Line data    Source code

       1             : /***********************************************************************
       2             : Copyright (c) 2006-2011, Skype Limited. All rights reserved.
       3             : Redistribution and use in source and binary forms, with or without
       4             : modification, are permitted provided that the following conditions
       5             : are met:
       6             : - Redistributions of source code must retain the above copyright notice,
       7             : this list of conditions and the following disclaimer.
       8             : - Redistributions in binary form must reproduce the above copyright
       9             : notice, this list of conditions and the following disclaimer in the
      10             : documentation and/or other materials provided with the distribution.
      11             : - Neither the name of Internet Society, IETF or IETF Trust, nor the
      12             : names of specific contributors, may be used to endorse or promote
      13             : products derived from this software without specific prior written
      14             : permission.
      15             : THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
      16             : AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
      17             : IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
      18             : ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
      19             : LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
      20             : CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
      21             : SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
      22             : INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
      23             : CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
      24             : ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
      25             : POSSIBILITY OF SUCH DAMAGE.
      26             : ***********************************************************************/
      27             : 
      28             : #ifdef HAVE_CONFIG_H
      29             : #include "config.h"
      30             : #endif
      31             : 
      32             : #include "SigProc_FLP.h"
      33             : 
      34           0 : silk_float silk_schur_FLP(                  /* O    returns residual energy                                     */
      35             :     silk_float          refl_coef[],        /* O    reflection coefficients (length order)                      */
      36             :     const silk_float    auto_corr[],        /* I    autocorrelation sequence (length order+1)                   */
      37             :     opus_int            order               /* I    order                                                       */
      38             : )
      39             : {
      40             :     opus_int   k, n;
      41             :     double C[ SILK_MAX_ORDER_LPC + 1 ][ 2 ];
      42             :     double Ctmp1, Ctmp2, rc_tmp;
      43             : 
      44           0 :     silk_assert( order >= 0 && order <= SILK_MAX_ORDER_LPC );
      45             : 
      46             :     /* Copy correlations */
      47           0 :     k = 0;
      48             :     do {
      49           0 :         C[ k ][ 0 ] = C[ k ][ 1 ] = auto_corr[ k ];
      50           0 :     } while( ++k <= order );
      51             : 
      52           0 :     for( k = 0; k < order; k++ ) {
      53             :         /* Get reflection coefficient */
      54           0 :         rc_tmp = -C[ k + 1 ][ 0 ] / silk_max_float( C[ 0 ][ 1 ], 1e-9f );
      55             : 
      56             :         /* Save the output */
      57           0 :         refl_coef[ k ] = (silk_float)rc_tmp;
      58             : 
      59             :         /* Update correlations */
      60           0 :         for( n = 0; n < order - k; n++ ) {
      61           0 :             Ctmp1 = C[ n + k + 1 ][ 0 ];
      62           0 :             Ctmp2 = C[ n ][ 1 ];
      63           0 :             C[ n + k + 1 ][ 0 ] = Ctmp1 + Ctmp2 * rc_tmp;
      64           0 :             C[ n ][ 1 ]         = Ctmp2 + Ctmp1 * rc_tmp;
      65             :         }
      66             :     }
      67             : 
      68             :     /* Return residual energy */
      69           0 :     return (silk_float)C[ 0 ][ 1 ];
      70             : }