Add working test for DTMF.

README.md

@@ -140,6 +140,11 @@ Goertzel.Utilities.doublePeakFilter(energies1,energies2,sensitivity)
 
 doublePeakFilter does the same thing as the normal peak filter but with two arrays at the same time.  
 
+```javascript
+Goertzel.Utilities.generateSineBuffer(frequencies=[], sampleRate, numberOfSamples)
+```
+generateSineBuffer lets you create an artificial buffer of any number of combined sine waves.  Added for testing purposes, but could have any number of uses.  If you needed to create an oscillator to generate DTMF or other tones without access to a browser's audio API, that's your function.
+
 
 ## conclusion
 I hope this project will be useful for anyone who wants to understand the Goertzel algorithm or basic signal processing with the HTML5 Audio API.  

spec/dtmf.spec.coffee

@@ -0,0 +1,36 @@
+`Goertzel = require('../build/goertzel');`
+DTMF     = require('../build/dtmf')
+require('jasmine-expect')
+
+describe 'DTMF', ->
+
+  pairs = [
+    {low: 697, high: 1209, char: '1'}
+    {low: 697, high: 1336, char: '2'}
+    {low: 697, high: 1477, char: '3'}
+    {low: 697, high: 1633, char: 'A'}
+    {low: 770, high: 1209, char: '4'}
+    {low: 770, high: 1336, char: '5'}
+    {low: 770, high: 1477, char: '6'}
+    {low: 770, high: 1633, char: 'B'}
+    {low: 852, high: 1209, char: '7'}
+    {low: 852, high: 1336, char: '8'}
+    {low: 852, high: 1477, char: '9'}
+    {low: 852, high: 1633, char: 'C'}
+    {low: 941, high: 1209, char: '*'}
+    {low: 941, high: 1336, char: '0'}
+    {low: 941, high: 1477, char: '#'}
+    {low: 941, high: 1633, char: 'D'}
+  ]
+
+  describe '#processSample', ->
+    it 'identifies all dial tones', ->
+      dtmf = new DTMF
+        sampleRate: 44100
+        peakFilterSensitivity: 1.4
+        repeatMin: 1
+      for pair in pairs
+        dualTone = Goertzel.Utilities.generateSineBuffer([pair.low, pair.high], 44100, 512)
+        buffer = Goertzel.Utilities.floatBufferToInt(dualTone)
+        dtmf.processBuffer(buffer)
+        expect(dtmf.processBuffer(buffer)).toContain(pair.char)

spec/goertzel.spec.coffee

@@ -18,7 +18,7 @@ describe 'Goertzel', ->
 
     it 'biases towards the expected frequency', ->
       for frequency in allFrequencies
-        buffer = Goertzel.Utilities.generateSine(frequency, 8000, 2000)
+        buffer = Goertzel.Utilities.generateSineBuffer([frequency], 8000, 2000)
         for sample in buffer
           goertzel.processSample sample
         for f in allFrequencies

src/goertzel.coffee

@@ -104,20 +104,25 @@ class Goertzel
         false
 
     ## useful for testing purposes
-    generateSine: (frequency, sampleRate, numberOfSamples) ->
-      buffer = []
+
+    generateSineBuffer: (frequencies, sampleRate, numberOfSamples) ->
+      buffer = new (Uint8ClampedArray or Array)(numberOfSamples)
+      volumePerSine = 1 / frequencies.length
       i = 0
       while i < numberOfSamples
-        v = Math.sin(Math.PI * 2 * (i / sampleRate) * frequency)
-        buffer.push v
+        val = 0
+        for frequency in frequencies
+          val += (Math.sin(Math.PI * 2 * (i / sampleRate) * frequency) * volumePerSine)
+        buffer[i] = val
         i++
-      buffer
+      buffer      
 
     floatBufferToInt: (floatBuffer) ->
-      intBuffer = []
+      floatBufferLength = floatBuffer.length
+      intBuffer = new (Uint8ClampedArray or Array)(floatBufferLength)
       i = 0
-      while i < floatBuffer.length
-        intBuffer.push Goertzel.Utilities.floatToIntSample(floatBuffer[i])
+      while i < floatBufferLength
+        intBuffer[i] = Goertzel.Utilities.floatToIntSample(floatBuffer[i])
         i++
       intBuffer