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+/******************************** MPEG Audio Encoder **************************
+
+                     (C) Copyright Fraunhofer IIS (1997)
+                               All Rights Reserved
+
+    Please be advised that this software and/or program delivery is
+    Confidential Information of Fraunhofer and subject to and covered by the
+
+    Fraunhofer IIS Software Evaluation Agreement
+    between Google Inc. and  Fraunhofer
+    effective and in full force since March 1, 2012.
+
+    You may use this software and/or program only under the terms and
+    conditions described in the above mentioned Fraunhofer IIS Software
+    Evaluation Agreement. Any other and/or further use requires a separate agreement.
+
+
+   This software and/or program is protected by copyright law and international
+   treaties. Any reproduction or distribution of this software and/or program,
+   or any portion of it, may result in severe civil and criminal penalties, and
+   will be prosecuted to the maximum extent possible under law.
+
+   $Id$
+   Initial author:       M. Werner
+   contents/description: Chaos measure calculation
+
+******************************************************************************/
+
+#include "chaosmeasure.h"
+
+/*****************************************************************************
+    functionname: FDKaacEnc_FDKaacEnc_CalculateChaosMeasurePeakFast
+    description:  Eberlein method of chaos measure calculation by high-pass
+                  filtering amplitude spectrum
+                  A special case of FDKaacEnc_CalculateChaosMeasureTonalGeneric --
+                  highly optimized
+*****************************************************************************/
+static void
+FDKaacEnc_FDKaacEnc_CalculateChaosMeasurePeakFast( FIXP_DBL  *RESTRICT paMDCTDataNM0,
+                               INT        numberOfLines,
+                               FIXP_DBL  *RESTRICT chaosMeasure )
+{
+  INT i, j;
+
+  /* calculate chaos measure by "peak filter" */
+  for (i=0; i<2; i++) {
+    /* make even and odd pass through data */
+    FIXP_DBL left,center; /* left, center tap of filter */
+
+    left   = (FIXP_DBL)((LONG)paMDCTDataNM0[i]^((LONG)paMDCTDataNM0[i]>>(DFRACT_BITS-1)));
+    center = (FIXP_DBL)((LONG)paMDCTDataNM0[i+2]^((LONG)paMDCTDataNM0[i+2]>>(DFRACT_BITS-1)));
+
+    for (j = i+2; j < numberOfLines - 2; j+=2) {
+      FIXP_DBL right = (FIXP_DBL)((LONG)paMDCTDataNM0[j+2]^((LONG)paMDCTDataNM0[j+2]>>(DFRACT_BITS-1)));
+      FIXP_DBL tmp = (left>>1)+(right>>1);
+
+      if (tmp < center ) {
+         INT leadingBits = CntLeadingZeros(center)-1;
+         tmp = schur_div(tmp<<leadingBits, center<<leadingBits, 8);
+         chaosMeasure[j] = fMult(tmp,tmp);
+      }
+      else {
+         chaosMeasure[j] = (FIXP_DBL)MAXVAL_DBL;
+      }
+
+      left   = center;
+      center = right;
+    }
+  }
+
+  /* provide chaos measure for first few lines */
+  chaosMeasure[0] = chaosMeasure[2];
+  chaosMeasure[1] = chaosMeasure[2];
+
+  /* provide chaos measure for last few lines */
+  for (i = (numberOfLines-3); i < numberOfLines; i++)
+    chaosMeasure[i] = FL2FXCONST_DBL(0.5);
+}
+
+
+/*****************************************************************************
+    functionname: FDKaacEnc_CalculateChaosMeasure
+    description:  calculates a chaosmeasure for every line, different methods
+                  are available. 0 means tonal, 1 means noiselike
+    returns:
+    input:        MDCT data, number of lines
+    output:       chaosMeasure
+*****************************************************************************/
+void
+FDKaacEnc_CalculateChaosMeasure( FIXP_DBL    *paMDCTDataNM0,
+                       INT          numberOfLines,
+                       FIXP_DBL    *chaosMeasure )
+
+{
+    FDKaacEnc_FDKaacEnc_CalculateChaosMeasurePeakFast( paMDCTDataNM0,
+                                   numberOfLines,
+                                   chaosMeasure );
+}
+