[name] == null) {
        global[name] = new Note(note, octave);
      }
      return global[name];
    };

    return Note;

  })(Common);

  for (interval = j = 0, len = intervalMap.length; j < len; interval = ++j) {
    names = intervalMap[interval];
    for (k = 0, len1 = names.length; k < len1; k++) {
      name = names[k];
      Note.prototype[name] = function() {
        return this.transpose(interval);
      };
    }
  }

  for (i = l = 0; l < 9; i = ++l) {
    for (m = 0, len2 = chromaticNotes.length; m < len2; m++) {
      n = chromaticNotes[m];
      Note.retrieve(n, i);
    }
  }

  module.exports = Note;

}).call(this);

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