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Diffstat (limited to 'silk/float/schur_FLP.c')
| -rw-r--r-- | silk/float/schur_FLP.c | 70 |
1 files changed, 70 insertions, 0 deletions
diff --git a/silk/float/schur_FLP.c b/silk/float/schur_FLP.c new file mode 100644 index 0000000..90c3a18 --- /dev/null +++ b/silk/float/schur_FLP.c @@ -0,0 +1,70 @@ +/*********************************************************************** +Copyright (c) 2006-2011, Skype Limited. All rights reserved. +Redistribution and use in source and binary forms, with or without +modification, are permitted provided that the following conditions +are met: +- Redistributions of source code must retain the above copyright notice, +this list of conditions and the following disclaimer. +- 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. +- Neither the name of Internet Society, IETF or IETF Trust, nor the +names of specific contributors, may be used to endorse or promote +products derived from this software without specific prior written +permission. +THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS “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 COPYRIGHT OWNER OR CONTRIBUTORS 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. +***********************************************************************/ + +#ifdef HAVE_CONFIG_H +#include "config.h" +#endif + +#include "SigProc_FLP.h" + +silk_float silk_schur_FLP( /* O returns residual energy */ + silk_float refl_coef[], /* O reflection coefficients (length order) */ + const silk_float auto_corr[], /* I autocorrelation sequence (length order+1) */ + opus_int order /* I order */ +) +{ + opus_int k, n; + silk_float C[ SILK_MAX_ORDER_LPC + 1 ][ 2 ]; + silk_float Ctmp1, Ctmp2, rc_tmp; + + silk_assert( order==6||order==8||order==10||order==12||order==14||order==16 ); + + /* Copy correlations */ + for( k = 0; k < order+1; k++ ) { + C[ k ][ 0 ] = C[ k ][ 1 ] = auto_corr[ k ]; + } + + for( k = 0; k < order; k++ ) { + /* Get reflection coefficient */ + rc_tmp = -C[ k + 1 ][ 0 ] / silk_max_float( C[ 0 ][ 1 ], 1e-9f ); + + /* Save the output */ + refl_coef[ k ] = rc_tmp; + + /* Update correlations */ + for( n = 0; n < order - k; n++ ) { + Ctmp1 = C[ n + k + 1 ][ 0 ]; + Ctmp2 = C[ n ][ 1 ]; + C[ n + k + 1 ][ 0 ] = Ctmp1 + Ctmp2 * rc_tmp; + C[ n ][ 1 ] = Ctmp2 + Ctmp1 * rc_tmp; + } + } + + /* Return residual energy */ + return C[ 0 ][ 1 ]; +} + |