Alexandre Lision | 744f742 | 2013-09-25 11:39:37 -0400 | [diff] [blame] | 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 | 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 | silk_float C[ SILK_MAX_ORDER_LPC + 1 ][ 2 ]; |
| 42 | silk_float Ctmp1, Ctmp2, rc_tmp; |
| 43 | |
| 44 | silk_assert( order==6||order==8||order==10||order==12||order==14||order==16 ); |
| 45 | |
| 46 | /* Copy correlations */ |
| 47 | for( k = 0; k < order+1; k++ ) { |
| 48 | C[ k ][ 0 ] = C[ k ][ 1 ] = auto_corr[ k ]; |
| 49 | } |
| 50 | |
| 51 | for( k = 0; k < order; k++ ) { |
| 52 | /* Get reflection coefficient */ |
| 53 | rc_tmp = -C[ k + 1 ][ 0 ] / silk_max_float( C[ 0 ][ 1 ], 1e-9f ); |
| 54 | |
| 55 | /* Save the output */ |
| 56 | refl_coef[ k ] = rc_tmp; |
| 57 | |
| 58 | /* Update correlations */ |
| 59 | for( n = 0; n < order - k; n++ ) { |
| 60 | Ctmp1 = C[ n + k + 1 ][ 0 ]; |
| 61 | Ctmp2 = C[ n ][ 1 ]; |
| 62 | C[ n + k + 1 ][ 0 ] = Ctmp1 + Ctmp2 * rc_tmp; |
| 63 | C[ n ][ 1 ] = Ctmp2 + Ctmp1 * rc_tmp; |
| 64 | } |
| 65 | } |
| 66 | |
| 67 | /* Return residual energy */ |
| 68 | return C[ 0 ][ 1 ]; |
| 69 | } |
| 70 | |