1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/media/libopus/silk/float/levinsondurbin_FLP.c Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,81 @@
1.4 +/***********************************************************************
1.5 +Copyright (c) 2006-2011, Skype Limited. All rights reserved.
1.6 +Redistribution and use in source and binary forms, with or without
1.7 +modification, are permitted provided that the following conditions
1.8 +are met:
1.9 +- Redistributions of source code must retain the above copyright notice,
1.10 +this list of conditions and the following disclaimer.
1.11 +- Redistributions in binary form must reproduce the above copyright
1.12 +notice, this list of conditions and the following disclaimer in the
1.13 +documentation and/or other materials provided with the distribution.
1.14 +- Neither the name of Internet Society, IETF or IETF Trust, nor the
1.15 +names of specific contributors, may be used to endorse or promote
1.16 +products derived from this software without specific prior written
1.17 +permission.
1.18 +THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
1.19 +AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
1.20 +IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
1.21 +ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
1.22 +LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
1.23 +CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
1.24 +SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
1.25 +INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
1.26 +CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
1.27 +ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
1.28 +POSSIBILITY OF SUCH DAMAGE.
1.29 +***********************************************************************/
1.30 +
1.31 +#ifdef HAVE_CONFIG_H
1.32 +#include "config.h"
1.33 +#endif
1.34 +
1.35 +#include "SigProc_FLP.h"
1.36 +
1.37 +/* Solve the normal equations using the Levinson-Durbin recursion */
1.38 +silk_float silk_levinsondurbin_FLP( /* O prediction error energy */
1.39 + silk_float A[], /* O prediction coefficients [order] */
1.40 + const silk_float corr[], /* I input auto-correlations [order + 1] */
1.41 + const opus_int order /* I prediction order */
1.42 +)
1.43 +{
1.44 + opus_int i, mHalf, m;
1.45 + silk_float min_nrg, nrg, t, km, Atmp1, Atmp2;
1.46 +
1.47 + min_nrg = 1e-12f * corr[ 0 ] + 1e-9f;
1.48 + nrg = corr[ 0 ];
1.49 + nrg = silk_max_float(min_nrg, nrg);
1.50 + A[ 0 ] = corr[ 1 ] / nrg;
1.51 + nrg -= A[ 0 ] * corr[ 1 ];
1.52 + nrg = silk_max_float(min_nrg, nrg);
1.53 +
1.54 + for( m = 1; m < order; m++ )
1.55 + {
1.56 + t = corr[ m + 1 ];
1.57 + for( i = 0; i < m; i++ ) {
1.58 + t -= A[ i ] * corr[ m - i ];
1.59 + }
1.60 +
1.61 + /* reflection coefficient */
1.62 + km = t / nrg;
1.63 +
1.64 + /* residual energy */
1.65 + nrg -= km * t;
1.66 + nrg = silk_max_float(min_nrg, nrg);
1.67 +
1.68 + mHalf = m >> 1;
1.69 + for( i = 0; i < mHalf; i++ ) {
1.70 + Atmp1 = A[ i ];
1.71 + Atmp2 = A[ m - i - 1 ];
1.72 + A[ m - i - 1 ] -= km * Atmp1;
1.73 + A[ i ] -= km * Atmp2;
1.74 + }
1.75 + if( m & 1 ) {
1.76 + A[ mHalf ] -= km * A[ mHalf ];
1.77 + }
1.78 + A[ m ] = km;
1.79 + }
1.80 +
1.81 + /* return the residual energy */
1.82 + return nrg;
1.83 +}
1.84 +
