Add AudioSynthNoiseWhite

Audio.h

 #include "synth_sine.h"
 #include "synth_waveform.h"
 #include "synth_dc.h"
+#include "synth_whitenoise.h"
 #include "multiplier.h"
 
 // TODO: more audio processing objects....

gui/list.html

 </script>
 
 
+<script type="text/javascript">
+	RED.nodes.registerType('AudioSynthNoiseWhite',{
+	shortName: "noise",
+		inputs:0,
+		outputs:1,
+		category: 'synth-function',
+		color:"#E6E0F8",
+		icon: "arrow-in.png"
+	});
+</script>
+<script type="text/x-red" data-help-name="AudioSynthNoiseWhite">
+	<h3>Summary</h3>
+	<div>
+	<p>Create white noise.
+		</p>
+	<p align=center><img src="whitenoise.png"></p>
+	</div>
+	<h3>Audio Connections</h3>
+	<table class=doc align=center cellpadding=3>
+		<tr class=top><th>Port</th><th>Purpose</th></tr>
+		<tr class=odd><td align=center>Out 0</td><td>White Noise</td></tr>
+	</table>
+	<h3>Functions</h3>
+	<p class=func><span class=keyword>amplitude</span>(level);</p>
+	<p class=desc>Set the output peak level, from 0 (off) to 1.0.
+		The default is off.  Noise is generated only after setting
+		to a non-zero level.
+	</p>
+	<h3>Notes</h3>
+	<p>Setting the amplitude to zero causes this object to stop using
+		CPU time to generate random numbers.
+	</p>
+</script>
+<script type="text/x-red" data-template-name="AudioSynthNoiseWhite">
+	<div class="form-row">
+		<label for="node-input-name"><i class="fa fa-tag"></i> Name</label>
+		<input type="text" id="node-input-name" placeholder="Name">
+	</div>
+</script>
+
+
+
+
 
 <script type="text/javascript">
 	RED.nodes.registerType('AudioEffectFade',{

keywords.txt

 AudioSynthWaveformSine	KEYWORD2
 AudioSynthWaveformSineModulated	KEYWORD2
 AudioSynthWaveformDc	KEYWORD2
+AudioSynthNoiseWhite	KEYWORD2
 isPlaying	KEYWORD2
 positionMillis	KEYWORD2
 lengthMillis	KEYWORD2

synth_whitenoise.cpp

+/* Audio Library for Teensy 3.X
+ * Copyright (c) 2014, Paul Stoffregen, paul@pjrc.com
+ *
+ * Development of this audio library was funded by PJRC.COM, LLC by sales of
+ * Teensy and Audio Adaptor boards.  Please support PJRC's efforts to develop
+ * open source software by purchasing Teensy or other PJRC products.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice, development funding notice, and this permission
+ * notice shall be included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "synth_whitenoise.h"
+
+// Park-Miller-Carta Pseudo-Random Number Generator
+// http://www.firstpr.com.au/dsp/rand31/
+
+void AudioSynthNoiseWhite::update(void)
+{
+	audio_block_t *block;
+	uint32_t *p, *end;
+	int32_t n1, n2, gain;
+	uint32_t lo, hi, val1, val2;
+
+	gain = level;
+	if (gain == 0) return;
+	block = allocate();
+	if (!block) return;
+	p = (uint32_t *)(block->data);
+	end = p + AUDIO_BLOCK_SAMPLES/2;
+	lo = seed;
+	do {
+		hi = multiply_16bx16t(16807, lo); // 16807 * (lo >> 16)
+		lo = 16807 * (lo & 0xFFFF);
+		lo += (hi & 0x7FFF) << 16;
+		lo += hi >> 15;
+		lo = (lo & 0x7FFFFFFF) + (lo >> 31);
+		n1 = signed_multiply_32x16b(gain, lo);
+		hi = multiply_16bx16t(16807, lo); // 16807 * (lo >> 16)
+		lo = 16807 * (lo & 0xFFFF);
+		lo += (hi & 0x7FFF) << 16;
+		lo += hi >> 15;
+		lo = (lo & 0x7FFFFFFF) + (lo >> 31);
+		n2 = signed_multiply_32x16b(gain, lo);
+		val1 = pack_16b_16b(n2, n1);
+		hi = multiply_16bx16t(16807, lo); // 16807 * (lo >> 16)
+		lo = 16807 * (lo & 0xFFFF);
+		lo += (hi & 0x7FFF) << 16;
+		lo += hi >> 15;
+		lo = (lo & 0x7FFFFFFF) + (lo >> 31);
+		n1 = signed_multiply_32x16b(gain, lo);
+		hi = multiply_16bx16t(16807, lo); // 16807 * (lo >> 16)
+		lo = 16807 * (lo & 0xFFFF);
+		lo += (hi & 0x7FFF) << 16;
+		lo += hi >> 15;
+		lo = (lo & 0x7FFFFFFF) + (lo >> 31);
+		n2 = signed_multiply_32x16b(gain, lo);
+		val2 = pack_16b_16b(n2, n1);
+		*p++ = val1;
+		*p++ = val2;
+	} while (p < end);
+	seed = lo;
+	transmit(block);
+	release(block);
+}
+
+
+

synth_whitenoise.h

+/* Audio Library for Teensy 3.X
+ * Copyright (c) 2014, Paul Stoffregen, paul@pjrc.com
+ *
+ * Development of this audio library was funded by PJRC.COM, LLC by sales of
+ * Teensy and Audio Adaptor boards.  Please support PJRC's efforts to develop
+ * open source software by purchasing Teensy or other PJRC products.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice, development funding notice, and this permission
+ * notice shall be included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#ifndef synth_whitenoise_h_
+#define synth_whitenoise_h_
+#include "AudioStream.h"
+#include "utility/dspinst.h"
+
+class AudioSynthNoiseWhite : public AudioStream
+{
+public:
+	AudioSynthNoiseWhite() : AudioStream(0, NULL), level(0), seed(1) {}
+	void amplitude(float n) {
+		if (n < 0.0) n = 0.0;
+		else if (n > 1.0) n = 1.0;
+		level = (int32_t)(n * 65536.0);
+	}
+	virtual void update(void);
+private:
+	int32_t  level; // 0=off, 65536=max
+	uint32_t seed;  // must start at 1
+};
+
+#endif