refactor: Move chunkware to third_party

third_party/chunkware_dsp/SimpleGateProcess.inl

@@ -0,0 +1,106 @@
+/*
+ *	Simple Gate (runtime function)
+ *
+ *  File		: SimpleGateProcess.inl
+ *	Library		: SimpleSource
+ *  Version		: 1.12
+ *  Implements	: void SimpleGate::process( double &in1, double &in2 )
+ *				  void SimpleGate::process( double &in1, double &in2, double keyLinked )
+ *				  void SimpleGateRms::process( double &in1, double &in2 )
+ *
+ *	2006, ChunkWare Music Software, OPEN-SOURCE
+ *
+ *	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 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 __SIMPLE_GATE_PROCESS_INL__
+#define __SIMPLE_GATE_PROCESS_INL__
+
+namespace chunkware_simple
+{
+	//-------------------------------------------------------------
+	INLINE void SimpleGate::process( double &in1, double &in2 )
+	{
+		// create sidechain
+
+		double rect1 = fabs( in1 );	// rectify input
+		double rect2 = fabs( in2 );
+
+		/* if desired, one could use another EnvelopeDetector to smooth
+		 * the rectified signal.
+		 */
+
+		double link = std::max( rect1, rect2 );	// link channels with greater of 2
+
+		process( in1, in2, link );	// rest of process
+	}
+
+	//-------------------------------------------------------------
+	INLINE void SimpleGate::process( double &in1, double &in2, double keyLinked )
+	{
+		keyLinked = fabs( keyLinked );	// rectify (just in case)
+
+		// threshold
+		// key over threshold ( 0.0 or 1.0 )
+		double over = double( keyLinked > thresh_ );
+
+		// attack/release
+		over += DC_OFFSET;					// add DC offset to avoid denormal
+		AttRelEnvelope::run( over, env_ );	// run attack/release
+		over = env_ - DC_OFFSET;			// subtract DC offset
+
+		/* REGARDING THE DC OFFSET: In this case, since the offset is added before 
+		 * the attack/release processes, the envelope will never fall below the offset,
+		 * thereby avoiding denormals. However, to prevent the offset from causing
+		 * constant gain reduction, we must subtract it from the envelope, yielding
+		 * a minimum value of 0dB.
+		 */
+
+		// output gain
+		in1 *= over;	// apply gain reduction to input
+		in2 *= over;
+	}
+
+	//-------------------------------------------------------------
+	INLINE void SimpleGateRms::process( double &in1, double &in2 )
+	{
+		// create sidechain
+
+		double inSq1 = in1 * in1;	// square input
+		double inSq2 = in2 * in2;
+
+		double sum = inSq1 + inSq2;			// power summing
+		sum += DC_OFFSET;					// DC offset, to prevent denormal
+		ave_.run( sum, aveOfSqrs_ );		// average of squares
+		double rms = sqrt( aveOfSqrs_ );	// rms (sort of ...)
+
+		/* REGARDING THE RMS AVERAGER: Ok, so this isn't a REAL RMS
+		 * calculation. A true RMS is an FIR moving average. This
+		 * approximation is a 1-pole IIR. Nonetheless, in practice,
+		 * and in the interest of simplicity, this method will suffice,
+		 * giving comparable results.
+		 */
+
+		SimpleGate::process( in1, in2, rms );	// rest of process
+	}
+
+}	// end namespace chunkware_simple
+
+#endif	// end __SIMPLE_GATE_PROCESS_INL__