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+/*
+Copyright (c) 2015, John Hurst
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions
+are met:
+1. Redistributions of source code must retain the above copyright
+   notice, this list of conditions and the following disclaimer.
+2. Redistributions in binary form must reproduce the above copyright
+   notice, this list of conditions and the following disclaimer in the
+   documentation and/or other materials provided with the distribution.
+3. The name of the author may not be used to endorse or promote products
+   derived from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+/*! \file    ST2095_PinkNoise.h
+    \version $Id$
+    \brief   Pink Noise filter and LCG generator
+*/
+
+
+#ifndef _ST2095_PINKNOISE_H_
+#define _ST2095_PINKNOISE_H_
+
+#include <KM_fileio.h>
+#include <cmath>
+
+//
+// No attempt will be made here to explain the theory of operation of
+// this noise source since all of the gory detail can be found in SMPTE
+// ST 2095-1:2015.  Get your copy from SMPTE today!
+//
+
+
+namespace ASDCP
+{
+  // A source of pseudo-random numbers suitable for use in generating
+  // noise signals.  NOT TO BE USED FOR CRYPTOGRAPHIC FUNCTIONS as its
+  // output is 100% deterministic.
+  class LinearCongruentialGenerator
+  {
+    ui32_t m_Seed, m_RandMax;
+    float m_ScaleFactor;
+
+    KM_NO_COPY_CONSTRUCT(LinearCongruentialGenerator);
+
+  public:
+
+    LinearCongruentialGenerator(const ui32_t sample_rate);
+    float GetNextSample();
+  };
+
+  //
+  float const PinkFilterHighPassConstant = 10.0; // Hz
+  float const PinkFilterLowPassConstant = 22400.0; // Hz
+
+  //
+  class PinkFilter
+  {
+    // storage for biquad coefficients for bandpass filter components
+    float hp1_a1, hp1_a2;
+    float hp1_b0, hp1_b1, hp1_b2;
+    float hp2_a1, hp2_a2;
+    float hp2_b0, hp2_b1, hp2_b2;
+    float lp1_a1, lp1_a2;
+    float lp1_b0, lp1_b1, lp1_b2;
+    float lp2_a1, lp2_a2;
+    float lp2_b0, lp2_b1, lp2_b2;
+
+    // storage for delay line variables for bandpass filter and initialize to zero
+    float hp1w1, hp1w2, hp2w1, hp2w2;
+    float lp1w1, lp1w2, lp2w1, lp2w2;
+
+    // storage for delay lines for pink filter network and initialize to zero
+    float lp1, lp2, lp3, lp4, lp5, lp6;
+
+    KM_NO_COPY_CONSTRUCT(PinkFilter);
+
+  public:
+
+    PinkFilter(const i32_t SampleRate, const float HpFc, const float LpFc);
+    
+    // Using a white noise sample as input, produce a pink noise sample
+    // having properties as defined by SMPTE ST 2095-1:2015.
+    float GetNextSample(const float white);
+  };
+
+  // Create a little-endian integer audio sample of the sepcified word size
+  // (1-4 bytes) from the normalized input value, write it to the buffer at p.
+  void ScalePackSample(float sample, byte_t* p, ui32_t word_size);
+
+
+} // namespace ASDCP
+
+
+
+#endif // _ST2095_PINKNOISE_H_
+
+
+//
+// end ST2095_PinkNoise.h
+//